1 /*
2 * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "classfile/vmSymbols.hpp"
28 #include "gc/shared/gcLocker.hpp"
29 #include "logging/log.hpp"
30 #include "logging/logStream.hpp"
31 #include "memory/metaspaceShared.hpp"
32 #include "memory/resourceArea.hpp"
33 #include "memory/universe.inline.hpp"
34 #include "oops/instanceKlass.hpp"
35 #include "oops/klassVtable.hpp"
36 #include "oops/method.hpp"
37 #include "oops/objArrayOop.hpp"
38 #include "oops/oop.inline.hpp"
39 #include "prims/jvm.h"
40 #include "runtime/arguments.hpp"
41 #include "runtime/handles.inline.hpp"
42 #include "utilities/copy.hpp"
43
44 inline InstanceKlass* klassVtable::ik() const {
45 return InstanceKlass::cast(_klass);
46 }
47
48 bool klassVtable::is_preinitialized_vtable() {
49 return _klass->is_shared() && !MetaspaceShared::remapped_readwrite();
50 }
51
52
53 // this function computes the vtable size (including the size needed for miranda
54 // methods) and the number of miranda methods in this class.
55 // Note on Miranda methods: Let's say there is a class C that implements
56 // interface I, and none of C's superclasses implements I.
57 // Let's say there is an abstract method m in I that neither C
58 // nor any of its super classes implement (i.e there is no method of any access,
59 // with the same name and signature as m), then m is a Miranda method which is
60 // entered as a public abstract method in C's vtable. From then on it should
61 // treated as any other public method in C for method over-ride purposes.
62 void klassVtable::compute_vtable_size_and_num_mirandas(
63 int* vtable_length_ret, int* num_new_mirandas,
64 GrowableArray<Method*>* all_mirandas, const Klass* super,
65 Array<Method*>* methods, AccessFlags class_flags, u2 major_version,
66 Handle classloader, Symbol* classname, Array<Klass*>* local_interfaces,
67 TRAPS) {
68 NoSafepointVerifier nsv;
69
70 // set up default result values
71 int vtable_length = 0;
72
73 // start off with super's vtable length
74 vtable_length = super == NULL ? 0 : super->vtable_length();
75
76 // go thru each method in the methods table to see if it needs a new entry
77 int len = methods->length();
78 for (int i = 0; i < len; i++) {
79 assert(methods->at(i)->is_method(), "must be a Method*");
80 methodHandle mh(THREAD, methods->at(i));
81
82 if (needs_new_vtable_entry(mh, super, classloader, classname, class_flags, major_version, THREAD)) {
83 vtable_length += vtableEntry::size(); // we need a new entry
84 }
85 }
86
87 GrowableArray<Method*> new_mirandas(20);
88 // compute the number of mirandas methods that must be added to the end
89 get_mirandas(&new_mirandas, all_mirandas, super, methods, NULL, local_interfaces);
90 *num_new_mirandas = new_mirandas.length();
91
92 // Interfaces do not need interface methods in their vtables
93 // This includes miranda methods and during later processing, default methods
94 if (!class_flags.is_interface()) {
95 vtable_length += *num_new_mirandas * vtableEntry::size();
96 }
97
98 if (Universe::is_bootstrapping() && vtable_length == 0) {
99 // array classes don't have their superclass set correctly during
100 // bootstrapping
101 vtable_length = Universe::base_vtable_size();
102 }
103
104 if (super == NULL && vtable_length != Universe::base_vtable_size()) {
105 if (Universe::is_bootstrapping()) {
106 // Someone is attempting to override java.lang.Object incorrectly on the
107 // bootclasspath. The JVM cannot recover from this error including throwing
108 // an exception
109 vm_exit_during_initialization("Incompatible definition of java.lang.Object");
110 } else {
111 // Someone is attempting to redefine java.lang.Object incorrectly. The
112 // only way this should happen is from
113 // SystemDictionary::resolve_from_stream(), which will detect this later
114 // and throw a security exception. So don't assert here to let
115 // the exception occur.
116 vtable_length = Universe::base_vtable_size();
117 }
118 }
119 assert(vtable_length % vtableEntry::size() == 0, "bad vtable length");
120 assert(vtable_length >= Universe::base_vtable_size(), "vtable too small");
121
122 *vtable_length_ret = vtable_length;
123 }
124
125 int klassVtable::index_of(Method* m, int len) const {
126 assert(m->has_vtable_index(), "do not ask this of non-vtable methods");
127 return m->vtable_index();
128 }
129
130 // Copy super class's vtable to the first part (prefix) of this class's vtable,
131 // and return the number of entries copied. Expects that 'super' is the Java
132 // super class (arrays can have "array" super classes that must be skipped).
133 int klassVtable::initialize_from_super(Klass* super) {
134 if (super == NULL) {
135 return 0;
136 } else if (is_preinitialized_vtable()) {
137 // A shared class' vtable is preinitialized at dump time. No need to copy
138 // methods from super class for shared class, as that was already done
139 // during archiving time. However, if Jvmti has redefined a class,
140 // copy super class's vtable in case the super class has changed.
141 return super->vtable().length();
142 } else {
143 // copy methods from superKlass
144 klassVtable superVtable = super->vtable();
145 assert(superVtable.length() <= _length, "vtable too short");
146 #ifdef ASSERT
147 superVtable.verify(tty, true);
148 #endif
149 superVtable.copy_vtable_to(table());
150 if (log_develop_is_enabled(Trace, vtables)) {
151 ResourceMark rm;
152 log_develop_trace(vtables)("copy vtable from %s to %s size %d",
153 super->internal_name(), klass()->internal_name(),
154 _length);
155 }
156 return superVtable.length();
157 }
158 }
159
160 //
161 // Revised lookup semantics introduced 1.3 (Kestrel beta)
162 void klassVtable::initialize_vtable(bool checkconstraints, TRAPS) {
163
164 // Note: Arrays can have intermediate array supers. Use java_super to skip them.
165 Klass* super = _klass->java_super();
166 int nofNewEntries = 0;
167
168 bool is_shared = _klass->is_shared();
169
170 if (!_klass->is_array_klass()) {
171 ResourceMark rm(THREAD);
172 log_develop_debug(vtables)("Initializing: %s", _klass->name()->as_C_string());
173 }
174
175 #ifdef ASSERT
176 oop* end_of_obj = (oop*)_klass + _klass->size();
177 oop* end_of_vtable = (oop*)&table()[_length];
178 assert(end_of_vtable <= end_of_obj, "vtable extends beyond end");
179 #endif
180
181 if (Universe::is_bootstrapping()) {
182 assert(!is_shared, "sanity");
183 // just clear everything
184 for (int i = 0; i < _length; i++) table()[i].clear();
185 return;
186 }
187
188 int super_vtable_len = initialize_from_super(super);
189 if (_klass->is_array_klass()) {
190 assert(super_vtable_len == _length, "arrays shouldn't introduce new methods");
191 } else {
192 assert(_klass->is_instance_klass(), "must be InstanceKlass");
193
194 Array<Method*>* methods = ik()->methods();
195 int len = methods->length();
196 int initialized = super_vtable_len;
197
198 // Check each of this class's methods against super;
199 // if override, replace in copy of super vtable, otherwise append to end
200 for (int i = 0; i < len; i++) {
201 // update_inherited_vtable can stop for gc - ensure using handles
202 HandleMark hm(THREAD);
203 assert(methods->at(i)->is_method(), "must be a Method*");
204 methodHandle mh(THREAD, methods->at(i));
205
206 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, -1, checkconstraints, CHECK);
207
208 if (needs_new_entry) {
209 put_method_at(mh(), initialized);
210 mh()->set_vtable_index(initialized); // set primary vtable index
211 initialized++;
212 }
213 }
214
215 // update vtable with default_methods
216 Array<Method*>* default_methods = ik()->default_methods();
217 if (default_methods != NULL) {
218 len = default_methods->length();
219 if (len > 0) {
220 Array<int>* def_vtable_indices = NULL;
221 if ((def_vtable_indices = ik()->default_vtable_indices()) == NULL) {
222 assert(!is_shared, "shared class def_vtable_indices does not exist");
223 def_vtable_indices = ik()->create_new_default_vtable_indices(len, CHECK);
224 } else {
225 assert(def_vtable_indices->length() == len, "reinit vtable len?");
226 }
227 for (int i = 0; i < len; i++) {
228 HandleMark hm(THREAD);
229 assert(default_methods->at(i)->is_method(), "must be a Method*");
230 methodHandle mh(THREAD, default_methods->at(i));
231 assert(!mh->is_private(), "private interface method in the default method list");
232 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, i, checkconstraints, CHECK);
233
234 // needs new entry
235 if (needs_new_entry) {
236 put_method_at(mh(), initialized);
237 if (is_preinitialized_vtable()) {
238 // At runtime initialize_vtable is rerun for a shared class
239 // (loaded by the non-boot loader) as part of link_class_impl().
