1 /*
2 * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "classfile/vmSymbols.hpp"
28 #include "gc/shared/gcLocker.hpp"
29 #include "logging/log.hpp"
30 #include "memory/resourceArea.hpp"
31 #include "memory/universe.inline.hpp"
32 #include "oops/instanceKlass.hpp"
33 #include "oops/klassVtable.hpp"
34 #include "oops/method.hpp"
35 #include "oops/objArrayOop.hpp"
36 #include "oops/oop.inline.hpp"
37 #include "prims/jvmtiRedefineClassesTrace.hpp"
38 #include "runtime/arguments.hpp"
39 #include "runtime/handles.inline.hpp"
40 #include "utilities/copy.hpp"
41
42 inline InstanceKlass* klassVtable::ik() const {
43 return InstanceKlass::cast(_klass());
44 }
45
46
47 // this function computes the vtable size (including the size needed for miranda
48 // methods) and the number of miranda methods in this class.
49 // Note on Miranda methods: Let's say there is a class C that implements
50 // interface I, and none of C's superclasses implements I.
51 // Let's say there is an abstract method m in I that neither C
52 // nor any of its super classes implement (i.e there is no method of any access,
53 // with the same name and signature as m), then m is a Miranda method which is
54 // entered as a public abstract method in C's vtable. From then on it should
55 // treated as any other public method in C for method over-ride purposes.
56 void klassVtable::compute_vtable_size_and_num_mirandas(
57 int* vtable_length_ret, int* num_new_mirandas,
58 GrowableArray<Method*>* all_mirandas, const Klass* super,
59 Array<Method*>* methods, AccessFlags class_flags,
60 Handle classloader, Symbol* classname, Array<Klass*>* local_interfaces,
61 TRAPS) {
62 NoSafepointVerifier nsv;
63
64 // set up default result values
65 int vtable_length = 0;
66
67 // start off with super's vtable length
68 vtable_length = super == NULL ? 0 : super->vtable_length();
69
70 // go thru each method in the methods table to see if it needs a new entry
71 int len = methods->length();
72 for (int i = 0; i < len; i++) {
73 assert(methods->at(i)->is_method(), "must be a Method*");
74 methodHandle mh(THREAD, methods->at(i));
75
76 if (needs_new_vtable_entry(mh, super, classloader, classname, class_flags, THREAD)) {
77 vtable_length += vtableEntry::size(); // we need a new entry
78 }
79 }
80
81 GrowableArray<Method*> new_mirandas(20);
82 // compute the number of mirandas methods that must be added to the end
83 get_mirandas(&new_mirandas, all_mirandas, super, methods, NULL, local_interfaces);
84 *num_new_mirandas = new_mirandas.length();
85
86 // Interfaces do not need interface methods in their vtables
87 // This includes miranda methods and during later processing, default methods
88 if (!class_flags.is_interface()) {
89 vtable_length += *num_new_mirandas * vtableEntry::size();
90 }
91
92 if (Universe::is_bootstrapping() && vtable_length == 0) {
93 // array classes don't have their superclass set correctly during
94 // bootstrapping
95 vtable_length = Universe::base_vtable_size();
96 }
97
98 if (super == NULL && vtable_length != Universe::base_vtable_size()) {
99 if (Universe::is_bootstrapping()) {
100 // Someone is attempting to override java.lang.Object incorrectly on the
101 // bootclasspath. The JVM cannot recover from this error including throwing
102 // an exception
103 vm_exit_during_initialization("Incompatible definition of java.lang.Object");
104 } else {
105 // Someone is attempting to redefine java.lang.Object incorrectly. The
106 // only way this should happen is from
107 // SystemDictionary::resolve_from_stream(), which will detect this later
108 // and throw a security exception. So don't assert here to let
109 // the exception occur.
110 vtable_length = Universe::base_vtable_size();
111 }
112 }
113 assert(vtable_length % vtableEntry::size() == 0, "bad vtable length");
114 assert(vtable_length >= Universe::base_vtable_size(), "vtable too small");
115
116 *vtable_length_ret = vtable_length;
117 }
118
119 int klassVtable::index_of(Method* m, int len) const {
120 assert(m->has_vtable_index(), "do not ask this of non-vtable methods");
121 return m->vtable_index();
122 }
123
124 // Copy super class's vtable to the first part (prefix) of this class's vtable,
125 // and return the number of entries copied. Expects that 'super' is the Java
126 // super class (arrays can have "array" super classes that must be skipped).
