1 /*
2 * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "jvm.h"
27 #include "classfile/systemDictionary.hpp"
28 #include "classfile/vmSymbols.hpp"
29 #include "gc/shared/gcLocker.hpp"
30 #include "logging/log.hpp"
31 #include "logging/logStream.hpp"
32 #include "memory/metaspaceShared.hpp"
33 #include "memory/resourceArea.hpp"
34 #include "memory/universe.inline.hpp"
35 #include "oops/instanceKlass.hpp"
36 #include "oops/klassVtable.hpp"
37 #include "oops/method.hpp"
38 #include "oops/objArrayOop.hpp"
39 #include "oops/oop.inline.hpp"
40 #include "runtime/arguments.hpp"
41 #include "runtime/handles.inline.hpp"
42 #include "utilities/copy.hpp"
43
44 inline InstanceKlass* klassVtable::ik() const {
45 return InstanceKlass::cast(_klass);
46 }
47
48 bool klassVtable::is_preinitialized_vtable() {
49 return _klass->is_shared() && !MetaspaceShared::remapped_readwrite();
50 }
51
52
53 // this function computes the vtable size (including the size needed for miranda
54 // methods) and the number of miranda methods in this class.
55 // Note on Miranda methods: Let's say there is a class C that implements
56 // interface I, and none of C's superclasses implements I.
57 // Let's say there is an abstract method m in I that neither C
58 // nor any of its super classes implement (i.e there is no method of any access,
59 // with the same name and signature as m), then m is a Miranda method which is
60 // entered as a public abstract method in C's vtable. From then on it should
61 // treated as any other public method in C for method over-ride purposes.
62 void klassVtable::compute_vtable_size_and_num_mirandas(
63 int* vtable_length_ret, int* num_new_mirandas,
64 GrowableArray<Method*>* all_mirandas, const Klass* super,
65 Array<Method*>* methods, AccessFlags class_flags, u2 major_version,
66 Handle classloader, Symbol* classname, Array<Klass*>* local_interfaces,
67 TRAPS) {
68 NoSafepointVerifier nsv;
69
70 // set up default result values
71 int vtable_length = 0;
72
73 // start off with super's vtable length
74 vtable_length = super == NULL ? 0 : super->vtable_length();
75
76 // go thru each method in the methods table to see if it needs a new entry
77 int len = methods->length();
78 for (int i = 0; i < len; i++) {
79 assert(methods->at(i)->is_method(), "must be a Method*");
80 methodHandle mh(THREAD, methods->at(i));
81
82 if (needs_new_vtable_entry(mh, super, classloader, classname, class_flags, major_version, THREAD)) {
83 vtable_length += vtableEntry::size(); // we need a new entry
84 }
85 }
86
87 GrowableArray<Method*> new_mirandas(20);
88 // compute the number of mirandas methods that must be added to the end
89 get_mirandas(&new_mirandas, all_mirandas, super, methods, NULL, local_interfaces,
90 class_flags.is_interface());
91 *num_new_mirandas = new_mirandas.length();
92
93 // Interfaces do not need interface methods in their vtables
94 // This includes miranda methods and during later processing, default methods
95 if (!class_flags.is_interface()) {
96 vtable_length += *num_new_mirandas * vtableEntry::size();
97 }
98
99 if (Universe::is_bootstrapping() && vtable_length == 0 && classname != vmSymbols::java_lang____Value()) {
100 // array classes don't have their superclass set correctly during
101 // bootstrapping
102 vtable_length = Universe::base_vtable_size();
103 }
104
105 if (super == NULL && vtable_length != Universe::base_vtable_size()
106 && !class_flags.is_value_type()) {
107 if (Universe::is_bootstrapping()) {
108 // Someone is attempting to override java.lang.Object incorrectly on the
109 // bootclasspath. The JVM cannot recover from this error including throwing
110 // an exception
111 vm_exit_during_initialization("Incompatible definition of java.lang.Object");
112 } else {
113 // Someone is attempting to redefine java.lang.Object incorrectly. The
114 // only way this should happen is from
115 // SystemDictionary::resolve_from_stream(), which will detect this later
116 // and throw a security exception. So don't assert here to let
117 // the exception occur.
118 vtable_length = Universe::base_vtable_size();
119 }
120 }
121 assert(vtable_length % vtableEntry::size() == 0, "bad vtable length");
122 assert(vtable_length >= Universe::base_vtable_size()
123 || class_flags.is_value_type(), "vtable too small");
124
125 *vtable_length_ret = vtable_length;
126 }
127
128 int klassVtable::index_of(Method* m, int len) const {
129 assert(m->has_vtable_index(), "do not ask this of non-vtable methods");
130 return m->vtable_index();
131 }
132
133 // Copy super class's vtable to the first part (prefix) of this class's vtable,
134 // and return the number of entries copied. Expects that 'super' is the Java
135 // super class (arrays can have "array" super classes that must be skipped).
136 int klassVtable::initialize_from_super(Klass* super) {
137 if (super == NULL) {
138 return 0;
139 } else if (is_preinitialized_vtable()) {
140 // A shared class' vtable is preinitialized at dump time. No need to copy
141 // methods from super class for shared class, as that was already done
142 // during archiving time. However, if Jvmti has redefined a class,
143 // copy super class's vtable in case the super class has changed.
144 return super->vtable().length();
145 } else {
146 // copy methods from superKlass
147 klassVtable superVtable = super->vtable();
148 assert(superVtable.length() <= _length, "vtable too short");
149 #ifdef ASSERT
150 superVtable.verify(tty, true);
151 #endif
152 superVtable.copy_vtable_to(table());
153 if (log_develop_is_enabled(Trace, vtables)) {
154 ResourceMark rm;
155 log_develop_trace(vtables)("copy vtable from %s to %s size %d",
156 super->internal_name(), klass()->internal_name(),
157 _length);
158 }
159 return superVtable.length();
160 }
161 }
162
163 //
164 // Revised lookup semantics introduced 1.3 (Kestrel beta)
165 void klassVtable::initialize_vtable(bool checkconstraints, TRAPS) {
166
167 // Note: Arrays can have intermediate array supers. Use java_super to skip them.
168 Klass* super = _klass->java_super();
169 int nofNewEntries = 0;
170
171 bool is_shared = _klass->is_shared();
172
173 if (!_klass->is_array_klass()) {
174 ResourceMark rm(THREAD);
175 log_develop_debug(vtables)("Initializing: %s", _klass->name()->as_C_string());
176 }
177
178 #ifdef ASSERT
179 oop* end_of_obj = (oop*)_klass + _klass->size();
180 oop* end_of_vtable = (oop*)&table()[_length];
181 assert(end_of_vtable <= end_of_obj, "vtable extends beyond end");
182 #endif
183
184 if (Universe::is_bootstrapping()) {
185 assert(!is_shared, "sanity");
186 // just clear everything
187 for (int i = 0; i < _length; i++) table()[i].clear();
188 return;
189 }
190
191 int super_vtable_len = initialize_from_super(super);
192 if (_klass->is_array_klass()) {
193 assert(super_vtable_len == _length, "arrays shouldn't introduce new methods");
194 } else {
195 assert(_klass->is_instance_klass(), "must be InstanceKlass");
196
197 Array<Method*>* methods = ik()->methods();
198 int len = methods->length();
199 int initialized = super_vtable_len;
200
201 // Check each of this class's methods against super;
202 // if override, replace in copy of super vtable, otherwise append to end
203 for (int i = 0; i < len; i++) {
204 // update_inherited_vtable can stop for gc - ensure using handles
205 HandleMark hm(THREAD);
206 assert(methods->at(i)->is_method(), "must be a Method*");
207 methodHandle mh(THREAD, methods->at(i));
208
209 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, -1, checkconstraints, CHECK);
210
211 if (needs_new_entry) {
212 put_method_at(mh(), initialized);
213 mh()->set_vtable_index(initialized); // set primary vtable index
214 initialized++;
215 }
216 }
217
218 // update vtable with default_methods
219 Array<Method*>* default_methods = ik()->default_methods();
220 if (default_methods != NULL) {
221 len = default_methods->length();
222 if (len > 0) {
223 Array<int>* def_vtable_indices = NULL;
224 if ((def_vtable_indices = ik()->default_vtable_indices()) == NULL) {
225 assert(!is_shared, "shared class def_vtable_indices does not exist");
226 def_vtable_indices = ik()->create_new_default_vtable_indices(len, CHECK);
227 } else {
228 assert(def_vtable_indices->length() == len, "reinit vtable len?");
229 }
230 for (int i = 0; i < len; i++) {
231 HandleMark hm(THREAD);
232 assert(default_methods->at(i)->is_method(), "must be a Method*");
233 methodHandle mh(THREAD, default_methods->at(i));
234 assert(!mh->is_private(), "private interface method in the default method list");
235 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, i, checkconstraints, CHECK);
236
237 // needs new entry
238 if (needs_new_entry) {
239 put_method_at(mh(), initialized);
240 if (is_preinitialized_vtable()) {
241 // At runtime initialize_vtable is rerun for a shared class
242 // (loaded by the non-boot loader) as part of link_class_impl().