240 // The dumptime vtable index should be the same as the runtime index.
241 assert(def_vtable_indices->at(i) == initialized,
242 "dump time vtable index is different from runtime index");
243 } else {
244 def_vtable_indices->at_put(i, initialized); //set vtable index
245 }
246 initialized++;
247 }
248 }
249 }
250 }
251
252 // add miranda methods; it will also return the updated initialized
253 // Interfaces do not need interface methods in their vtables
254 // This includes miranda methods and during later processing, default methods
255 if (!ik()->is_interface()) {
256 initialized = fill_in_mirandas(initialized);
257 }
258
259 // In class hierarchies where the accessibility is not increasing (i.e., going from private ->
260 // package_private -> public/protected), the vtable might actually be smaller than our initial
261 // calculation, for classfile versions for which we do not do transitive override
262 // calculations.
263 if (ik()->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) {
264 assert(initialized == _length, "vtable initialization failed");
265 } else {
266 assert(initialized <= _length, "vtable initialization failed");
267 for(;initialized < _length; initialized++) {
268 table()[initialized].clear();
269 }
270 }
271 NOT_PRODUCT(verify(tty, true));
272 }
273 }
274
275 // Called for cases where a method does not override its superclass' vtable entry
276 // For bytecodes not produced by javac together it is possible that a method does not override
277 // the superclass's method, but might indirectly override a super-super class's vtable entry
278 // If none found, return a null superk, else return the superk of the method this does override
279 // For public and protected methods: if they override a superclass, they will
280 // also be overridden themselves appropriately.
281 // Private methods do not override and are not overridden.
282 // Package Private methods are trickier:
283 // e.g. P1.A, pub m
284 // P2.B extends A, package private m
285 // P1.C extends B, public m
286 // P1.C.m needs to override P1.A.m and can not override P2.B.m
287 // Therefore: all package private methods need their own vtable entries for
288 // them to be the root of an inheritance overriding decision
289 // Package private methods may also override other vtable entries
290 InstanceKlass* klassVtable::find_transitive_override(InstanceKlass* initialsuper, const methodHandle& target_method,
291 int vtable_index, Handle target_loader, Symbol* target_classname, Thread * THREAD) {
292 InstanceKlass* superk = initialsuper;
293 while (superk != NULL && superk->super() != NULL) {
294 InstanceKlass* supersuperklass = InstanceKlass::cast(superk->super());
295 klassVtable ssVtable = supersuperklass->vtable();
296 if (vtable_index < ssVtable.length()) {
297 Method* super_method = ssVtable.method_at(vtable_index);
298 #ifndef PRODUCT
299 Symbol* name= target_method()->name();
300 Symbol* signature = target_method()->signature();
301 assert(super_method->name() == name && super_method->signature() == signature, "vtable entry name/sig mismatch");
302 #endif
303 if (supersuperklass->is_override(super_method, target_loader, target_classname, THREAD)) {
304 if (log_develop_is_enabled(Trace, vtables)) {
305 ResourceMark rm(THREAD);
306 LogTarget(Trace, vtables) lt;
307 LogStream ls(lt);
308 char* sig = target_method()->name_and_sig_as_C_string();
309 ls.print("transitive overriding superclass %s with %s index %d, original flags: ",
310 supersuperklass->internal_name(),
311 sig, vtable_index);
312 super_method->print_linkage_flags(&ls);
313 ls.print("overriders flags: ");
314 target_method->print_linkage_flags(&ls);
315 ls.cr();
316 }
317
318 break; // return found superk
319 }
320 } else {
321 // super class has no vtable entry here, stop transitive search
322 superk = (InstanceKlass*)NULL;
323 break;
324 }
325 // if no override found yet, continue to search up
326 superk = superk->super() == NULL ? NULL : InstanceKlass::cast(superk->super());
327 }
328
329 return superk;
330 }
331
332 static void log_vtables(int i, bool overrides, const methodHandle& target_method,
333 Klass* target_klass, Method* super_method,
334 Thread* thread) {
335 #ifndef PRODUCT
336 if (log_develop_is_enabled(Trace, vtables)) {
337 ResourceMark rm(thread);
338 LogTarget(Trace, vtables) lt;
339 LogStream ls(lt);
340 char* sig = target_method()->name_and_sig_as_C_string();
341 if (overrides) {
342 ls.print("overriding with %s index %d, original flags: ",
343 sig, i);
344 } else {
345 ls.print("NOT overriding with %s index %d, original flags: ",
346 sig, i);
347 }
348 super_method->print_linkage_flags(&ls);
349 ls.print("overriders flags: ");
350 target_method->print_linkage_flags(&ls);
351 ls.cr();
352 }
353 #endif
354 }
355
356 // Update child's copy of super vtable for overrides
357 // OR return true if a new vtable entry is required.
358 // Only called for InstanceKlass's, i.e. not for arrays
359 // If that changed, could not use _klass as handle for klass
360 bool klassVtable::update_inherited_vtable(InstanceKlass* klass, const methodHandle& target_method,
361 int super_vtable_len, int default_index,
362 bool checkconstraints, TRAPS) {
363 ResourceMark rm;
364 bool allocate_new = true;
365 assert(klass->is_instance_klass(), "must be InstanceKlass");
366
367 Array<int>* def_vtable_indices = NULL;
368 bool is_default = false;
369
370 // default methods are non-private concrete methods in superinterfaces which are added
371 // to the vtable with their real method_holder.
372 // Since vtable and itable indices share the same storage, don't touch
373 // the default method's real vtable/itable index.
374 // default_vtable_indices stores the vtable value relative to this inheritor
375 if (default_index >= 0 ) {
376 is_default = true;
377 def_vtable_indices = klass->default_vtable_indices();
378 assert(!target_method()->is_private(), "private interface method flagged as default");
379 assert(def_vtable_indices != NULL, "def vtable alloc?");
380 assert(default_index <= def_vtable_indices->length(), "def vtable len?");
381 } else {
382 assert(klass == target_method()->method_holder(), "caller resp.");
383 // Initialize the method's vtable index to "nonvirtual".
384 // If we allocate a vtable entry, we will update it to a non-negative number.
385 target_method()->set_vtable_index(Method::nonvirtual_vtable_index);
386 }
387
388 // Static and <init> methods are never in
389 if (target_method()->is_static() || target_method()->name() == vmSymbols::object_initializer_name()) {
390 return false;
391 }
392
393 if (target_method->is_final_method(klass->access_flags())) {
394 // a final method never needs a new entry; final methods can be statically
395 // resolved and they have to be present in the vtable only if they override
396 // a super's method, in which case they re-use its entry
397 allocate_new = false;
398 } else if (klass->is_interface()) {
399 allocate_new = false; // see note below in needs_new_vtable_entry
400 // An interface never allocates new vtable slots, only inherits old ones.