127 int klassVtable::initialize_from_super(KlassHandle super) {
128 if (super.is_null()) {
129 return 0;
130 } else {
131 // copy methods from superKlass
132 klassVtable* superVtable = super->vtable();
133 assert(superVtable->length() <= _length, "vtable too short");
134 #ifdef ASSERT
135 superVtable->verify(tty, true);
136 #endif
137 superVtable->copy_vtable_to(table());
138 if (develop_log_is_enabled(Trace, vtables)) {
139 ResourceMark rm;
140 log_develop_trace(vtables)("copy vtable from %s to %s size %d",
141 super->internal_name(), klass()->internal_name(),
142 _length);
143 }
144 return superVtable->length();
145 }
146 }
147
148 //
149 // Revised lookup semantics introduced 1.3 (Kestrel beta)
150 void klassVtable::initialize_vtable(bool checkconstraints, TRAPS) {
151
152 // Note: Arrays can have intermediate array supers. Use java_super to skip them.
153 KlassHandle super (THREAD, klass()->java_super());
154 int nofNewEntries = 0;
155
156 if (!klass()->is_array_klass()) {
157 ResourceMark rm(THREAD);
158 log_develop_debug(vtables)("Initializing: %s", _klass->name()->as_C_string());
159 }
160
161 #ifdef ASSERT
162 oop* end_of_obj = (oop*)_klass() + _klass()->size();
163 oop* end_of_vtable = (oop*)&table()[_length];
164 assert(end_of_vtable <= end_of_obj, "vtable extends beyond end");
165 #endif
166
167 if (Universe::is_bootstrapping()) {
168 // just clear everything
169 for (int i = 0; i < _length; i++) table()[i].clear();
170 return;
171 }
172
173 int super_vtable_len = initialize_from_super(super);
174 if (klass()->is_array_klass()) {
175 assert(super_vtable_len == _length, "arrays shouldn't introduce new methods");
176 } else {
177 assert(_klass->is_instance_klass(), "must be InstanceKlass");
178
179 Array<Method*>* methods = ik()->methods();
180 int len = methods->length();
181 int initialized = super_vtable_len;
182
183 // Check each of this class's methods against super;
184 // if override, replace in copy of super vtable, otherwise append to end
185 for (int i = 0; i < len; i++) {
186 // update_inherited_vtable can stop for gc - ensure using handles
187 HandleMark hm(THREAD);
188 assert(methods->at(i)->is_method(), "must be a Method*");
189 methodHandle mh(THREAD, methods->at(i));
190
191 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, -1, checkconstraints, CHECK);
192
193 if (needs_new_entry) {
194 put_method_at(mh(), initialized);
195 mh()->set_vtable_index(initialized); // set primary vtable index
196 initialized++;
197 }
198 }
199
200 // update vtable with default_methods
201 Array<Method*>* default_methods = ik()->default_methods();
202 if (default_methods != NULL) {
203 len = default_methods->length();
204 if (len > 0) {
205 Array<int>* def_vtable_indices = NULL;
206 if ((def_vtable_indices = ik()->default_vtable_indices()) == NULL) {
207 def_vtable_indices = ik()->create_new_default_vtable_indices(len, CHECK);
208 } else {
209 assert(def_vtable_indices->length() == len, "reinit vtable len?");
210 }
211 for (int i = 0; i < len; i++) {
212 HandleMark hm(THREAD);
213 assert(default_methods->at(i)->is_method(), "must be a Method*");
214 methodHandle mh(THREAD, default_methods->at(i));
215
216 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, i, checkconstraints, CHECK);
217
218 // needs new entry
219 if (needs_new_entry) {
220 put_method_at(mh(), initialized);
221 def_vtable_indices->at_put(i, initialized); //set vtable index
222 initialized++;
223 }
224 }
225 }
226 }
227
228 // add miranda methods; it will also return the updated initialized
229 // Interfaces do not need interface methods in their vtables
230 // This includes miranda methods and during later processing, default methods
231 if (!ik()->is_interface()) {
232 initialized = fill_in_mirandas(initialized);
233 }
234
235 // In class hierarchies where the accessibility is not increasing (i.e., going from private ->
236 // package_private -> public/protected), the vtable might actually be smaller than our initial
237 // calculation.