243 // The dumptime vtable index should be the same as the runtime index.
244 assert(def_vtable_indices->at(i) == initialized,
245 "dump time vtable index is different from runtime index");
246 } else {
247 def_vtable_indices->at_put(i, initialized); //set vtable index
248 }
249 initialized++;
250 }
251 }
252 }
253 }
254
255 // add miranda methods; it will also return the updated initialized
256 // Interfaces do not need interface methods in their vtables
257 // This includes miranda methods and during later processing, default methods
258 if (!ik()->is_interface()) {
259 initialized = fill_in_mirandas(initialized);
260 }
261
262 // In class hierarchies where the accessibility is not increasing (i.e., going from private ->
263 // package_private -> public/protected), the vtable might actually be smaller than our initial
264 // calculation, for classfile versions for which we do not do transitive override
265 // calculations.
266 if (ik()->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) {
267 assert(initialized == _length, "vtable initialization failed");
268 } else {
269 assert(initialized <= _length, "vtable initialization failed");
270 for(;initialized < _length; initialized++) {
271 table()[initialized].clear();
272 }
273 }
274 NOT_PRODUCT(verify(tty, true));
275 }
276 }
277
278 // Called for cases where a method does not override its superclass' vtable entry
279 // For bytecodes not produced by javac together it is possible that a method does not override
280 // the superclass's method, but might indirectly override a super-super class's vtable entry
281 // If none found, return a null superk, else return the superk of the method this does override
282 // For public and protected methods: if they override a superclass, they will
283 // also be overridden themselves appropriately.
284 // Private methods do not override and are not overridden.
285 // Package Private methods are trickier:
286 // e.g. P1.A, pub m
287 // P2.B extends A, package private m
288 // P1.C extends B, public m
289 // P1.C.m needs to override P1.A.m and can not override P2.B.m
290 // Therefore: all package private methods need their own vtable entries for
291 // them to be the root of an inheritance overriding decision
292 // Package private methods may also override other vtable entries
293 InstanceKlass* klassVtable::find_transitive_override(InstanceKlass* initialsuper, const methodHandle& target_method,
294 int vtable_index, Handle target_loader, Symbol* target_classname, Thread * THREAD) {
295 InstanceKlass* superk = initialsuper;
296 while (superk != NULL && superk->super() != NULL) {
297 InstanceKlass* supersuperklass = InstanceKlass::cast(superk->super());
298 klassVtable ssVtable = supersuperklass->vtable();
299 if (vtable_index < ssVtable.length()) {
300 Method* super_method = ssVtable.method_at(vtable_index);
301 #ifndef PRODUCT
302 Symbol* name= target_method()->name();
303 Symbol* signature = target_method()->signature();
304 assert(super_method->name() == name && super_method->signature() == signature, "vtable entry name/sig mismatch");
305 #endif
306 if (supersuperklass->is_override(super_method, target_loader, target_classname, THREAD)) {
307 if (log_develop_is_enabled(Trace, vtables)) {
308 ResourceMark rm(THREAD);
309 LogTarget(Trace, vtables) lt;
310 LogStream ls(lt);
311 char* sig = target_method()->name_and_sig_as_C_string();
312 ls.print("transitive overriding superclass %s with %s index %d, original flags: ",
313 supersuperklass->internal_name(),
314 sig, vtable_index);
315 super_method->print_linkage_flags(&ls);
316 ls.print("overriders flags: ");
317 target_method->print_linkage_flags(&ls);
318 ls.cr();
319 }
320
321 break; // return found superk
322 }
323 } else {
324 // super class has no vtable entry here, stop transitive search
325 superk = (InstanceKlass*)NULL;
326 break;
327 }
328 // if no override found yet, continue to search up
329 superk = superk->super() == NULL ? NULL : InstanceKlass::cast(superk->super());
330 }
331
332 return superk;
333 }
334
335 static void log_vtables(int i, bool overrides, const methodHandle& target_method,
336 Klass* target_klass, Method* super_method,
337 Thread* thread) {
338 #ifndef PRODUCT
339 if (log_develop_is_enabled(Trace, vtables)) {
340 ResourceMark rm(thread);
341 LogTarget(Trace, vtables) lt;
342 LogStream ls(lt);
343 char* sig = target_method()->name_and_sig_as_C_string();
344 if (overrides) {
345 ls.print("overriding with %s index %d, original flags: ",
346 sig, i);
347 } else {
348 ls.print("NOT overriding with %s index %d, original flags: ",
349 sig, i);
350 }
351 super_method->print_linkage_flags(&ls);
352 ls.print("overriders flags: ");
353 target_method->print_linkage_flags(&ls);
354 ls.cr();
355 }
356 #endif
357 }
358
359 // Update child's copy of super vtable for overrides
360 // OR return true if a new vtable entry is required.
361 // Only called for InstanceKlass's, i.e. not for arrays
362 // If that changed, could not use _klass as handle for klass
363 bool klassVtable::update_inherited_vtable(InstanceKlass* klass, const methodHandle& target_method,
364 int super_vtable_len, int default_index,
365 bool checkconstraints, TRAPS) {
366 ResourceMark rm;
367 bool allocate_new = true;
368 assert(klass->is_instance_klass(), "must be InstanceKlass");
369
370 Array<int>* def_vtable_indices = NULL;
371 bool is_default = false;
372
373 // default methods are non-private concrete methods in superinterfaces which are added
374 // to the vtable with their real method_holder.
375 // Since vtable and itable indices share the same storage, don't touch
376 // the default method's real vtable/itable index.
377 // default_vtable_indices stores the vtable value relative to this inheritor
378 if (default_index >= 0 ) {
379 is_default = true;
380 def_vtable_indices = klass->default_vtable_indices();
381 assert(!target_method()->is_private(), "private interface method flagged as default");
382 assert(def_vtable_indices != NULL, "def vtable alloc?");
383 assert(default_index <= def_vtable_indices->length(), "def vtable len?");
384 } else {
385 assert(klass == target_method()->method_holder(), "caller resp.");
386 // Initialize the method's vtable index to "nonvirtual".
387 // If we allocate a vtable entry, we will update it to a non-negative number.
388 target_method()->set_vtable_index(Method::nonvirtual_vtable_index);
389 }
390
391 // Static and <init> methods are never in
392 if (target_method()->is_static() || target_method()->name() == vmSymbols::object_initializer_name()) {
393 return false;
394 }
395
396 if (target_method->is_final_method(klass->access_flags())) {
397 // a final method never needs a new entry; final methods can be statically
398 // resolved and they have to be present in the vtable only if they override
399 // a super's method, in which case they re-use its entry
400 allocate_new = false;
401 } else if (klass->is_interface()) {
402 allocate_new = false; // see note below in needs_new_vtable_entry
403 // An interface never allocates new vtable slots, only inherits old ones.
404 // This method will either be assigned its own itable index later,
405 // or be assigned an inherited vtable index in the loop below.
406 // default methods inherited by classes store their vtable indices
407 // in the inheritor's default_vtable_indices.
408 // default methods inherited by interfaces may already have a
409 // valid itable index, if so, don't change it.
410 // Overpass methods in an interface will be assigned an itable index later
411 // by an inheriting class.