401 // This method will either be assigned its own itable index later,
402 // or be assigned an inherited vtable index in the loop below.
403 // default methods inherited by classes store their vtable indices
404 // in the inheritor's default_vtable_indices.
405 // default methods inherited by interfaces may already have a
406 // valid itable index, if so, don't change it.
407 // Overpass methods in an interface will be assigned an itable index later
408 // by an inheriting class.
409 // Private interface methods have no itable index and are always invoked nonvirtually,
410 // so they retain their nonvirtual_vtable_index value, and therefore can_be_statically_bound()
411 // will return true.
412 if ((!is_default || !target_method()->has_itable_index()) && !target_method()->is_private()) {
413 target_method()->set_vtable_index(Method::pending_itable_index);
414 }
415 }
416
417 // we need a new entry if there is no superclass
418 Klass* super = klass->super();
419 if (super == NULL) {
420 return allocate_new;
421 }
422
423 // private methods in classes always have a new entry in the vtable
424 // specification interpretation since classic has
425 // private methods not overriding
426 // JDK8 adds private methods in interfaces which require invokespecial
427 if (target_method()->is_private()) {
428 return allocate_new;
429 }
430
431 // search through the vtable and update overridden entries
432 // Since check_signature_loaders acquires SystemDictionary_lock
433 // which can block for gc, once we are in this loop, use handles
434 // For classfiles built with >= jdk7, we now look for transitive overrides
435
436 Symbol* name = target_method()->name();
437 Symbol* signature = target_method()->signature();
438
439 Klass* target_klass = target_method()->method_holder();
440 if (target_klass == NULL) {
441 target_klass = _klass;
442 }
443
444 Handle target_loader(THREAD, target_klass->class_loader());
445
446 Symbol* target_classname = target_klass->name();
447 for(int i = 0; i < super_vtable_len; i++) {
448 Method* super_method;
449 if (is_preinitialized_vtable()) {
450 // If this is a shared class, the vtable is already in the final state (fully
451 // initialized). Need to look at the super's vtable.
452 klassVtable superVtable = super->vtable();
453 super_method = superVtable.method_at(i);
454 } else {
455 super_method = method_at(i);
456 }
457 // Check if method name matches
458 if (super_method->name() == name && super_method->signature() == signature) {
459
460 // get super_klass for method_holder for the found method
461 InstanceKlass* super_klass = super_method->method_holder();
462
463 // Whether the method is being overridden
464 bool overrides = false;
465
466 // private methods are also never overridden
467 if (!super_method->is_private() &&
468 (is_default
469 || ((super_klass->is_override(super_method, target_loader, target_classname, THREAD))
470 || ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION)
471 && ((super_klass = find_transitive_override(super_klass,
472 target_method, i, target_loader,
473 target_classname, THREAD))
474 != (InstanceKlass*)NULL)))))
475 {
476 // Package private methods always need a new entry to root their own
477 // overriding. They may also override other methods.
478 if (!target_method()->is_package_private()) {
479 allocate_new = false;
480 }
481
482 if (checkconstraints) {
483 // Override vtable entry if passes loader constraint check
484 // if loader constraint checking requested
485 // No need to visit his super, since he and his super
486 // have already made any needed loader constraints.
487 // Since loader constraints are transitive, it is enough
488 // to link to the first super, and we get all the others.
489 Handle super_loader(THREAD, super_klass->class_loader());
490
491 if (target_loader() != super_loader()) {
492 ResourceMark rm(THREAD);
493 Symbol* failed_type_symbol =
494 SystemDictionary::check_signature_loaders(signature, target_loader,
495 super_loader, true,
496 CHECK_(false));
497 if (failed_type_symbol != NULL) {
498 const char* msg = "loader constraint violation: when resolving "
499 "overridden method \"%s\" the class loader (instance"
500 " of %s) of the current class, %s, and its superclass loader "
501 "(instance of %s), have different Class objects for the type "
502 "%s used in the signature";
503 char* sig = target_method()->name_and_sig_as_C_string();
504 const char* loader1 = SystemDictionary::loader_name(target_loader());
505 char* current = target_klass->name()->as_C_string();
506 const char* loader2 = SystemDictionary::loader_name(super_loader());
507 char* failed_type_name = failed_type_symbol->as_C_string();
508 size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) +
509 strlen(current) + strlen(loader2) + strlen(failed_type_name);
510 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
511 jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2,
512 failed_type_name);
513 THROW_MSG_(vmSymbols::java_lang_LinkageError(), buf, false);
514 }
515 }
516 }
517
518 put_method_at(target_method(), i);
519 overrides = true;
520 if (!is_default) {
521 target_method()->set_vtable_index(i);
522 } else {
523 if (def_vtable_indices != NULL) {
524 if (is_preinitialized_vtable()) {
525 // At runtime initialize_vtable is rerun as part of link_class_impl()
526 // for a shared class loaded by the non-boot loader.
527 // The dumptime vtable index should be the same as the runtime index.
528 assert(def_vtable_indices->at(default_index) == i,
529 "dump time vtable index is different from runtime index");
530 } else {
531 def_vtable_indices->at_put(default_index, i);
532 }
533 }
534 assert(super_method->is_default_method() || super_method->is_overpass()
535 || super_method->is_abstract(), "default override error");
536 }
537 } else {
538 overrides = false;
539 }
540 log_vtables(i, overrides, target_method, target_klass, super_method, THREAD);
541 }
542 }
543 return allocate_new;
544 }
545
546 void klassVtable::put_method_at(Method* m, int index) {
547 if (is_preinitialized_vtable()) {
548 // At runtime initialize_vtable is rerun as part of link_class_impl()
549 // for shared class loaded by the non-boot loader to obtain the loader
550 // constraints based on the runtime classloaders' context. The dumptime
551 // method at the vtable index should be the same as the runtime method.
552 assert(table()[index].method() == m,
553 "archived method is different from the runtime method");
554 } else {
555 if (log_develop_is_enabled(Trace, vtables)) {
556 ResourceMark rm;
557 LogTarget(Trace, vtables) lt;
558 LogStream ls(lt);
559 const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>";
560 ls.print("adding %s at index %d, flags: ", sig, index);
561 if (m != NULL) {
562 m->print_linkage_flags(&ls);
563 }
564 ls.cr();
565 }
566 table()[index].set(m);
567 }
568 }
569
570 // Find out if a method "m" with superclass "super", loader "classloader" and
571 // name "classname" needs a new vtable entry. Let P be a class package defined
572 // by "classloader" and "classname".
573 // NOTE: The logic used here is very similar to the one used for computing
574 // the vtables indices for a method. We cannot directly use that function because,
575 // we allocate the InstanceKlass at load time, and that requires that the
576 // superclass has been loaded.
577 // However, the vtable entries are filled in at link time, and therefore
578 // the superclass' vtable may not yet have been filled in.
579 bool klassVtable::needs_new_vtable_entry(const methodHandle& target_method,
580 const Klass* super,
581 Handle classloader,
582 Symbol* classname,
583 AccessFlags class_flags,
584 u2 major_version,
585 TRAPS) {
586 if (class_flags.is_interface()) {
587 // Interfaces do not use vtables, except for java.lang.Object methods,
588 // so there is no point to assigning
589 // a vtable index to any of their local methods. If we refrain from doing this,
590 // we can use Method::_vtable_index to hold the itable index
591 return false;
592 }
593
594 if (target_method->is_final_method(class_flags) ||
595 // a final method never needs a new entry; final methods can be statically
596 // resolved and they have to be present in the vtable only if they override
597 // a super's method, in which case they re-use its entry
598 (target_method()->is_static()) ||
599 // static methods don't need to be in vtable
600 (target_method()->name() == vmSymbols::object_initializer_name())
601 // <init> is never called dynamically-bound
602 ) {
603 return false;
604 }
605
606 // Concrete interface methods do not need new entries, they override
607 // abstract method entries using default inheritance rules
608 if (target_method()->method_holder() != NULL &&
609 target_method()->method_holder()->is_interface() &&
610 !target_method()->is_abstract()) {
611 assert(target_method()->is_default_method() || target_method()->is_private(),
612 "unexpected interface method type");
613 return false;
614 }
615
616 // we need a new entry if there is no superclass
617 if (super == NULL) {
618 return true;
619 }
620
621 // private methods in classes always have a new entry in the vtable.