238 assert(initialized <= _length, "vtable initialization failed");
239 for(;initialized < _length; initialized++) {
240 put_method_at(NULL, initialized);
241 }
242 NOT_PRODUCT(verify(tty, true));
243 }
244 }
245
246 // Called for cases where a method does not override its superclass' vtable entry
247 // For bytecodes not produced by javac together it is possible that a method does not override
248 // the superclass's method, but might indirectly override a super-super class's vtable entry
249 // If none found, return a null superk, else return the superk of the method this does override
250 // For public and protected methods: if they override a superclass, they will
251 // also be overridden themselves appropriately.
252 // Private methods do not override and are not overridden.
253 // Package Private methods are trickier:
254 // e.g. P1.A, pub m
255 // P2.B extends A, package private m
256 // P1.C extends B, public m
257 // P1.C.m needs to override P1.A.m and can not override P2.B.m
258 // Therefore: all package private methods need their own vtable entries for
259 // them to be the root of an inheritance overriding decision
260 // Package private methods may also override other vtable entries
261 InstanceKlass* klassVtable::find_transitive_override(InstanceKlass* initialsuper, methodHandle target_method,
262 int vtable_index, Handle target_loader, Symbol* target_classname, Thread * THREAD) {
263 InstanceKlass* superk = initialsuper;
264 while (superk != NULL && superk->super() != NULL) {
265 InstanceKlass* supersuperklass = InstanceKlass::cast(superk->super());
266 klassVtable* ssVtable = supersuperklass->vtable();
267 if (vtable_index < ssVtable->length()) {
268 Method* super_method = ssVtable->method_at(vtable_index);
269 #ifndef PRODUCT
270 Symbol* name= target_method()->name();
271 Symbol* signature = target_method()->signature();
272 assert(super_method->name() == name && super_method->signature() == signature, "vtable entry name/sig mismatch");
273 #endif
274 if (supersuperklass->is_override(super_method, target_loader, target_classname, THREAD)) {
275 if (develop_log_is_enabled(Trace, vtables)) {
276 ResourceMark rm(THREAD);
277 outputStream* logst = LogHandle(vtables)::trace_stream();
278 char* sig = target_method()->name_and_sig_as_C_string();
279 logst->print("transitive overriding superclass %s with %s::%s index %d, original flags: ",
280 supersuperklass->internal_name(),
281 _klass->internal_name(), sig, vtable_index);
282 super_method->print_linkage_flags(logst);
283 logst->print("overriders flags: ");
284 target_method->print_linkage_flags(logst);
285 logst->cr();
286 }
287
288 break; // return found superk
289 }
290 } else {
291 // super class has no vtable entry here, stop transitive search
292 superk = (InstanceKlass*)NULL;
293 break;
294 }
295 // if no override found yet, continue to search up
296 superk = superk->super() == NULL ? NULL : InstanceKlass::cast(superk->super());
297 }
298
299 return superk;
300 }
301
302 static void log_vtables(int i, bool overrides, methodHandle target_method,
303 KlassHandle target_klass, Method* super_method,
304 Thread* thread) {
305 #ifndef PRODUCT
306 if (develop_log_is_enabled(Trace, vtables)) {
307 ResourceMark rm(thread);
308 outputStream* logst = LogHandle(vtables)::trace_stream();
309 char* sig = target_method()->name_and_sig_as_C_string();
310 if (overrides) {
311 logst->print("overriding with %s::%s index %d, original flags: ",
312 target_klass->internal_name(), sig, i);
313 } else {
314 logst->print("NOT overriding with %s::%s index %d, original flags: ",
315 target_klass->internal_name(), sig, i);
316 }
317 super_method->print_linkage_flags(logst);
318 logst->print("overriders flags: ");
319 target_method->print_linkage_flags(logst);
320 logst->cr();
321 }
322 #endif
323 }
324
325 // Update child's copy of super vtable for overrides
326 // OR return true if a new vtable entry is required.