412 // Private interface methods have no itable index and are always invoked nonvirtually,
413 // so they retain their nonvirtual_vtable_index value, and therefore can_be_statically_bound()
414 // will return true.
415 if ((!is_default || !target_method()->has_itable_index()) && !target_method()->is_private()) {
416 target_method()->set_vtable_index(Method::pending_itable_index);
417 }
418 }
419
420 // we need a new entry if there is no superclass
421 Klass* super = klass->super();
422 if (super == NULL) {
423 return allocate_new;
424 }
425
426 // private methods in classes always have a new entry in the vtable
427 // specification interpretation since classic has
428 // private methods not overriding
429 // JDK8 adds private methods in interfaces which require invokespecial
430 if (target_method()->is_private()) {
431 return allocate_new;
432 }
433
434 // search through the vtable and update overridden entries
435 // Since check_signature_loaders acquires SystemDictionary_lock
436 // which can block for gc, once we are in this loop, use handles
437 // For classfiles built with >= jdk7, we now look for transitive overrides
438
439 Symbol* name = target_method()->name();
440 Symbol* signature = target_method()->signature();
441
442 Klass* target_klass = target_method()->method_holder();
443 if (target_klass == NULL) {
444 target_klass = _klass;
445 }
446
447 Handle target_loader(THREAD, target_klass->class_loader());
448
449 Symbol* target_classname = target_klass->name();
450 for(int i = 0; i < super_vtable_len; i++) {
451 Method* super_method;
452 if (is_preinitialized_vtable()) {
453 // If this is a shared class, the vtable is already in the final state (fully
454 // initialized). Need to look at the super's vtable.
455 klassVtable superVtable = super->vtable();
456 super_method = superVtable.method_at(i);
457 } else {
458 super_method = method_at(i);
459 }
460 // Check if method name matches. Ignore match if klass is an interface and the
461 // matching method is a non-public java.lang.Object method. (See JVMS 5.4.3.4)
462 // This is safe because the method at this slot should never get invoked.
463 // (TBD: put in a method to throw NoSuchMethodError if this slot is ever used.)
464 if (super_method->name() == name && super_method->signature() == signature &&
465 (!_klass->is_interface() ||
466 !SystemDictionary::is_nonpublic_Object_method(super_method))) {
467
468 // get super_klass for method_holder for the found method
469 InstanceKlass* super_klass = super_method->method_holder();
470
471 // Whether the method is being overridden
472 bool overrides = false;
473
474 // private methods are also never overridden
475 if (!super_method->is_private() &&
476 (is_default
477 || ((super_klass->is_override(super_method, target_loader, target_classname, THREAD))
478 || ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION)
479 && ((super_klass = find_transitive_override(super_klass,
480 target_method, i, target_loader,
481 target_classname, THREAD))
482 != (InstanceKlass*)NULL)))))
483 {
484 // Package private methods always need a new entry to root their own
485 // overriding. They may also override other methods.
486 if (!target_method()->is_package_private()) {
487 allocate_new = false;
488 }
489
490 // Do not check loader constraints for overpass methods because overpass
491 // methods are created by the jvm to throw exceptions.
492 if (checkconstraints && !target_method()->is_overpass()) {
493 // Override vtable entry if passes loader constraint check
494 // if loader constraint checking requested
495 // No need to visit his super, since he and his super
496 // have already made any needed loader constraints.
497 // Since loader constraints are transitive, it is enough
498 // to link to the first super, and we get all the others.
499 Handle super_loader(THREAD, super_klass->class_loader());
500
501 if (target_loader() != super_loader()) {
502 ResourceMark rm(THREAD);
503 Symbol* failed_type_symbol =
504 SystemDictionary::check_signature_loaders(signature, target_loader,
505 super_loader, true,
506 CHECK_(false));
507 if (failed_type_symbol != NULL) {
508 const char* msg = "loader constraint violation for class %s: when selecting "
509 "overriding method \"%s\" the class loader (instance of %s) of the "
510 "selected method's type %s, and the class loader (instance of %s) for its super "
511 "type %s have different Class objects for the type %s used in the signature";
512 char* curr_class = klass->name()->as_C_string();
513 char* sig = target_method()->name_and_sig_as_C_string();
514 const char* loader1 = SystemDictionary::loader_name(target_loader());
515 char* sel_class = target_klass->name()->as_C_string();
516 const char* loader2 = SystemDictionary::loader_name(super_loader());
517 char* super_class = super_klass->name()->as_C_string();
518 char* failed_type_name = failed_type_symbol->as_C_string();
519 size_t buflen = strlen(msg) + strlen(curr_class) + strlen(sig) +
520 strlen(loader1) + strlen(sel_class) + strlen(loader2) +
521 strlen(super_class) + strlen(failed_type_name);
522 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
523 jio_snprintf(buf, buflen, msg, curr_class, sig, loader1, sel_class, loader2,
524 super_class, failed_type_name);
525 THROW_MSG_(vmSymbols::java_lang_LinkageError(), buf, false);
526 }
527 }
528 }
529
530 put_method_at(target_method(), i);
531 overrides = true;
532 if (!is_default) {
533 target_method()->set_vtable_index(i);
534 } else {
535 if (def_vtable_indices != NULL) {
536 if (is_preinitialized_vtable()) {
537 // At runtime initialize_vtable is rerun as part of link_class_impl()
538 // for a shared class loaded by the non-boot loader.
539 // The dumptime vtable index should be the same as the runtime index.
540 assert(def_vtable_indices->at(default_index) == i,
541 "dump time vtable index is different from runtime index");
542 } else {
543 def_vtable_indices->at_put(default_index, i);
544 }
545 }
546 assert(super_method->is_default_method() || super_method->is_overpass()
547 || super_method->is_abstract(), "default override error");
548 }
549 } else {
550 overrides = false;
551 }
552 log_vtables(i, overrides, target_method, target_klass, super_method, THREAD);
553 }
554 }
555 return allocate_new;
556 }
557
558 void klassVtable::put_method_at(Method* m, int index) {
559 if (is_preinitialized_vtable()) {
560 // At runtime initialize_vtable is rerun as part of link_class_impl()
561 // for shared class loaded by the non-boot loader to obtain the loader
562 // constraints based on the runtime classloaders' context. The dumptime
563 // method at the vtable index should be the same as the runtime method.
564 assert(table()[index].method() == m,
565 "archived method is different from the runtime method");
566 } else {
567 if (log_develop_is_enabled(Trace, vtables)) {
568 ResourceMark rm;
569 LogTarget(Trace, vtables) lt;
570 LogStream ls(lt);
571 const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>";
572 ls.print("adding %s at index %d, flags: ", sig, index);
573 if (m != NULL) {
574 m->print_linkage_flags(&ls);
575 }
576 ls.cr();
577 }
578 table()[index].set(m);
579 }
580 }
581
582 // Find out if a method "m" with superclass "super", loader "classloader" and
583 // name "classname" needs a new vtable entry. Let P be a class package defined
584 // by "classloader" and "classname".
585 // NOTE: The logic used here is very similar to the one used for computing
586 // the vtables indices for a method. We cannot directly use that function because,
587 // we allocate the InstanceKlass at load time, and that requires that the
588 // superclass has been loaded.
589 // However, the vtable entries are filled in at link time, and therefore
590 // the superclass' vtable may not yet have been filled in.
591 bool klassVtable::needs_new_vtable_entry(const methodHandle& target_method,
592 const Klass* super,
593 Handle classloader,
594 Symbol* classname,
595 AccessFlags class_flags,
596 u2 major_version,
597 TRAPS) {
598 if (class_flags.is_interface()) {
599 // Interfaces do not use vtables, except for java.lang.Object methods,
600 // so there is no point to assigning
601 // a vtable index to any of their local methods. If we refrain from doing this,
602 // we can use Method::_vtable_index to hold the itable index
603 return false;
604 }
605
606 if (target_method->is_final_method(class_flags) ||
607 // a final method never needs a new entry; final methods can be statically
608 // resolved and they have to be present in the vtable only if they override
609 // a super's method, in which case they re-use its entry
610 (target_method()->is_static()) ||
611 // static methods don't need to be in vtable
612 (target_method()->name() == vmSymbols::object_initializer_name())
613 // <init> is never called dynamically-bound
614 ) {
615 return false;
616 }
617
618 // Concrete interface methods do not need new entries, they override
619 // abstract method entries using default inheritance rules
620 if (target_method()->method_holder() != NULL &&
621 target_method()->method_holder()->is_interface() &&
622 !target_method()->is_abstract()) {
623 assert(target_method()->is_default_method() || target_method()->is_private(),
624 "unexpected interface method type");
625 return false;
626 }
627
628 // we need a new entry if there is no superclass
629 if (super == NULL) {
630 return true;
631 }
632
633 // private methods in classes always have a new entry in the vtable.