622 // Specification interpretation since classic has private methods not overriding.
623 if (target_method()->is_private()) {
624 return true;
625 }
626
627 // Package private methods always need a new entry to root their own
628 // overriding. This allows transitive overriding to work.
629 if (target_method()->is_package_private()) {
630 return true;
631 }
632
633 // search through the super class hierarchy to see if we need
634 // a new entry
635 ResourceMark rm;
636 Symbol* name = target_method()->name();
637 Symbol* signature = target_method()->signature();
638 const Klass* k = super;
639 Method* super_method = NULL;
640 InstanceKlass *holder = NULL;
641 Method* recheck_method = NULL;
642 while (k != NULL) {
643 // lookup through the hierarchy for a method with matching name and sign.
644 super_method = InstanceKlass::cast(k)->lookup_method(name, signature);
645 if (super_method == NULL) {
646 break; // we still have to search for a matching miranda method
647 }
648 // get the class holding the matching method
649 // make sure you use that class for is_override
650 InstanceKlass* superk = super_method->method_holder();
651 // we want only instance method matches
652 // pretend private methods are not in the super vtable
653 // since we do override around them: e.g. a.m pub/b.m private/c.m pub,
654 // ignore private, c.m pub does override a.m pub
655 // For classes that were not javac'd together, we also do transitive overriding around
656 // methods that have less accessibility
657 if ((!super_method->is_static()) &&
658 (!super_method->is_private())) {
659 if (superk->is_override(super_method, classloader, classname, THREAD)) {
660 return false;
661 // else keep looking for transitive overrides
662 }
663 }
664
665 // Start with lookup result and continue to search up, for versions supporting transitive override
666 if (major_version >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) {
667 k = superk->super(); // haven't found an override match yet; continue to look
668 } else {
669 break;
670 }
671 }
672
673 // if the target method is public or protected it may have a matching
674 // miranda method in the super, whose entry it should re-use.
675 // Actually, to handle cases that javac would not generate, we need
676 // this check for all access permissions.
677 const InstanceKlass *sk = InstanceKlass::cast(super);
678 if (sk->has_miranda_methods()) {
679 if (sk->lookup_method_in_all_interfaces(name, signature, Klass::find_defaults) != NULL) {
680 return false; // found a matching miranda; we do not need a new entry
681 }
682 }
683 return true; // found no match; we need a new entry
684 }
685
686 // Support for miranda methods
687
688 // get the vtable index of a miranda method with matching "name" and "signature"
689 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) {
690 // search from the bottom, might be faster
691 for (int i = (length() - 1); i >= 0; i--) {
692 Method* m = table()[i].method();
693 if (is_miranda_entry_at(i) &&
694 m->name() == name && m->signature() == signature) {
695 return i;
696 }
697 }
698 return Method::invalid_vtable_index;
699 }
700
701 // check if an entry at an index is miranda
702 // requires that method m at entry be declared ("held") by an interface.
703 bool klassVtable::is_miranda_entry_at(int i) {
704 Method* m = method_at(i);
705 Klass* method_holder = m->method_holder();
706 InstanceKlass *mhk = InstanceKlass::cast(method_holder);
707
708 // miranda methods are public abstract instance interface methods in a class's vtable
709 if (mhk->is_interface()) {
710 assert(m->is_public(), "should be public");
711 assert(ik()->implements_interface(method_holder) , "this class should implement the interface");
712 if (is_miranda(m, ik()->methods(), ik()->default_methods(), ik()->super())) {
713 return true;
714 }
715 }
716 return false;
717 }
718
719 // Check if a method is a miranda method, given a class's methods array,
720 // its default_method table and its super class.
721 // "Miranda" means an abstract non-private method that would not be
722 // overridden for the local class.
723 // A "miranda" method should only include non-private interface
724 // instance methods, i.e. not private methods, not static methods,
725 // not default methods (concrete interface methods), not overpass methods.
726 // If a given class already has a local (including overpass) method, a
727 // default method, or any of its superclasses has the same which would have
728 // overridden an abstract method, then this is not a miranda method.
729 //
730 // Miranda methods are checked multiple times.
731 // Pass 1: during class load/class file parsing: before vtable size calculation:
732 // include superinterface abstract and default methods (non-private instance).
733 // We include potential default methods to give them space in the vtable.
734 // During the first run, the current instanceKlass has not yet been
735 // created, the superclasses and superinterfaces do have instanceKlasses
736 // but may not have vtables, the default_methods list is empty, no overpasses.
737 // This is seen by default method creation.
738 //
739 // Pass 2: recalculated during vtable initialization: only include abstract methods.
740 // The goal of pass 2 is to walk through the superinterfaces to see if any of
741 // the superinterface methods (which were all abstract pre-default methods)
742 // need to be added to the vtable.
743 // With the addition of default methods, we have three new challenges:
744 // overpasses, static interface methods and private interface methods.
745 // Static and private interface methods do not get added to the vtable and
746 // are not seen by the method resolution process, so we skip those.
747 // Overpass methods are already in the vtable, so vtable lookup will
748 // find them and we don't need to add a miranda method to the end of
749 // the vtable. So we look for overpass methods and if they are found we
750 // return false. Note that we inherit our superclasses vtable, so
751 // the superclass' search also needs to use find_overpass so that if
752 // one is found we return false.
753 // False means - we don't need a miranda method added to the vtable.
754 //
755 // During the second run, default_methods is set up, so concrete methods from
756 // superinterfaces with matching names/signatures to default_methods are already
757 // in the default_methods list and do not need to be appended to the vtable
758 // as mirandas. Abstract methods may already have been handled via
759 // overpasses - either local or superclass overpasses, which may be
760 // in the vtable already.
761 //
762 // Pass 3: They are also checked by link resolution and selection,
763 // for invocation on a method (not interface method) reference that
764 // resolves to a method with an interface as its method_holder.
765 // Used as part of walking from the bottom of the vtable to find
766 // the vtable index for the miranda method.
767 //
768 // Part of the Miranda Rights in the US mean that if you do not have
769 // an attorney one will be appointed for you.
770 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods,
771 Array<Method*>* default_methods, const Klass* super) {
772 if (m->is_static() || m->is_private() || m->is_overpass()) {
773 return false;
774 }
775 Symbol* name = m->name();
776 Symbol* signature = m->signature();
777
778 // First look in local methods to see if already covered
779 if (InstanceKlass::find_local_method(class_methods, name, signature,
780 Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL)
781 {
782 return false;
783 }
784
785 // Check local default methods
786 if ((default_methods != NULL) &&
787 (InstanceKlass::find_method(default_methods, name, signature) != NULL))
788 {
789 return false;
790 }
791
792 // Iterate on all superclasses, which should be InstanceKlasses.
793 // Note that we explicitly look for overpasses at each level.
794 // Overpasses may or may not exist for supers for pass 1,
795 // they should have been created for pass 2 and later.
796
797 for (const Klass* cursuper = super; cursuper != NULL; cursuper = cursuper->super())
798 {
799 if (InstanceKlass::cast(cursuper)->find_local_method(name, signature,
800 Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL) {
801 return false;
802 }
803 }
804
805 return true;
806 }
807
808 // Scans current_interface_methods for miranda methods that do not
809 // already appear in new_mirandas, or default methods, and are also not defined-and-non-private
810 // in super (superclass). These mirandas are added to all_mirandas if it is
811 // not null; in addition, those that are not duplicates of miranda methods
812 // inherited by super from its interfaces are added to new_mirandas.