327 // Only called for InstanceKlass's, i.e. not for arrays
328 // If that changed, could not use _klass as handle for klass
329 bool klassVtable::update_inherited_vtable(InstanceKlass* klass, methodHandle target_method,
330 int super_vtable_len, int default_index,
331 bool checkconstraints, TRAPS) {
332 ResourceMark rm;
333 bool allocate_new = true;
334 assert(klass->is_instance_klass(), "must be InstanceKlass");
335
336 Array<int>* def_vtable_indices = NULL;
337 bool is_default = false;
338 // default methods are concrete methods in superinterfaces which are added to the vtable
339 // with their real method_holder
340 // Since vtable and itable indices share the same storage, don't touch
341 // the default method's real vtable/itable index
342 // default_vtable_indices stores the vtable value relative to this inheritor
343 if (default_index >= 0 ) {
344 is_default = true;
345 def_vtable_indices = klass->default_vtable_indices();
346 assert(def_vtable_indices != NULL, "def vtable alloc?");
347 assert(default_index <= def_vtable_indices->length(), "def vtable len?");
348 } else {
349 assert(klass == target_method()->method_holder(), "caller resp.");
350 // Initialize the method's vtable index to "nonvirtual".
351 // If we allocate a vtable entry, we will update it to a non-negative number.
352 target_method()->set_vtable_index(Method::nonvirtual_vtable_index);
353 }
354
355 // Static and <init> methods are never in
356 if (target_method()->is_static() || target_method()->name() == vmSymbols::object_initializer_name()) {
357 return false;
358 }
359
360 if (target_method->is_final_method(klass->access_flags())) {
361 // a final method never needs a new entry; final methods can be statically
362 // resolved and they have to be present in the vtable only if they override
363 // a super's method, in which case they re-use its entry
364 allocate_new = false;
365 } else if (klass->is_interface()) {
366 allocate_new = false; // see note below in needs_new_vtable_entry
367 // An interface never allocates new vtable slots, only inherits old ones.
368 // This method will either be assigned its own itable index later,
369 // or be assigned an inherited vtable index in the loop below.
370 // default methods inherited by classes store their vtable indices
371 // in the inheritor's default_vtable_indices
372 // default methods inherited by interfaces may already have a
373 // valid itable index, if so, don't change it
374 // overpass methods in an interface will be assigned an itable index later
375 // by an inheriting class
376 if (!is_default || !target_method()->has_itable_index()) {
377 target_method()->set_vtable_index(Method::pending_itable_index);
378 }
379 }
380
381 // we need a new entry if there is no superclass
382 if (klass->super() == NULL) {
383 return allocate_new;
384 }
385
386 // private methods in classes always have a new entry in the vtable
387 // specification interpretation since classic has
388 // private methods not overriding
389 // JDK8 adds private methods in interfaces which require invokespecial
390 if (target_method()->is_private()) {
391 return allocate_new;
392 }
393
394 // search through the vtable and update overridden entries
395 // Since check_signature_loaders acquires SystemDictionary_lock
396 // which can block for gc, once we are in this loop, use handles
397 // For classfiles built with >= jdk7, we now look for transitive overrides
398
399 Symbol* name = target_method()->name();
400 Symbol* signature = target_method()->signature();
401
402 KlassHandle target_klass(THREAD, target_method()->method_holder());
403 if (target_klass == NULL) {
404 target_klass = _klass;
405 }
406
407 Handle target_loader(THREAD, target_klass->class_loader());
408
409 Symbol* target_classname = target_klass->name();
410 for(int i = 0; i < super_vtable_len; i++) {
411 Method* super_method = method_at(i);
412 // Check if method name matches
413 if (super_method->name() == name && super_method->signature() == signature) {
414
415 // get super_klass for method_holder for the found method
416 InstanceKlass* super_klass = super_method->method_holder();
417
418 // Whether the method is being overridden
419 bool overrides = false;
420
421 // private methods are also never overridden
422 if (!super_method->is_private() &&
423 (is_default
424 || ((super_klass->is_override(super_method, target_loader, target_classname, THREAD))
425 || ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION)
426 && ((super_klass = find_transitive_override(super_klass,
427 target_method, i, target_loader,
428 target_classname, THREAD))
429 != (InstanceKlass*)NULL)))))
430 {
431 // Package private methods always need a new entry to root their own
432 // overriding. They may also override other methods.