634 // Specification interpretation since classic has private methods not overriding.
635 if (target_method()->is_private()) {
636 return true;
637 }
638
639 // Package private methods always need a new entry to root their own
640 // overriding. This allows transitive overriding to work.
641 if (target_method()->is_package_private()) {
642 return true;
643 }
644
645 // search through the super class hierarchy to see if we need
646 // a new entry
647 ResourceMark rm;
648 Symbol* name = target_method()->name();
649 Symbol* signature = target_method()->signature();
650 const Klass* k = super;
651 Method* super_method = NULL;
652 InstanceKlass *holder = NULL;
653 Method* recheck_method = NULL;
654 while (k != NULL) {
655 // lookup through the hierarchy for a method with matching name and sign.
656 super_method = InstanceKlass::cast(k)->lookup_method(name, signature);
657 if (super_method == NULL) {
658 break; // we still have to search for a matching miranda method
659 }
660 // get the class holding the matching method
661 // make sure you use that class for is_override
662 InstanceKlass* superk = super_method->method_holder();
663 // we want only instance method matches
664 // pretend private methods are not in the super vtable
665 // since we do override around them: e.g. a.m pub/b.m private/c.m pub,
666 // ignore private, c.m pub does override a.m pub
667 // For classes that were not javac'd together, we also do transitive overriding around
668 // methods that have less accessibility
669 if ((!super_method->is_static()) &&
670 (!super_method->is_private())) {
671 if (superk->is_override(super_method, classloader, classname, THREAD)) {
672 return false;
673 // else keep looking for transitive overrides
674 }
675 }
676
677 // Start with lookup result and continue to search up, for versions supporting transitive override
678 if (major_version >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) {
679 k = superk->super(); // haven't found an override match yet; continue to look
680 } else {
681 break;
682 }
683 }
684
685 // if the target method is public or protected it may have a matching
686 // miranda method in the super, whose entry it should re-use.
687 // Actually, to handle cases that javac would not generate, we need
688 // this check for all access permissions.
689 const InstanceKlass *sk = InstanceKlass::cast(super);
690 if (sk->has_miranda_methods()) {
691 if (sk->lookup_method_in_all_interfaces(name, signature, Klass::find_defaults) != NULL) {
692 return false; // found a matching miranda; we do not need a new entry
693 }
694 }
695 return true; // found no match; we need a new entry
696 }
697
698 // Support for miranda methods
699
700 // get the vtable index of a miranda method with matching "name" and "signature"
701 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) {
702 // search from the bottom, might be faster
703 for (int i = (length() - 1); i >= 0; i--) {
704 Method* m = table()[i].method();
705 if (is_miranda_entry_at(i) &&
706 m->name() == name && m->signature() == signature) {
707 return i;
708 }
709 }
710 return Method::invalid_vtable_index;
711 }
712
713 // check if an entry at an index is miranda
714 // requires that method m at entry be declared ("held") by an interface.
715 bool klassVtable::is_miranda_entry_at(int i) {
716 Method* m = method_at(i);
717 Klass* method_holder = m->method_holder();
718 InstanceKlass *mhk = InstanceKlass::cast(method_holder);
719
720 // miranda methods are public abstract instance interface methods in a class's vtable
721 if (mhk->is_interface()) {
722 assert(m->is_public(), "should be public");
723 assert(ik()->implements_interface(method_holder) , "this class should implement the interface");
724 if (is_miranda(m, ik()->methods(), ik()->default_methods(), ik()->super(), klass()->is_interface())) {
725 return true;
726 }
727 }
728 return false;
729 }
730
731 // Check if a method is a miranda method, given a class's methods array,
732 // its default_method table and its super class.
733 // "Miranda" means an abstract non-private method that would not be
734 // overridden for the local class.
735 // A "miranda" method should only include non-private interface
736 // instance methods, i.e. not private methods, not static methods,
737 // not default methods (concrete interface methods), not overpass methods.
738 // If a given class already has a local (including overpass) method, a
739 // default method, or any of its superclasses has the same which would have
740 // overridden an abstract method, then this is not a miranda method.
741 //
742 // Miranda methods are checked multiple times.
743 // Pass 1: during class load/class file parsing: before vtable size calculation:
744 // include superinterface abstract and default methods (non-private instance).
745 // We include potential default methods to give them space in the vtable.
746 // During the first run, the current instanceKlass has not yet been
747 // created, the superclasses and superinterfaces do have instanceKlasses
748 // but may not have vtables, the default_methods list is empty, no overpasses.
749 // Default method generation uses the all_mirandas array as the starter set for
750 // maximally-specific default method calculation. So, for both classes and
751 // interfaces, it is necessary that the first pass will find all non-private
752 // interface instance methods, whether or not they are concrete.
753 //
754 // Pass 2: recalculated during vtable initialization: only include abstract methods.
755 // The goal of pass 2 is to walk through the superinterfaces to see if any of
756 // the superinterface methods (which were all abstract pre-default methods)
757 // need to be added to the vtable.
758 // With the addition of default methods, we have three new challenges:
759 // overpasses, static interface methods and private interface methods.
760 // Static and private interface methods do not get added to the vtable and
761 // are not seen by the method resolution process, so we skip those.
762 // Overpass methods are already in the vtable, so vtable lookup will
763 // find them and we don't need to add a miranda method to the end of
764 // the vtable. So we look for overpass methods and if they are found we
765 // return false. Note that we inherit our superclasses vtable, so
766 // the superclass' search also needs to use find_overpass so that if
767 // one is found we return false.
768 // False means - we don't need a miranda method added to the vtable.
769 //
770 // During the second run, default_methods is set up, so concrete methods from
771 // superinterfaces with matching names/signatures to default_methods are already
772 // in the default_methods list and do not need to be appended to the vtable
773 // as mirandas. Abstract methods may already have been handled via
774 // overpasses - either local or superclass overpasses, which may be
775 // in the vtable already.
776 //
777 // Pass 3: They are also checked by link resolution and selection,
778 // for invocation on a method (not interface method) reference that
779 // resolves to a method with an interface as its method_holder.
780 // Used as part of walking from the bottom of the vtable to find
781 // the vtable index for the miranda method.
782 //
783 // Part of the Miranda Rights in the US mean that if you do not have
784 // an attorney one will be appointed for you.
785 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods,
786 Array<Method*>* default_methods, const Klass* super,
787 bool is_interface) {
788 if (m->is_static() || m->is_private() || m->is_overpass()) {
789 return false;
790 }
791 Symbol* name = m->name();
792 Symbol* signature = m->signature();
793
794 // First look in local methods to see if already covered
795 if (InstanceKlass::find_local_method(class_methods, name, signature,
796 Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL)
797 {
798 return false;
799 }
800
801 // Check local default methods
802 if ((default_methods != NULL) &&
803 (InstanceKlass::find_method(default_methods, name, signature) != NULL))
804 {
805 return false;
806 }
807
808 // Iterate on all superclasses, which should be InstanceKlasses.
809 // Note that we explicitly look for overpasses at each level.
810 // Overpasses may or may not exist for supers for pass 1,
811 // they should have been created for pass 2 and later.
812
813 for (const Klass* cursuper = super; cursuper != NULL; cursuper = cursuper->super())
814 {
815 Method* found_mth = InstanceKlass::cast(cursuper)->find_local_method(name, signature,
816 Klass::find_overpass, Klass::skip_static, Klass::skip_private);
817 // Ignore non-public methods in java.lang.Object if klass is an interface.