813 // Thus, new_mirandas will be the set of mirandas that this class introduces,
814 // all_mirandas will be the set of all mirandas applicable to this class
815 // including all defined in superclasses.
816 void klassVtable::add_new_mirandas_to_lists(
817 GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas,
818 Array<Method*>* current_interface_methods, Array<Method*>* class_methods,
819 Array<Method*>* default_methods, const Klass* super) {
820
821 // iterate thru the current interface's method to see if it a miranda
822 int num_methods = current_interface_methods->length();
823 for (int i = 0; i < num_methods; i++) {
824 Method* im = current_interface_methods->at(i);
825 bool is_duplicate = false;
826 int num_of_current_mirandas = new_mirandas->length();
827 // check for duplicate mirandas in different interfaces we implement
828 for (int j = 0; j < num_of_current_mirandas; j++) {
829 Method* miranda = new_mirandas->at(j);
830 if ((im->name() == miranda->name()) &&
831 (im->signature() == miranda->signature())) {
832 is_duplicate = true;
833 break;
834 }
835 }
836
837 if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable
838 if (is_miranda(im, class_methods, default_methods, super)) { // is it a miranda at all?
839 const InstanceKlass *sk = InstanceKlass::cast(super);
840 // check if it is a duplicate of a super's miranda
841 if (sk->lookup_method_in_all_interfaces(im->name(), im->signature(), Klass::find_defaults) == NULL) {
842 new_mirandas->append(im);
843 }
844 if (all_mirandas != NULL) {
845 all_mirandas->append(im);
846 }
847 }
848 }
849 }
850 }
851
852 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas,
853 GrowableArray<Method*>* all_mirandas,
854 const Klass* super,
855 Array<Method*>* class_methods,
856 Array<Method*>* default_methods,
857 Array<Klass*>* local_interfaces) {
858 assert((new_mirandas->length() == 0) , "current mirandas must be 0");
859
860 // iterate thru the local interfaces looking for a miranda
861 int num_local_ifs = local_interfaces->length();
862 for (int i = 0; i < num_local_ifs; i++) {
863 InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i));
864 add_new_mirandas_to_lists(new_mirandas, all_mirandas,
865 ik->methods(), class_methods,
866 default_methods, super);
867 // iterate thru each local's super interfaces
868 Array<Klass*>* super_ifs = ik->transitive_interfaces();
869 int num_super_ifs = super_ifs->length();
870 for (int j = 0; j < num_super_ifs; j++) {
871 InstanceKlass *sik = InstanceKlass::cast(super_ifs->at(j));
872 add_new_mirandas_to_lists(new_mirandas, all_mirandas,
873 sik->methods(), class_methods,
874 default_methods, super);
875 }
876 }
877 }
878
879 // Discover miranda methods ("miranda" = "interface abstract, no binding"),
880 // and append them into the vtable starting at index initialized,
881 // return the new value of initialized.
882 // Miranda methods use vtable entries, but do not get assigned a vtable_index
883 // The vtable_index is discovered by searching from the end of the vtable
884 int klassVtable::fill_in_mirandas(int initialized) {
885 GrowableArray<Method*> mirandas(20);
886 get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(),
887 ik()->default_methods(), ik()->local_interfaces());
888 for (int i = 0; i < mirandas.length(); i++) {
889 if (log_develop_is_enabled(Trace, vtables)) {
890 Method* meth = mirandas.at(i);
891 ResourceMark rm(Thread::current());
892 LogTarget(Trace, vtables) lt;
893 LogStream ls(lt);
894 if (meth != NULL) {
895 char* sig = meth->name_and_sig_as_C_string();
896 ls.print("fill in mirandas with %s index %d, flags: ",
897 sig, initialized);
898 meth->print_linkage_flags(&ls);
899 ls.cr();
900 }
901 }
902 put_method_at(mirandas.at(i), initialized);
903 ++initialized;
904 }
905 return initialized;
906 }
907
908 // Copy this class's vtable to the vtable beginning at start.
909 // Used to copy superclass vtable to prefix of subclass's vtable.
910 void klassVtable::copy_vtable_to(vtableEntry* start) {
911 Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size());
912 }
913
914 #if INCLUDE_JVMTI
915 bool klassVtable::adjust_default_method(int vtable_index, Method* old_method, Method* new_method) {
916 // If old_method is default, find this vtable index in default_vtable_indices
917 // and replace that method in the _default_methods list
918 bool updated = false;
919
920 Array<Method*>* default_methods = ik()->default_methods();
921 if (default_methods != NULL) {
922 int len = default_methods->length();
923 for (int idx = 0; idx < len; idx++) {
924 if (vtable_index == ik()->default_vtable_indices()->at(idx)) {
925 if (default_methods->at(idx) == old_method) {
926 default_methods->at_put(idx, new_method);
927 updated = true;
928 }
929 break;
930 }
931 }
932 }
933 return updated;
934 }
935
936 // search the vtable for uses of either obsolete or EMCP methods
937 void klassVtable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) {
938 int prn_enabled = 0;
939 for (int index = 0; index < length(); index++) {
940 Method* old_method = unchecked_method_at(index);
941 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) {
942 continue; // skip uninteresting entries
943 }
944 assert(!old_method->is_deleted(), "vtable methods may not be deleted");
945
946 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum());
947
948 assert(new_method != NULL, "method_with_idnum() should not be NULL");
949 assert(old_method != new_method, "sanity check");
950
951 put_method_at(new_method, index);
952 // For default methods, need to update the _default_methods array
953 // which can only have one method entry for a given signature
954 bool updated_default = false;
955 if (old_method->is_default_method()) {
956 updated_default = adjust_default_method(index, old_method, new_method);
957 }
958
959 if (log_is_enabled(Info, redefine, class, update)) {
960 ResourceMark rm;
961 if (!(*trace_name_printed)) {
962 log_info(redefine, class, update)
963 ("adjust: klassname=%s for methods from name=%s",
964 _klass->external_name(), old_method->method_holder()->external_name());
965 *trace_name_printed = true;
966 }
967 log_debug(redefine, class, update, vtables)
968 ("vtable method update: %s(%s), updated default = %s",
969 new_method->name()->as_C_string(), new_method->signature()->as_C_string(), updated_default ? "true" : "false");
970 }
971 }
972 }
973
974 // a vtable should never contain old or obsolete methods
975 bool klassVtable::check_no_old_or_obsolete_entries() {
976 for (int i = 0; i < length(); i++) {
977 Method* m = unchecked_method_at(i);
978 if (m != NULL &&
979 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
980 return false;
981 }
982 }
983 return true;
984 }
985
986 void klassVtable::dump_vtable() {
987 tty->print_cr("vtable dump --");
988 for (int i = 0; i < length(); i++) {
989 Method* m = unchecked_method_at(i);
990 if (m != NULL) {
991 tty->print(" (%5d) ", i);
992 m->access_flags().print_on(tty);
993 if (m->is_default_method()) {
994 tty->print("default ");
995 }
996 if (m->is_overpass()) {
997 tty->print("overpass");
998 }
999 tty->print(" -- ");
1000 m->print_name(tty);
1001 tty->cr();
1002 }
1003 }
1004 }
1005 #endif // INCLUDE_JVMTI
1006
1007 // CDS/RedefineClasses support - clear vtables so they can be reinitialized
1008 void klassVtable::clear_vtable() {
1009 for (int i = 0; i < _length; i++) table()[i].clear();
1010 }
1011
1012 bool klassVtable::is_initialized() {
1013 return _length == 0 || table()[0].method() != NULL;
1014 }
1015
1016 //-----------------------------------------------------------------------------------------
1017 // Itable code
1018
1019 // Initialize a itableMethodEntry
1020 void itableMethodEntry::initialize(Method* m) {
1021 if (m == NULL) return;
1022
1023 #ifdef ASSERT
1024 if (MetaspaceShared::is_in_shared_space((void*)&_method) &&
1025 !MetaspaceShared::remapped_readwrite()) {
1026 // At runtime initialize_itable is rerun as part of link_class_impl()
1027 // for a shared class loaded by the non-boot loader.