433 if (!target_method()->is_package_private()) {
434 allocate_new = false;
435 }
436
437 if (checkconstraints) {
438 // Override vtable entry if passes loader constraint check
439 // if loader constraint checking requested
440 // No need to visit his super, since he and his super
441 // have already made any needed loader constraints.
442 // Since loader constraints are transitive, it is enough
443 // to link to the first super, and we get all the others.
444 Handle super_loader(THREAD, super_klass->class_loader());
445
446 if (target_loader() != super_loader()) {
447 ResourceMark rm(THREAD);
448 Symbol* failed_type_symbol =
449 SystemDictionary::check_signature_loaders(signature, target_loader,
450 super_loader, true,
451 CHECK_(false));
452 if (failed_type_symbol != NULL) {
453 const char* msg = "loader constraint violation: when resolving "
454 "overridden method \"%s\" the class loader (instance"
455 " of %s) of the current class, %s, and its superclass loader "
456 "(instance of %s), have different Class objects for the type "
457 "%s used in the signature";
458 char* sig = target_method()->name_and_sig_as_C_string();
459 const char* loader1 = SystemDictionary::loader_name(target_loader());
460 char* current = target_klass->name()->as_C_string();
461 const char* loader2 = SystemDictionary::loader_name(super_loader());
462 char* failed_type_name = failed_type_symbol->as_C_string();
463 size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) +
464 strlen(current) + strlen(loader2) + strlen(failed_type_name);
465 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
466 jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2,
467 failed_type_name);
468 THROW_MSG_(vmSymbols::java_lang_LinkageError(), buf, false);
469 }
470 }
471 }
472
473 put_method_at(target_method(), i);
474 overrides = true;
475 if (!is_default) {
476 target_method()->set_vtable_index(i);
477 } else {
478 if (def_vtable_indices != NULL) {
479 def_vtable_indices->at_put(default_index, i);
480 }
481 assert(super_method->is_default_method() || super_method->is_overpass()
482 || super_method->is_abstract(), "default override error");
483 }
484 } else {
485 overrides = false;
486 }
487 log_vtables(i, overrides, target_method, target_klass, super_method, THREAD);
488 }
489 }
490 return allocate_new;
491 }
492
493 void klassVtable::put_method_at(Method* m, int index) {
494 if (develop_log_is_enabled(Trace, vtables)) {
495 ResourceMark rm;
496 outputStream* logst = LogHandle(vtables)::trace_stream();
497 const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>";
498 logst->print("adding %s at index %d, flags: ", sig, index);
499 if (m != NULL) {
500 m->print_linkage_flags(logst);
501 }
502 logst->cr();
503 }
504 table()[index].set(m);
505 }
506
507 // Find out if a method "m" with superclass "super", loader "classloader" and
508 // name "classname" needs a new vtable entry. Let P be a class package defined
509 // by "classloader" and "classname".
510 // NOTE: The logic used here is very similar to the one used for computing
511 // the vtables indices for a method. We cannot directly use that function because,
512 // we allocate the InstanceKlass at load time, and that requires that the
513 // superclass has been loaded.
514 // However, the vtable entries are filled in at link time, and therefore
515 // the superclass' vtable may not yet have been filled in.