818 if (found_mth != NULL && (!is_interface ||
819 !SystemDictionary::is_nonpublic_Object_method(found_mth))) {
820 return false;
821 }
822 }
823
824 return true;
825 }
826
827 // Scans current_interface_methods for miranda methods that do not
828 // already appear in new_mirandas, or default methods, and are also not defined-and-non-private
829 // in super (superclass). These mirandas are added to all_mirandas if it is
830 // not null; in addition, those that are not duplicates of miranda methods
831 // inherited by super from its interfaces are added to new_mirandas.
832 // Thus, new_mirandas will be the set of mirandas that this class introduces,
833 // all_mirandas will be the set of all mirandas applicable to this class
834 // including all defined in superclasses.
835 void klassVtable::add_new_mirandas_to_lists(
836 GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas,
837 Array<Method*>* current_interface_methods, Array<Method*>* class_methods,
838 Array<Method*>* default_methods, const Klass* super, bool is_interface) {
839
840 // iterate thru the current interface's method to see if it a miranda
841 int num_methods = current_interface_methods->length();
842 for (int i = 0; i < num_methods; i++) {
843 Method* im = current_interface_methods->at(i);
844 bool is_duplicate = false;
845 int num_of_current_mirandas = new_mirandas->length();
846 // check for duplicate mirandas in different interfaces we implement
847 for (int j = 0; j < num_of_current_mirandas; j++) {
848 Method* miranda = new_mirandas->at(j);
849 if ((im->name() == miranda->name()) &&
850 (im->signature() == miranda->signature())) {
851 is_duplicate = true;
852 break;
853 }
854 }
855
856 if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable
857 if (is_miranda(im, class_methods, default_methods, super, is_interface)) { // is it a miranda at all?
858 const InstanceKlass *sk = InstanceKlass::cast(super);
859 // check if it is a duplicate of a super's miranda
860 if (sk->lookup_method_in_all_interfaces(im->name(), im->signature(), Klass::find_defaults) == NULL) {
861 new_mirandas->append(im);
862 }
863 if (all_mirandas != NULL) {
864 all_mirandas->append(im);
865 }
866 }
867 }
868 }
869 }
870
871 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas,
872 GrowableArray<Method*>* all_mirandas,
873 const Klass* super,
874 Array<Method*>* class_methods,
875 Array<Method*>* default_methods,
876 Array<Klass*>* local_interfaces,
877 bool is_interface) {
878 assert((new_mirandas->length() == 0) , "current mirandas must be 0");
879
880 // iterate thru the local interfaces looking for a miranda
881 int num_local_ifs = local_interfaces->length();
882 for (int i = 0; i < num_local_ifs; i++) {
883 InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i));
884 add_new_mirandas_to_lists(new_mirandas, all_mirandas,
885 ik->methods(), class_methods,
886 default_methods, super, is_interface);
887 // iterate thru each local's super interfaces
888 Array<Klass*>* super_ifs = ik->transitive_interfaces();
889 int num_super_ifs = super_ifs->length();
890 for (int j = 0; j < num_super_ifs; j++) {
891 InstanceKlass *sik = InstanceKlass::cast(super_ifs->at(j));
892 add_new_mirandas_to_lists(new_mirandas, all_mirandas,
893 sik->methods(), class_methods,
894 default_methods, super, is_interface);
895 }
896 }
897 }
898
899 // Discover miranda methods ("miranda" = "interface abstract, no binding"),
900 // and append them into the vtable starting at index initialized,
901 // return the new value of initialized.
902 // Miranda methods use vtable entries, but do not get assigned a vtable_index
903 // The vtable_index is discovered by searching from the end of the vtable
904 int klassVtable::fill_in_mirandas(int initialized) {
905 GrowableArray<Method*> mirandas(20);
906 get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(),
907 ik()->default_methods(), ik()->local_interfaces(),
908 klass()->is_interface());
909 for (int i = 0; i < mirandas.length(); i++) {
910 if (log_develop_is_enabled(Trace, vtables)) {
911 Method* meth = mirandas.at(i);
912 ResourceMark rm(Thread::current());
913 LogTarget(Trace, vtables) lt;
914 LogStream ls(lt);
915 if (meth != NULL) {
916 char* sig = meth->name_and_sig_as_C_string();
917 ls.print("fill in mirandas with %s index %d, flags: ",
918 sig, initialized);
919 meth->print_linkage_flags(&ls);
920 ls.cr();
921 }
922 }
923 put_method_at(mirandas.at(i), initialized);
924 ++initialized;
925 }
926 return initialized;
927 }
928
929 // Copy this class's vtable to the vtable beginning at start.
930 // Used to copy superclass vtable to prefix of subclass's vtable.
931 void klassVtable::copy_vtable_to(vtableEntry* start) {
932 Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size());
933 }
934
935 #if INCLUDE_JVMTI
936 bool klassVtable::adjust_default_method(int vtable_index, Method* old_method, Method* new_method) {
937 // If old_method is default, find this vtable index in default_vtable_indices
938 // and replace that method in the _default_methods list
939 bool updated = false;
940
941 Array<Method*>* default_methods = ik()->default_methods();
942 if (default_methods != NULL) {
943 int len = default_methods->length();
944 for (int idx = 0; idx < len; idx++) {
945 if (vtable_index == ik()->default_vtable_indices()->at(idx)) {
946 if (default_methods->at(idx) == old_method) {
947 default_methods->at_put(idx, new_method);
948 updated = true;
949 }
950 break;
951 }
952 }
953 }
954 return updated;
955 }
956
957 // search the vtable for uses of either obsolete or EMCP methods
958 void klassVtable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) {
959 int prn_enabled = 0;
960 for (int index = 0; index < length(); index++) {
961 Method* old_method = unchecked_method_at(index);
962 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) {
963 continue; // skip uninteresting entries
964 }
965 assert(!old_method->is_deleted(), "vtable methods may not be deleted");
966
967 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum());
968
969 assert(new_method != NULL, "method_with_idnum() should not be NULL");
970 assert(old_method != new_method, "sanity check");
971
972 put_method_at(new_method, index);
973 // For default methods, need to update the _default_methods array
974 // which can only have one method entry for a given signature
975 bool updated_default = false;
976 if (old_method->is_default_method()) {
977 updated_default = adjust_default_method(index, old_method, new_method);
978 }
979
980 if (log_is_enabled(Info, redefine, class, update)) {
981 ResourceMark rm;
982 if (!(*trace_name_printed)) {
983 log_info(redefine, class, update)
984 ("adjust: klassname=%s for methods from name=%s",
985 _klass->external_name(), old_method->method_holder()->external_name());
986 *trace_name_printed = true;
987 }
988 log_debug(redefine, class, update, vtables)
989 ("vtable method update: %s(%s), updated default = %s",
990 new_method->name()->as_C_string(), new_method->signature()->as_C_string(), updated_default ? "true" : "false");
991 }
992 }
993 }
994
995 // a vtable should never contain old or obsolete methods
996 bool klassVtable::check_no_old_or_obsolete_entries() {
997 for (int i = 0; i < length(); i++) {
998 Method* m = unchecked_method_at(i);
999 if (m != NULL &&
1000 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
1001 return false;
1002 }
1003 }
1004 return true;
1005 }
1006
1007 void klassVtable::dump_vtable() {
1008 tty->print_cr("vtable dump --");
1009 for (int i = 0; i < length(); i++) {
1010 Method* m = unchecked_method_at(i);
1011 if (m != NULL) {
1012 tty->print(" (%5d) ", i);
1013 m->access_flags().print_on(tty);
1014 if (m->is_default_method()) {
1015 tty->print("default ");
1016 }
1017 if (m->is_overpass()) {
1018 tty->print("overpass");
1019 }
1020 tty->print(" -- ");
1021 m->print_name(tty);
1022 tty->cr();
1023 }
1024 }
1025 }
1026 #endif // INCLUDE_JVMTI
1027
1028 // CDS/RedefineClasses support - clear vtables so they can be reinitialized
1029 void klassVtable::clear_vtable() {
1030 for (int i = 0; i < _length; i++) table()[i].clear();
1031 }
1032
1033 bool klassVtable::is_initialized() {
1034 return _length == 0 || table()[0].method() != NULL;
1035 }
1036
1037 //-----------------------------------------------------------------------------------------
1038 // Itable code
1039
1040 // Initialize a itableMethodEntry
1041 void itableMethodEntry::initialize(Method* m) {
1042 if (m == NULL) return;
1043
1044 #ifdef ASSERT
1045 if (MetaspaceShared::is_in_shared_metaspace((void*)&_method) &&
1046 !MetaspaceShared::remapped_readwrite()) {
1047 // At runtime initialize_itable is rerun as part of link_class_impl()
1048 // for a shared class loaded by the non-boot loader.