1028 // The dumptime itable method entry should be the same as the runtime entry.
1029 assert(_method == m, "sanity");
1030 }
1031 #endif
1032 _method = m;
1033 }
1034
1035 klassItable::klassItable(InstanceKlass* klass) {
1036 _klass = klass;
1037
1038 if (klass->itable_length() > 0) {
1039 itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable();
1040 if (offset_entry != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized
1041 // First offset entry points to the first method_entry
1042 intptr_t* method_entry = (intptr_t *)(((address)klass) + offset_entry->offset());
1043 intptr_t* end = klass->end_of_itable();
1044
1045 _table_offset = (intptr_t*)offset_entry - (intptr_t*)klass;
1046 _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size();
1047 _size_method_table = (end - method_entry) / itableMethodEntry::size();
1048 assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation");
1049 return;
1050 }
1051 }
1052
1053 // The length of the itable was either zero, or it has not yet been initialized.
1054 _table_offset = 0;
1055 _size_offset_table = 0;
1056 _size_method_table = 0;
1057 }
1058
1059 static int initialize_count = 0;
1060
1061 // Initialization
1062 void klassItable::initialize_itable(bool checkconstraints, TRAPS) {
1063 if (_klass->is_interface()) {
1064 // This needs to go after vtable indices are assigned but
1065 // before implementors need to know the number of itable indices.
1066 assign_itable_indices_for_interface(_klass);
1067 }
1068
1069 // Cannot be setup doing bootstrapping, interfaces don't have
1070 // itables, and klass with only ones entry have empty itables
1071 if (Universe::is_bootstrapping() ||
1072 _klass->is_interface() ||
1073 _klass->itable_length() == itableOffsetEntry::size()) return;
1074
1075 // There's alway an extra itable entry so we can null-terminate it.
1076 guarantee(size_offset_table() >= 1, "too small");
1077 int num_interfaces = size_offset_table() - 1;
1078 if (num_interfaces > 0) {
1079 log_develop_debug(itables)("%3d: Initializing itables for %s", ++initialize_count,
1080 _klass->name()->as_C_string());
1081
1082
1083 // Iterate through all interfaces
1084 int i;
1085 for(i = 0; i < num_interfaces; i++) {
1086 itableOffsetEntry* ioe = offset_entry(i);
1087 HandleMark hm(THREAD);
1088 Klass* interf = ioe->interface_klass();
1089 assert(interf != NULL && ioe->offset() != 0, "bad offset entry in itable");
1090 initialize_itable_for_interface(ioe->offset(), interf, checkconstraints, CHECK);
1091 }
1092
1093 }
1094 // Check that the last entry is empty
1095 itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1);
1096 guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing");
1097 }
1098
1099
1100 inline bool interface_method_needs_itable_index(Method* m) {
1101 if (m->is_static()) return false; // e.g., Stream.empty
1102 if (m->is_initializer()) return false; // <init> or <clinit>
1103 if (m->is_private()) return false; // requires invokeSpecial
1104 // If an interface redeclares a method from java.lang.Object,
1105 // it should already have a vtable index, don't touch it.
1106 // e.g., CharSequence.toString (from initialize_vtable)
1107 // if (m->has_vtable_index()) return false; // NO!
1108 return true;
1109 }
1110
1111 int klassItable::assign_itable_indices_for_interface(Klass* klass) {
1112 // an interface does not have an itable, but its methods need to be numbered
1113 log_develop_debug(itables)("%3d: Initializing itable indices for interface %s",
1114 ++initialize_count, klass->name()->as_C_string());
1115 Array<Method*>* methods = InstanceKlass::cast(klass)->methods();
1116 int nof_methods = methods->length();
1117 int ime_num = 0;
1118 for (int i = 0; i < nof_methods; i++) {
1119 Method* m = methods->at(i);
1120 if (interface_method_needs_itable_index(m)) {
1121 assert(!m->is_final_method(), "no final interface methods");
1122 // If m is already assigned a vtable index, do not disturb it.
1123 if (log_develop_is_enabled(Trace, itables)) {
1124 ResourceMark rm;
1125 LogTarget(Trace, itables) lt;
1126 LogStream ls(lt);
1127 assert(m != NULL, "methods can never be null");
1128 const char* sig = m->name_and_sig_as_C_string();
1129 if (m->has_vtable_index()) {
1130 ls.print("vtable index %d for method: %s, flags: ", m->vtable_index(), sig);
1131 } else {
1132 ls.print("itable index %d for method: %s, flags: ", ime_num, sig);
1133 }
1134 m->print_linkage_flags(&ls);
1135 ls.cr();
1136 }
1137 if (!m->has_vtable_index()) {
1138 // A shared method could have an initialized itable_index that
1139 // is < 0.
1140 assert(m->vtable_index() == Method::pending_itable_index ||
1141 m->is_shared(),
1142 "set by initialize_vtable");
1143 m->set_itable_index(ime_num);
1144 // Progress to next itable entry
1145 ime_num++;
1146 }
1147 }
1148 }
1149 assert(ime_num == method_count_for_interface(klass), "proper sizing");
1150 return ime_num;
1151 }
1152
1153 int klassItable::method_count_for_interface(Klass* interf) {
1154 assert(interf->is_instance_klass(), "must be");
1155 assert(interf->is_interface(), "must be");
1156 Array<Method*>* methods = InstanceKlass::cast(interf)->methods();
1157 int nof_methods = methods->length();
1158 int length = 0;
1159 while (nof_methods > 0) {
1160 Method* m = methods->at(nof_methods-1);
1161 if (m->has_itable_index()) {
1162 length = m->itable_index() + 1;
1163 break;
1164 }
1165 nof_methods -= 1;
1166 }
1167 #ifdef ASSERT
1168 int nof_methods_copy = nof_methods;
1169 while (nof_methods_copy > 0) {
1170 Method* mm = methods->at(--nof_methods_copy);
1171 assert(!mm->has_itable_index() || mm->itable_index() < length, "");
1172 }
1173 #endif //ASSERT
1174 // return the rightmost itable index, plus one; or 0 if no methods have
1175 // itable indices
1176 return length;
1177 }
1178
1179
1180 void klassItable::initialize_itable_for_interface(int method_table_offset, Klass* interf, bool checkconstraints, TRAPS) {
1181 Array<Method*>* methods = InstanceKlass::cast(interf)->methods();
1182 int nof_methods = methods->length();
1183 HandleMark hm;
1184 assert(nof_methods > 0, "at least one method must exist for interface to be in vtable");
1185 Handle interface_loader (THREAD, InstanceKlass::cast(interf)->class_loader());
1186
1187 int ime_count = method_count_for_interface(interf);
1188 for (int i = 0; i < nof_methods; i++) {
1189 Method* m = methods->at(i);
1190 methodHandle target;
1191 if (m->has_itable_index()) {
1192 // This search must match the runtime resolution, i.e. selection search for invokeinterface
1193 // to correctly enforce loader constraints for interface method inheritance
1194 target = LinkResolver::lookup_instance_method_in_klasses(_klass, m->name(), m->signature(), CHECK);
1195 }
1196 if (target == NULL || !target->is_public() || target->is_abstract()) {
1197 // Entry does not resolve. Leave it empty for AbstractMethodError.
1198 if (!(target == NULL) && !target->is_public()) {
1199 // Stuff an IllegalAccessError throwing method in there instead.
1200 itableOffsetEntry::method_entry(_klass, method_table_offset)[m->itable_index()].