516 bool klassVtable::needs_new_vtable_entry(methodHandle target_method,
517 const Klass* super,
518 Handle classloader,
519 Symbol* classname,
520 AccessFlags class_flags,
521 TRAPS) {
522 if (class_flags.is_interface()) {
523 // Interfaces do not use vtables, except for java.lang.Object methods,
524 // so there is no point to assigning
525 // a vtable index to any of their local methods. If we refrain from doing this,
526 // we can use Method::_vtable_index to hold the itable index
527 return false;
528 }
529
530 if (target_method->is_final_method(class_flags) ||
531 // a final method never needs a new entry; final methods can be statically
532 // resolved and they have to be present in the vtable only if they override
533 // a super's method, in which case they re-use its entry
534 (target_method()->is_static()) ||
535 // static methods don't need to be in vtable
536 (target_method()->name() == vmSymbols::object_initializer_name())
537 // <init> is never called dynamically-bound
538 ) {
539 return false;
540 }
541
542 // Concrete interface methods do not need new entries, they override
543 // abstract method entries using default inheritance rules
544 if (target_method()->method_holder() != NULL &&
545 target_method()->method_holder()->is_interface() &&
546 !target_method()->is_abstract() ) {
547 return false;
548 }
549
550 // we need a new entry if there is no superclass
551 if (super == NULL) {
552 return true;
553 }
554
555 // private methods in classes always have a new entry in the vtable
556 // specification interpretation since classic has
557 // private methods not overriding
558 // JDK8 adds private methods in interfaces which require invokespecial
559 if (target_method()->is_private()) {
560 return true;
561 }
562
563 // Package private methods always need a new entry to root their own
564 // overriding. This allows transitive overriding to work.
565 if (target_method()->is_package_private()) {
566 return true;
567 }
568
569 // search through the super class hierarchy to see if we need
570 // a new entry
571 ResourceMark rm;
572 Symbol* name = target_method()->name();
573 Symbol* signature = target_method()->signature();
574 const Klass* k = super;
575 Method* super_method = NULL;
576 InstanceKlass *holder = NULL;
577 Method* recheck_method = NULL;
578 while (k != NULL) {
579 // lookup through the hierarchy for a method with matching name and sign.
580 super_method = InstanceKlass::cast(k)->lookup_method(name, signature);
581 if (super_method == NULL) {
582 break; // we still have to search for a matching miranda method
583 }
584 // get the class holding the matching method
585 // make sure you use that class for is_override
586 InstanceKlass* superk = super_method->method_holder();
587 // we want only instance method matches
588 // pretend private methods are not in the super vtable
589 // since we do override around them: e.g. a.m pub/b.m private/c.m pub,
590 // ignore private, c.m pub does override a.m pub
591 // For classes that were not javac'd together, we also do transitive overriding around
592 // methods that have less accessibility
593 if ((!super_method->is_static()) &&
594 (!super_method->is_private())) {
595 if (superk->is_override(super_method, classloader, classname, THREAD)) {
596 return false;
597 // else keep looking for transitive overrides
598 }
599 }
600
601 // Start with lookup result and continue to search up
602 k = superk->super(); // haven't found an override match yet; continue to look
603 }
604
605 // if the target method is public or protected it may have a matching
606 // miranda method in the super, whose entry it should re-use.
607 // Actually, to handle cases that javac would not generate, we need
608 // this check for all access permissions.
609 const InstanceKlass *sk = InstanceKlass::cast(super);
610 if (sk->has_miranda_methods()) {
611 if (sk->lookup_method_in_all_interfaces(name, signature, Klass::find_defaults) != NULL) {
612 return false; // found a matching miranda; we do not need a new entry
613 }
614 }
615 return true; // found no match; we need a new entry
616 }
617
618 // Support for miranda methods
619
620 // get the vtable index of a miranda method with matching "name" and "signature"
621 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) {
622 // search from the bottom, might be faster
623 for (int i = (length() - 1); i >= 0; i--) {
624 Method* m = table()[i].method();
625 if (is_miranda_entry_at(i) &&
626 m->name() == name && m->signature() == signature) {
627 return i;
628 }
629 }
630 return Method::invalid_vtable_index;
631 }
632
633 // check if an entry at an index is miranda
634 // requires that method m at entry be declared ("held") by an interface.
635 bool klassVtable::is_miranda_entry_at(int i) {
636 Method* m = method_at(i);
637 Klass* method_holder = m->method_holder();
638 InstanceKlass *mhk = InstanceKlass::cast(method_holder);
639
640 // miranda methods are public abstract instance interface methods in a class's vtable
641 if (mhk->is_interface()) {
642 assert(m->is_public(), "should be public");
643 assert(ik()->implements_interface(method_holder) , "this class should implement the interface");
644 if (is_miranda(m, ik()->methods(), ik()->default_methods(), ik()->super())) {
645 return true;
646 }
647 }
648 return false;
649 }
650
651 // Check if a method is a miranda method, given a class's methods array,
652 // its default_method table and its super class.