1049 // The dumptime itable method entry should be the same as the runtime entry.
1050 assert(_method == m, "sanity");
1051 }
1052 #endif
1053 _method = m;
1054 }
1055
1056 klassItable::klassItable(InstanceKlass* klass) {
1057 _klass = klass;
1058
1059 if (klass->itable_length() > 0) {
1060 itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable();
1061 if (offset_entry != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized
1062 // First offset entry points to the first method_entry
1063 intptr_t* method_entry = (intptr_t *)(((address)klass) + offset_entry->offset());
1064 intptr_t* end = klass->end_of_itable();
1065
1066 _table_offset = (intptr_t*)offset_entry - (intptr_t*)klass;
1067 _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size();
1068 _size_method_table = (end - method_entry) / itableMethodEntry::size();
1069 assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation");
1070 return;
1071 }
1072 }
1073
1074 // The length of the itable was either zero, or it has not yet been initialized.
1075 _table_offset = 0;
1076 _size_offset_table = 0;
1077 _size_method_table = 0;
1078 }
1079
1080 static int initialize_count = 0;
1081
1082 // Initialization
1083 void klassItable::initialize_itable(bool checkconstraints, TRAPS) {
1084 if (_klass->is_interface()) {
1085 // This needs to go after vtable indices are assigned but
1086 // before implementors need to know the number of itable indices.
1087 assign_itable_indices_for_interface(_klass);
1088 }
1089
1090 // Cannot be setup doing bootstrapping, interfaces don't have
1091 // itables, and klass with only ones entry have empty itables
1092 if (Universe::is_bootstrapping() ||
1093 _klass->is_interface() ||
1094 _klass->itable_length() == itableOffsetEntry::size()) return;
1095
1096 // There's alway an extra itable entry so we can null-terminate it.
1097 guarantee(size_offset_table() >= 1, "too small");
1098 int num_interfaces = size_offset_table() - 1;
1099 if (num_interfaces > 0) {
1100 log_develop_debug(itables)("%3d: Initializing itables for %s", ++initialize_count,
1101 _klass->name()->as_C_string());
1102
1103
1104 // Iterate through all interfaces
1105 int i;
1106 for(i = 0; i < num_interfaces; i++) {
1107 itableOffsetEntry* ioe = offset_entry(i);
1108 HandleMark hm(THREAD);
1109 Klass* interf = ioe->interface_klass();
1110 assert(interf != NULL && ioe->offset() != 0, "bad offset entry in itable");
1111 initialize_itable_for_interface(ioe->offset(), interf, checkconstraints, CHECK);
1112 }
1113
1114 }
1115 // Check that the last entry is empty
1116 itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1);
1117 guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing");
1118 }
1119
1120
1121 inline bool interface_method_needs_itable_index(Method* m) {
1122 if (m->is_static()) return false; // e.g., Stream.empty
1123 if (m->is_initializer()) return false; // <init> or <clinit>
1124 if (m->is_private()) return false; // requires invokeSpecial
1125 // If an interface redeclares a method from java.lang.Object,
1126 // it should already have a vtable index, don't touch it.
1127 // e.g., CharSequence.toString (from initialize_vtable)
1128 // if (m->has_vtable_index()) return false; // NO!
1129 return true;
1130 }
1131
1132 int klassItable::assign_itable_indices_for_interface(Klass* klass) {
1133 // an interface does not have an itable, but its methods need to be numbered
1134 log_develop_debug(itables)("%3d: Initializing itable indices for interface %s",
1135 ++initialize_count, klass->name()->as_C_string());
1136 Array<Method*>* methods = InstanceKlass::cast(klass)->methods();
1137 int nof_methods = methods->length();
1138 int ime_num = 0;
1139 for (int i = 0; i < nof_methods; i++) {
1140 Method* m = methods->at(i);
1141 if (interface_method_needs_itable_index(m)) {
1142 assert(!m->is_final_method(), "no final interface methods");
1143 // If m is already assigned a vtable index, do not disturb it.
1144 if (log_develop_is_enabled(Trace, itables)) {
1145 ResourceMark rm;
1146 LogTarget(Trace, itables) lt;
1147 LogStream ls(lt);
1148 assert(m != NULL, "methods can never be null");
1149 const char* sig = m->name_and_sig_as_C_string();
1150 if (m->has_vtable_index()) {
1151 ls.print("vtable index %d for method: %s, flags: ", m->vtable_index(), sig);
1152 } else {
1153 ls.print("itable index %d for method: %s, flags: ", ime_num, sig);
1154 }
1155 m->print_linkage_flags(&ls);
1156 ls.cr();
1157 }
1158 if (!m->has_vtable_index()) {
1159 // A shared method could have an initialized itable_index that
1160 // is < 0.
1161 assert(m->vtable_index() == Method::pending_itable_index ||
1162 m->is_shared(),
1163 "set by initialize_vtable");
1164 m->set_itable_index(ime_num);
1165 // Progress to next itable entry
1166 ime_num++;
1167 }
1168 }
1169 }
1170 assert(ime_num == method_count_for_interface(klass), "proper sizing");
1171 return ime_num;
1172 }
1173
1174 int klassItable::method_count_for_interface(Klass* interf) {
1175 assert(interf->is_instance_klass(), "must be");
1176 assert(interf->is_interface(), "must be");
1177 Array<Method*>* methods = InstanceKlass::cast(interf)->methods();
1178 int nof_methods = methods->length();
1179 int length = 0;
1180 while (nof_methods > 0) {
1181 Method* m = methods->at(nof_methods-1);
1182 if (m->has_itable_index()) {
1183 length = m->itable_index() + 1;
1184 break;
1185 }
1186 nof_methods -= 1;
1187 }
1188 #ifdef ASSERT
1189 int nof_methods_copy = nof_methods;
1190 while (nof_methods_copy > 0) {
1191 Method* mm = methods->at(--nof_methods_copy);
1192 assert(!mm->has_itable_index() || mm->itable_index() < length, "");
1193 }
1194 #endif //ASSERT
1195 // return the rightmost itable index, plus one; or 0 if no methods have
1196 // itable indices
1197 return length;
1198 }
1199
1200
1201 void klassItable::initialize_itable_for_interface(int method_table_offset, Klass* interf, bool checkconstraints, TRAPS) {
1202 Array<Method*>* methods = InstanceKlass::cast(interf)->methods();
1203 int nof_methods = methods->length();
1204 HandleMark hm;
1205 Handle interface_loader (THREAD, InstanceKlass::cast(interf)->class_loader());
1206
1207 int ime_count = method_count_for_interface(interf);
1208 for (int i = 0; i < nof_methods; i++) {
1209 Method* m = methods->at(i);
1210 methodHandle target;
1211 if (m->has_itable_index()) {
1212 // This search must match the runtime resolution, i.e. selection search for invokeinterface
1213 // to correctly enforce loader constraints for interface method inheritance
1214 target = LinkResolver::lookup_instance_method_in_klasses(_klass, m->name(), m->signature(), CHECK);
1215 }
1216 if (target == NULL || !target->is_public() || target->is_abstract() || target->is_overpass()) {
1217 assert(target == NULL || !target->is_overpass() || target->is_public(),
1218 "Non-public overpass method!");
1219 // Entry does not resolve. Leave it empty for AbstractMethodError or other error.
1220 if (!(target == NULL) && !target->is_public()) {
1221 // Stuff an IllegalAccessError throwing method in there instead.
1222 itableOffsetEntry::method_entry(_klass, method_table_offset)[m->itable_index()].