1201 initialize(Universe::throw_illegal_access_error());
1202 }
1203 } else {
1204 // Entry did resolve, check loader constraints before initializing
1205 // if checkconstraints requested
1206 if (checkconstraints) {
1207 Handle method_holder_loader (THREAD, target->method_holder()->class_loader());
1208 if (method_holder_loader() != interface_loader()) {
1209 ResourceMark rm(THREAD);
1210 Symbol* failed_type_symbol =
1211 SystemDictionary::check_signature_loaders(m->signature(),
1212 method_holder_loader,
1213 interface_loader,
1214 true, CHECK);
1215 if (failed_type_symbol != NULL) {
1216 const char* msg = "loader constraint violation in interface "
1217 "itable initialization: when resolving method \"%s\" the class"
1218 " loader (instance of %s) of the current class, %s, "
1219 "and the class loader (instance of %s) for interface "
1220 "%s have different Class objects for the type %s "
1221 "used in the signature";
1222 char* sig = target()->name_and_sig_as_C_string();
1223 const char* loader1 = SystemDictionary::loader_name(method_holder_loader());
1224 char* current = _klass->name()->as_C_string();
1225 const char* loader2 = SystemDictionary::loader_name(interface_loader());
1226 char* iface = InstanceKlass::cast(interf)->name()->as_C_string();
1227 char* failed_type_name = failed_type_symbol->as_C_string();
1228 size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) +
1229 strlen(current) + strlen(loader2) + strlen(iface) +
1230 strlen(failed_type_name);
1231 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
1232 jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2,
1233 iface, failed_type_name);
1234 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
1235 }
1236 }
1237 }
1238
1239 // ime may have moved during GC so recalculate address
1240 int ime_num = m->itable_index();
1241 assert(ime_num < ime_count, "oob");
1242 itableOffsetEntry::method_entry(_klass, method_table_offset)[ime_num].initialize(target());
1243 if (log_develop_is_enabled(Trace, itables)) {
1244 ResourceMark rm(THREAD);
1245 if (target() != NULL) {
1246 LogTarget(Trace, itables) lt;
1247 LogStream ls(lt);
1248 char* sig = target()->name_and_sig_as_C_string();
1249 ls.print("interface: %s, ime_num: %d, target: %s, method_holder: %s ",
1250 interf->internal_name(), ime_num, sig,
1251 target()->method_holder()->internal_name());
1252 ls.print("target_method flags: ");
1253 target()->print_linkage_flags(&ls);
1254 ls.cr();
1255 }
1256 }
1257 }
1258 }
1259 }
1260
1261 #if INCLUDE_JVMTI
1262 // search the itable for uses of either obsolete or EMCP methods
1263 void klassItable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) {
1264
1265 itableMethodEntry* ime = method_entry(0);
1266 for (int i = 0; i < _size_method_table; i++, ime++) {
1267 Method* old_method = ime->method();
1268 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) {
1269 continue; // skip uninteresting entries
1270 }
1271 assert(!old_method->is_deleted(), "itable methods may not be deleted");
1272
1273 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum());
1274
1275 assert(new_method != NULL, "method_with_idnum() should not be NULL");
1276 assert(old_method != new_method, "sanity check");
1277
1278 ime->initialize(new_method);
1279
1280 if (log_is_enabled(Info, redefine, class, update)) {
1281 ResourceMark rm;
1282 if (!(*trace_name_printed)) {
1283 log_info(redefine, class, update)("adjust: name=%s", old_method->method_holder()->external_name());
1284 *trace_name_printed = true;
1285 }
1286 log_trace(redefine, class, update, itables)
1287 ("itable method update: %s(%s)", new_method->name()->as_C_string(), new_method->signature()->as_C_string());
1288 }
1289 }
1290 }
1291
1292 // an itable should never contain old or obsolete methods
1293 bool klassItable::check_no_old_or_obsolete_entries() {
1294 itableMethodEntry* ime = method_entry(0);
1295 for (int i = 0; i < _size_method_table; i++) {
1296 Method* m = ime->method();
1297 if (m != NULL &&
1298 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
1299 return false;
1300 }
1301 ime++;
1302 }
1303 return true;
1304 }
1305
1306 void klassItable::dump_itable() {
1307 itableMethodEntry* ime = method_entry(0);
1308 tty->print_cr("itable dump --");
1309 for (int i = 0; i < _size_method_table; i++) {
1310 Method* m = ime->method();
1311 if (m != NULL) {
1312 tty->print(" (%5d) ", i);
1313 m->access_flags().print_on(tty);
1314 if (m->is_default_method()) {
1315 tty->print("default ");
1316 }
1317 tty->print(" -- ");
1318 m->print_name(tty);
1319 tty->cr();
1320 }
1321 ime++;
1322 }
1323 }
1324 #endif // INCLUDE_JVMTI
1325
1326 // Setup
1327 class InterfaceVisiterClosure : public StackObj {
1328 public:
1329 virtual void doit(Klass* intf, int method_count) = 0;
1330 };
1331
1332 // Visit all interfaces with at least one itable method
1333 void visit_all_interfaces(Array<Klass*>* transitive_intf, InterfaceVisiterClosure *blk) {
1334 // Handle array argument
1335 for(int i = 0; i < transitive_intf->length(); i++) {
1336 Klass* intf = transitive_intf->at(i);
1337 assert(intf->is_interface(), "sanity check");
1338
1339 // Find no. of itable methods
1340 int method_count = 0;
1341 // method_count = klassItable::method_count_for_interface(intf);
1342 Array<Method*>* methods = InstanceKlass::cast(intf)->methods();
1343 if (methods->length() > 0) {
1344 for (int i = methods->length(); --i >= 0; ) {
1345 if (interface_method_needs_itable_index(methods->at(i))) {
1346 method_count++;
1347 }
1348 }
1349 }
1350
1351 // Only count interfaces with at least one method
1352 if (method_count > 0) {
1353 blk->doit(intf, method_count);
1354 }
1355 }
1356 }
1357
1358 class CountInterfacesClosure : public InterfaceVisiterClosure {
1359 private:
1360 int _nof_methods;
1361 int _nof_interfaces;
1362 public:
1363 CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; }
1364
1365 int nof_methods() const { return _nof_methods; }
1366 int nof_interfaces() const { return _nof_interfaces; }
1367
1368 void doit(Klass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; }
1369 };
1370
1371 class SetupItableClosure : public InterfaceVisiterClosure {
1372 private:
1373 itableOffsetEntry* _offset_entry;
1374 itableMethodEntry* _method_entry;
1375 address _klass_begin;
1376 public:
1377 SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) {
1378 _klass_begin = klass_begin;
1379 _offset_entry = offset_entry;
1380 _method_entry = method_entry;
1381 }
1382
1383 itableMethodEntry* method_entry() const { return _method_entry; }
1384
1385 void doit(Klass* intf, int method_count) {
1386 int offset = ((address)_method_entry) - _klass_begin;
1387 _offset_entry->initialize(intf, offset);
1388 _offset_entry++;
1389 _method_entry += method_count;
1390 }
1391 };
1392
1393 int klassItable::compute_itable_size(Array<Klass*>* transitive_interfaces) {
1394 // Count no of interfaces and total number of interface methods
1395 CountInterfacesClosure cic;
1396 visit_all_interfaces(transitive_interfaces, &cic);
1397
1398 // There's alway an extra itable entry so we can null-terminate it.