1223 initialize(Universe::throw_illegal_access_error());
1224 }
1225 } else {
1226 // Entry did resolve, check loader constraints before initializing
1227 // if checkconstraints requested
1228 if (checkconstraints) {
1229 Handle method_holder_loader (THREAD, target->method_holder()->class_loader());
1230 if (method_holder_loader() != interface_loader()) {
1231 ResourceMark rm(THREAD);
1232 Symbol* failed_type_symbol =
1233 SystemDictionary::check_signature_loaders(m->signature(),
1234 method_holder_loader,
1235 interface_loader,
1236 true, CHECK);
1237 if (failed_type_symbol != NULL) {
1238 const char* msg = "loader constraint violation in interface itable"
1239 " initialization for class %s: when selecting method \"%s\" the"
1240 " class loader (instance of %s) for super interface %s, and the class"
1241 " loader (instance of %s) of the selected method's type, %s have"
1242 " different Class objects for the type %s used in the signature";
1243 char* current = _klass->name()->as_C_string();
1244 char* sig = m->name_and_sig_as_C_string();
1245 const char* loader1 = SystemDictionary::loader_name(interface_loader());
1246 char* iface = InstanceKlass::cast(interf)->name()->as_C_string();
1247 const char* loader2 = SystemDictionary::loader_name(method_holder_loader());
1248 char* mclass = target()->method_holder()->name()->as_C_string();
1249 char* failed_type_name = failed_type_symbol->as_C_string();
1250 size_t buflen = strlen(msg) + strlen(current) + strlen(sig) +
1251 strlen(loader1) + strlen(iface) + strlen(loader2) + strlen(mclass) +
1252 strlen(failed_type_name);
1253 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
1254 jio_snprintf(buf, buflen, msg, current, sig, loader1, iface,
1255 loader2, mclass, failed_type_name);
1256 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
1257 }
1258 }
1259 }
1260
1261 // ime may have moved during GC so recalculate address
1262 int ime_num = m->itable_index();
1263 assert(ime_num < ime_count, "oob");
1264 itableOffsetEntry::method_entry(_klass, method_table_offset)[ime_num].initialize(target());
1265 if (log_develop_is_enabled(Trace, itables)) {
1266 ResourceMark rm(THREAD);
1267 if (target() != NULL) {
1268 LogTarget(Trace, itables) lt;
1269 LogStream ls(lt);
1270 char* sig = target()->name_and_sig_as_C_string();
1271 ls.print("interface: %s, ime_num: %d, target: %s, method_holder: %s ",
1272 interf->internal_name(), ime_num, sig,
1273 target()->method_holder()->internal_name());
1274 ls.print("target_method flags: ");
1275 target()->print_linkage_flags(&ls);
1276 ls.cr();
1277 }
1278 }
1279 }
1280 }
1281 }
1282
1283 #if INCLUDE_JVMTI
1284 // search the itable for uses of either obsolete or EMCP methods
1285 void klassItable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) {
1286
1287 itableMethodEntry* ime = method_entry(0);
1288 for (int i = 0; i < _size_method_table; i++, ime++) {
1289 Method* old_method = ime->method();
1290 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) {
1291 continue; // skip uninteresting entries
1292 }
1293 assert(!old_method->is_deleted(), "itable methods may not be deleted");
1294
1295 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum());
1296
1297 assert(new_method != NULL, "method_with_idnum() should not be NULL");
1298 assert(old_method != new_method, "sanity check");
1299
1300 ime->initialize(new_method);
1301
1302 if (log_is_enabled(Info, redefine, class, update)) {
1303 ResourceMark rm;
1304 if (!(*trace_name_printed)) {
1305 log_info(redefine, class, update)("adjust: name=%s", old_method->method_holder()->external_name());
1306 *trace_name_printed = true;
1307 }
1308 log_trace(redefine, class, update, itables)
1309 ("itable method update: %s(%s)", new_method->name()->as_C_string(), new_method->signature()->as_C_string());
1310 }
1311 }
1312 }
1313
1314 // an itable should never contain old or obsolete methods
1315 bool klassItable::check_no_old_or_obsolete_entries() {
1316 itableMethodEntry* ime = method_entry(0);
1317 for (int i = 0; i < _size_method_table; i++) {
1318 Method* m = ime->method();
1319 if (m != NULL &&
1320 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
1321 return false;
1322 }
1323 ime++;
1324 }
1325 return true;
1326 }
1327
1328 void klassItable::dump_itable() {
1329 itableMethodEntry* ime = method_entry(0);
1330 tty->print_cr("itable dump --");
1331 for (int i = 0; i < _size_method_table; i++) {
1332 Method* m = ime->method();
1333 if (m != NULL) {
1334 tty->print(" (%5d) ", i);
1335 m->access_flags().print_on(tty);
1336 if (m->is_default_method()) {
1337 tty->print("default ");
1338 }
1339 tty->print(" -- ");
1340 m->print_name(tty);
1341 tty->cr();
1342 }
1343 ime++;
1344 }
1345 }
1346 #endif // INCLUDE_JVMTI
1347
1348 // Setup
1349 class InterfaceVisiterClosure : public StackObj {
1350 public:
1351 virtual void doit(Klass* intf, int method_count) = 0;
1352 };
1353
1354 int count_interface_methods_needing_itable_index(Array<Method*>* methods) {
1355 int method_count = 0;
1356 if (methods->length() > 0) {
1357 for (int i = methods->length(); --i >= 0; ) {
1358 if (interface_method_needs_itable_index(methods->at(i))) {
1359 method_count++;
1360 }
1361 }
1362 }
1363 return method_count;
1364 }
1365
1366 // Visit all interfaces with at least one itable method
1367 void visit_all_interfaces(Array<Klass*>* transitive_intf, InterfaceVisiterClosure *blk) {
1368 // Handle array argument
1369 for(int i = 0; i < transitive_intf->length(); i++) {
1370 Klass* intf = transitive_intf->at(i);
1371 assert(intf->is_interface(), "sanity check");
1372
1373 // Find no. of itable methods
1374 int method_count = 0;
1375 // method_count = klassItable::method_count_for_interface(intf);
1376 Array<Method*>* methods = InstanceKlass::cast(intf)->methods();
1377 if (methods->length() > 0) {
1378 for (int i = methods->length(); --i >= 0; ) {
1379 if (interface_method_needs_itable_index(methods->at(i))) {
1380 method_count++;
1381 }
1382 }
1383 }
1384
1385 // Visit all interfaces which either have any methods or can participate in receiver type check.
1386 // We do not bother to count methods in transitive interfaces, although that would allow us to skip
1387 // this step in the rare case of a zero-method interface extending another zero-method interface.
1388 if (method_count > 0 || InstanceKlass::cast(intf)->transitive_interfaces()->length() > 0) {
1389 blk->doit(intf, method_count);
1390 }
1391 }
1392 }
1393
1394 class CountInterfacesClosure : public InterfaceVisiterClosure {
1395 private:
1396 int _nof_methods;
1397 int _nof_interfaces;
1398 public:
1399 CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; }
1400
1401 int nof_methods() const { return _nof_methods; }
1402 int nof_interfaces() const { return _nof_interfaces; }
1403
1404 void doit(Klass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; }
1405 };
1406
1407 class SetupItableClosure : public InterfaceVisiterClosure {
1408 private:
1409 itableOffsetEntry* _offset_entry;
1410 itableMethodEntry* _method_entry;
1411 address _klass_begin;
1412 public:
1413 SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) {
1414 _klass_begin = klass_begin;
1415 _offset_entry = offset_entry;
1416 _method_entry = method_entry;
1417 }
1418
1419 itableMethodEntry* method_entry() const { return _method_entry; }
1420
1421 void doit(Klass* intf, int method_count) {
1422 int offset = ((address)_method_entry) - _klass_begin;
1423 _offset_entry->initialize(intf, offset);
1424 _offset_entry++;
1425 _method_entry += method_count;
1426 }
1427 };
1428
1429 int klassItable::compute_itable_size(Array<Klass*>* transitive_interfaces) {
1430 // Count no of interfaces and total number of interface methods
1431 CountInterfacesClosure cic;
1432 visit_all_interfaces(transitive_interfaces, &cic);
1433
1434 // There's always an extra itable entry so we can null-terminate it.