1399 int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods());
1400
1401 // Statistics
1402 update_stats(itable_size * wordSize);
1403
1404 return itable_size;
1405 }
1406
1407
1408 // Fill out offset table and interface klasses into the itable space
1409 void klassItable::setup_itable_offset_table(InstanceKlass* klass) {
1410 if (klass->itable_length() == 0) return;
1411 assert(!klass->is_interface(), "Should have zero length itable");
1412
1413 // Count no of interfaces and total number of interface methods
1414 CountInterfacesClosure cic;
1415 visit_all_interfaces(klass->transitive_interfaces(), &cic);
1416 int nof_methods = cic.nof_methods();
1417 int nof_interfaces = cic.nof_interfaces();
1418
1419 // Add one extra entry so we can null-terminate the table
1420 nof_interfaces++;
1421
1422 assert(compute_itable_size(klass->transitive_interfaces()) ==
1423 calc_itable_size(nof_interfaces, nof_methods),
1424 "mismatch calculation of itable size");
1425
1426 // Fill-out offset table
1427 itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable();
1428 itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces);
1429 intptr_t* end = klass->end_of_itable();
1430 assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)");
1431 assert((oop*)(end) == (oop*)(ime + nof_methods), "wrong offset calculation (2)");
1432
1433 // Visit all interfaces and initialize itable offset table
1434 SetupItableClosure sic((address)klass, ioe, ime);
1435 visit_all_interfaces(klass->transitive_interfaces(), &sic);
1436
1437 #ifdef ASSERT
1438 ime = sic.method_entry();
1439 oop* v = (oop*) klass->end_of_itable();
1440 assert( (oop*)(ime) == v, "wrong offset calculation (2)");
1441 #endif
1442 }
1443
1444
1445 // inverse to itable_index
1446 Method* klassItable::method_for_itable_index(Klass* intf, int itable_index) {
1447 assert(InstanceKlass::cast(intf)->is_interface(), "sanity check");
1448 assert(intf->verify_itable_index(itable_index), "");
1449 Array<Method*>* methods = InstanceKlass::cast(intf)->methods();
1450
1451 if (itable_index < 0 || itable_index >= method_count_for_interface(intf))
1452 return NULL; // help caller defend against bad indices
1453
1454 int index = itable_index;
1455 Method* m = methods->at(index);
1456 int index2 = -1;
1457 while (!m->has_itable_index() ||
1458 (index2 = m->itable_index()) != itable_index) {
1459 assert(index2 < itable_index, "monotonic");
1460 if (++index == methods->length())
1461 return NULL;
1462 m = methods->at(index);
1463 }
1464 assert(m->itable_index() == itable_index, "correct inverse");
1465
1466 return m;
1467 }
1468
1469 void klassVtable::verify(outputStream* st, bool forced) {
1470 // make sure table is initialized
1471 if (!Universe::is_fully_initialized()) return;
1472 #ifndef PRODUCT
1473 // avoid redundant verifies
1474 if (!forced && _verify_count == Universe::verify_count()) return;
1475 _verify_count = Universe::verify_count();
1476 #endif
1477 oop* end_of_obj = (oop*)_klass + _klass->size();
1478 oop* end_of_vtable = (oop *)&table()[_length];
1479 if (end_of_vtable > end_of_obj) {
1480 fatal("klass %s: klass object too short (vtable extends beyond end)",
1481 _klass->internal_name());
1482 }
1483
1484 for (int i = 0; i < _length; i++) table()[i].verify(this, st);
1485 // verify consistency with superKlass vtable
1486 Klass* super = _klass->super();
1487 if (super != NULL) {
1488 InstanceKlass* sk = InstanceKlass::cast(super);
1489 klassVtable vt = sk->vtable();
1490 for (int i = 0; i < vt.length(); i++) {
1491 verify_against(st, &vt, i);
1492 }
1493 }
1494 }
1495
1496 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) {
1497 vtableEntry* vte = &vt->table()[index];
1498 if (vte->method()->name() != table()[index].method()->name() ||
1499 vte->method()->signature() != table()[index].method()->signature()) {
1500 fatal("mismatched name/signature of vtable entries");
1501 }
1502 }
1503
1504 #ifndef PRODUCT
1505 void klassVtable::print() {
1506 ResourceMark rm;
1507 tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length());
1508 for (int i = 0; i < length(); i++) {
1509 table()[i].print();
1510 tty->cr();
1511 }
1512 }
1513 #endif
1514
1515 void vtableEntry::verify(klassVtable* vt, outputStream* st) {
1516 NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true));
1517 Klass* vtklass = vt->klass();
1518 if (vtklass->is_instance_klass() &&
1519 (InstanceKlass::cast(vtklass)->major_version() >= klassVtable::VTABLE_TRANSITIVE_OVERRIDE_VERSION)) {
1520 assert(method() != NULL, "must have set method");
1521 }
1522 if (method() != NULL) {
1523 method()->verify();
1524 // we sub_type, because it could be a miranda method
1525 if (!vtklass->is_subtype_of(method()->method_holder())) {
1526 #ifndef PRODUCT
1527 print();
1528 #endif
1529 fatal("vtableEntry " PTR_FORMAT ": method is from subclass", p2i(this));
1530 }
1531 }
1532 }
1533
1534 #ifndef PRODUCT
1535
1536 void vtableEntry::print() {
1537 ResourceMark rm;
1538 tty->print("vtableEntry %s: ", method()->name()->as_C_string());
1539 if (Verbose) {
1540 tty->print("m " PTR_FORMAT " ", p2i(method()));
1541 }
1542 }
1543
1544 class VtableStats : AllStatic {
1545 public:
1546 static int no_klasses; // # classes with vtables
1547 static int no_array_klasses; // # array classes
1548 static int no_instance_klasses; // # instanceKlasses
1549 static int sum_of_vtable_len; // total # of vtable entries
1550 static int sum_of_array_vtable_len; // total # of vtable entries in array klasses only
1551 static int fixed; // total fixed overhead in bytes
1552 static int filler; // overhead caused by filler bytes
1553 static int entries; // total bytes consumed by vtable entries
1554 static int array_entries; // total bytes consumed by array vtable entries
1555
1556 static void do_class(Klass* k) {
1557 Klass* kl = k;
1558 klassVtable vt = kl->vtable();
1559 no_klasses++;
1560 if (kl->is_instance_klass()) {
1561 no_instance_klasses++;
1562 kl->array_klasses_do(do_class);
1563 }
1564 if (kl->is_array_klass()) {
1565 no_array_klasses++;
1566 sum_of_array_vtable_len += vt.length();
1567 }
1568 sum_of_vtable_len += vt.length();
1569 }
1570
1571 static void compute() {
1572 ClassLoaderDataGraph::classes_do(do_class);
1573 fixed = no_klasses * oopSize; // vtable length
1574 // filler size is a conservative approximation
1575 filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(InstanceKlass) - sizeof(ArrayKlass) - 1);
1576 entries = sizeof(vtableEntry) * sum_of_vtable_len;
1577 array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len;
1578 }
1579 };
1580
1581 int VtableStats::no_klasses = 0;
1582 int VtableStats::no_array_klasses = 0;
1583 int VtableStats::no_instance_klasses = 0;
1584 int VtableStats::sum_of_vtable_len = 0;
1585 int VtableStats::sum_of_array_vtable_len = 0;
1586 int VtableStats::fixed = 0;
1587 int VtableStats::filler = 0;
1588 int VtableStats::entries = 0;
1589 int VtableStats::array_entries = 0;
1590
1591 void klassVtable::print_statistics() {
1592 ResourceMark rm;
1593 HandleMark hm;
1594 VtableStats::compute();
1595 tty->print_cr("vtable statistics:");
1596 tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses);
1597 int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries;
1598 tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed);
1599 tty->print_cr("%6d bytes filler overhead", VtableStats::filler);
1600 tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries);
1601 tty->print_cr("%6d bytes total", total);
1602 }
1603
1604 int klassItable::_total_classes; // Total no. of classes with itables
1605 long klassItable::_total_size; // Total no. of bytes used for itables
1606
1607 void klassItable::print_statistics() {
1608 tty->print_cr("itable statistics:");
1609 tty->print_cr("%6d classes with itables", _total_classes);
1610 tty->print_cr("%6lu K uses for itables (average by class: %ld bytes)", _total_size / K, _total_size / _total_classes);
1611 }
1612
1613 #endif // PRODUCT