1435 int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods());
1436
1437 // Statistics
1438 update_stats(itable_size * wordSize);
1439
1440 return itable_size;
1441 }
1442
1443
1444 // Fill out offset table and interface klasses into the itable space
1445 void klassItable::setup_itable_offset_table(InstanceKlass* klass) {
1446 if (klass->itable_length() == 0) return;
1447 assert(!klass->is_interface(), "Should have zero length itable");
1448
1449 // Count no of interfaces and total number of interface methods
1450 CountInterfacesClosure cic;
1451 visit_all_interfaces(klass->transitive_interfaces(), &cic);
1452 int nof_methods = cic.nof_methods();
1453 int nof_interfaces = cic.nof_interfaces();
1454
1455 // Add one extra entry so we can null-terminate the table
1456 nof_interfaces++;
1457
1458 assert(compute_itable_size(klass->transitive_interfaces()) ==
1459 calc_itable_size(nof_interfaces, nof_methods),
1460 "mismatch calculation of itable size");
1461
1462 // Fill-out offset table
1463 itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable();
1464 itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces);
1465 intptr_t* end = klass->end_of_itable();
1466 assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)");
1467 assert((oop*)(end) == (oop*)(ime + nof_methods), "wrong offset calculation (2)");
1468
1469 // Visit all interfaces and initialize itable offset table
1470 SetupItableClosure sic((address)klass, ioe, ime);
1471 visit_all_interfaces(klass->transitive_interfaces(), &sic);
1472
1473 #ifdef ASSERT
1474 ime = sic.method_entry();
1475 oop* v = (oop*) klass->end_of_itable();
1476 assert( (oop*)(ime) == v, "wrong offset calculation (2)");
1477 #endif
1478 }
1479
1480
1481 // inverse to itable_index
1482 Method* klassItable::method_for_itable_index(Klass* intf, int itable_index) {
1483 assert(InstanceKlass::cast(intf)->is_interface(), "sanity check");
1484 assert(intf->verify_itable_index(itable_index), "");
1485 Array<Method*>* methods = InstanceKlass::cast(intf)->methods();
1486
1487 if (itable_index < 0 || itable_index >= method_count_for_interface(intf))
1488 return NULL; // help caller defend against bad indices
1489
1490 int index = itable_index;
1491 Method* m = methods->at(index);
1492 int index2 = -1;
1493 while (!m->has_itable_index() ||
1494 (index2 = m->itable_index()) != itable_index) {
1495 assert(index2 < itable_index, "monotonic");
1496 if (++index == methods->length())
1497 return NULL;
1498 m = methods->at(index);
1499 }
1500 assert(m->itable_index() == itable_index, "correct inverse");
1501
1502 return m;
1503 }
1504
1505 void klassVtable::verify(outputStream* st, bool forced) {
1506 // make sure table is initialized
1507 if (!Universe::is_fully_initialized()) return;
1508 #ifndef PRODUCT
1509 // avoid redundant verifies
1510 if (!forced && _verify_count == Universe::verify_count()) return;
1511 _verify_count = Universe::verify_count();
1512 #endif
1513 oop* end_of_obj = (oop*)_klass + _klass->size();
1514 oop* end_of_vtable = (oop *)&table()[_length];
1515 if (end_of_vtable > end_of_obj) {
1516 fatal("klass %s: klass object too short (vtable extends beyond end)",
1517 _klass->internal_name());
1518 }
1519
1520 for (int i = 0; i < _length; i++) table()[i].verify(this, st);
1521 // verify consistency with superKlass vtable
1522 Klass* super = _klass->super();
1523 if (super != NULL) {
1524 InstanceKlass* sk = InstanceKlass::cast(super);
1525 klassVtable vt = sk->vtable();
1526 for (int i = 0; i < vt.length(); i++) {
1527 verify_against(st, &vt, i);
1528 }
1529 }
1530 }
1531
1532 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) {
1533 vtableEntry* vte = &vt->table()[index];
1534 if (vte->method()->name() != table()[index].method()->name() ||
1535 vte->method()->signature() != table()[index].method()->signature()) {
1536 fatal("mismatched name/signature of vtable entries");
1537 }
1538 }
1539
1540 #ifndef PRODUCT
1541 void klassVtable::print() {
1542 ResourceMark rm;
1543 tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length());
1544 for (int i = 0; i < length(); i++) {
1545 table()[i].print();
1546 tty->cr();
1547 }
1548 }
1549 #endif
1550
1551 void vtableEntry::verify(klassVtable* vt, outputStream* st) {
1552 NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true));
1553 Klass* vtklass = vt->klass();
1554 if (vtklass->is_instance_klass() &&
1555 (InstanceKlass::cast(vtklass)->major_version() >= klassVtable::VTABLE_TRANSITIVE_OVERRIDE_VERSION)) {
1556 assert(method() != NULL, "must have set method");
1557 }
1558 if (method() != NULL) {
1559 method()->verify();
1560 // we sub_type, because it could be a miranda method
1561 if (!vtklass->is_subtype_of(method()->method_holder())) {
1562 #ifndef PRODUCT
1563 print();
1564 #endif
1565 fatal("vtableEntry " PTR_FORMAT ": method is from subclass", p2i(this));
1566 }
1567 }
1568 }
1569
1570 #ifndef PRODUCT
1571
1572 void vtableEntry::print() {
1573 ResourceMark rm;
1574 tty->print("vtableEntry %s: ", method()->name()->as_C_string());
1575 if (Verbose) {
1576 tty->print("m " PTR_FORMAT " ", p2i(method()));
1577 }
1578 }
1579
1580 class VtableStats : AllStatic {
1581 public:
1582 static int no_klasses; // # classes with vtables
1583 static int no_array_klasses; // # array classes
1584 static int no_instance_klasses; // # instanceKlasses
1585 static int sum_of_vtable_len; // total # of vtable entries
1586 static int sum_of_array_vtable_len; // total # of vtable entries in array klasses only
1587 static int fixed; // total fixed overhead in bytes
1588 static int filler; // overhead caused by filler bytes
1589 static int entries; // total bytes consumed by vtable entries
1590 static int array_entries; // total bytes consumed by array vtable entries
1591
1592 static void do_class(Klass* k) {
1593 Klass* kl = k;
1594 klassVtable vt = kl->vtable();
1595 no_klasses++;
1596 if (kl->is_instance_klass()) {
1597 no_instance_klasses++;
1598 kl->array_klasses_do(do_class);
1599 }
1600 if (kl->is_array_klass()) {
1601 no_array_klasses++;
1602 sum_of_array_vtable_len += vt.length();
1603 }
1604 sum_of_vtable_len += vt.length();
1605 }
1606
1607 static void compute() {
1608 ClassLoaderDataGraph::classes_do(do_class);
1609 fixed = no_klasses * oopSize; // vtable length
1610 // filler size is a conservative approximation
1611 filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(InstanceKlass) - sizeof(ArrayKlass) - 1);
1612 entries = sizeof(vtableEntry) * sum_of_vtable_len;
1613 array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len;
1614 }
1615 };
1616
1617 int VtableStats::no_klasses = 0;
1618 int VtableStats::no_array_klasses = 0;
1619 int VtableStats::no_instance_klasses = 0;
1620 int VtableStats::sum_of_vtable_len = 0;
1621 int VtableStats::sum_of_array_vtable_len = 0;
1622 int VtableStats::fixed = 0;
1623 int VtableStats::filler = 0;
1624 int VtableStats::entries = 0;
1625 int VtableStats::array_entries = 0;
1626
1627 void klassVtable::print_statistics() {
1628 ResourceMark rm;
1629 HandleMark hm;
1630 VtableStats::compute();
1631 tty->print_cr("vtable statistics:");
1632 tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses);
1633 int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries;
1634 tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed);
1635 tty->print_cr("%6d bytes filler overhead", VtableStats::filler);
1636 tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries);
1637 tty->print_cr("%6d bytes total", total);
1638 }
1639
1640 int klassItable::_total_classes; // Total no. of classes with itables
1641 long klassItable::_total_size; // Total no. of bytes used for itables
1642
1643 void klassItable::print_statistics() {
1644 tty->print_cr("itable statistics:");
1645 tty->print_cr("%6d classes with itables", _total_classes);
1646 tty->print_cr("%6lu K uses for itables (average by class: %ld bytes)", _total_size / K, _total_size / _total_classes);
1647 }
1648
1649 #endif // PRODUCT