653 // "Miranda" means an abstract non-private method that would not be
654 // overridden for the local class.
655 // A "miranda" method should only include non-private interface
656 // instance methods, i.e. not private methods, not static methods,
657 // not default methods (concrete interface methods), not overpass methods.
658 // If a given class already has a local (including overpass) method, a
659 // default method, or any of its superclasses has the same which would have
660 // overridden an abstract method, then this is not a miranda method.
661 //
662 // Miranda methods are checked multiple times.
663 // Pass 1: during class load/class file parsing: before vtable size calculation:
664 // include superinterface abstract and default methods (non-private instance).
665 // We include potential default methods to give them space in the vtable.
666 // During the first run, the current instanceKlass has not yet been
667 // created, the superclasses and superinterfaces do have instanceKlasses
668 // but may not have vtables, the default_methods list is empty, no overpasses.
669 // This is seen by default method creation.
670 //
671 // Pass 2: recalculated during vtable initialization: only include abstract methods.
672 // The goal of pass 2 is to walk through the superinterfaces to see if any of
673 // the superinterface methods (which were all abstract pre-default methods)
674 // need to be added to the vtable.
675 // With the addition of default methods, we have three new challenges:
676 // overpasses, static interface methods and private interface methods.
677 // Static and private interface methods do not get added to the vtable and
678 // are not seen by the method resolution process, so we skip those.
679 // Overpass methods are already in the vtable, so vtable lookup will
680 // find them and we don't need to add a miranda method to the end of
681 // the vtable. So we look for overpass methods and if they are found we
682 // return false. Note that we inherit our superclasses vtable, so
683 // the superclass' search also needs to use find_overpass so that if
684 // one is found we return false.
685 // False means - we don't need a miranda method added to the vtable.
686 //
687 // During the second run, default_methods is set up, so concrete methods from
688 // superinterfaces with matching names/signatures to default_methods are already
689 // in the default_methods list and do not need to be appended to the vtable
690 // as mirandas. Abstract methods may already have been handled via
691 // overpasses - either local or superclass overpasses, which may be
692 // in the vtable already.
693 //
694 // Pass 3: They are also checked by link resolution and selection,
695 // for invocation on a method (not interface method) reference that
696 // resolves to a method with an interface as its method_holder.
697 // Used as part of walking from the bottom of the vtable to find
698 // the vtable index for the miranda method.
699 //
700 // Part of the Miranda Rights in the US mean that if you do not have
701 // an attorney one will be appointed for you.
702 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods,
703 Array<Method*>* default_methods, const Klass* super) {
704 if (m->is_static() || m->is_private() || m->is_overpass()) {
705 return false;
706 }
707 Symbol* name = m->name();
708 Symbol* signature = m->signature();
709
710 // First look in local methods to see if already covered
711 if (InstanceKlass::find_local_method(class_methods, name, signature,
712 Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL)
713 {
714 return false;
715 }
716
717 // Check local default methods
718 if ((default_methods != NULL) &&
719 (InstanceKlass::find_method(default_methods, name, signature) != NULL))
720 {
721 return false;
722 }
723
724 // Iterate on all superclasses, which should be InstanceKlasses.
725 // Note that we explicitly look for overpasses at each level.
726 // Overpasses may or may not exist for supers for pass 1,
727 // they should have been created for pass 2 and later.
728
729 for (const Klass* cursuper = super; cursuper != NULL; cursuper = cursuper->super())
730 {
731 if (InstanceKlass::cast(cursuper)->find_local_method(name, signature,
732 Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL) {
733 return false;
734 }
735 }
736
737 return true;
738 }
739
740 // Scans current_interface_methods for miranda methods that do not
741 // already appear in new_mirandas, or default methods, and are also not defined-and-non-private
742 // in super (superclass). These mirandas are added to all_mirandas if it is
743 // not null; in addition, those that are not duplicates of miranda methods
744 // inherited by super from its interfaces are added to new_mirandas.
745 // Thus, new_mirandas will be the set of mirandas that this class introduces,
746 // all_mirandas will be the set of all mirandas applicable to this class
747 // including all defined in superclasses.
748 void klassVtable::add_new_mirandas_to_lists(
749 GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas,
750 Array<Method*>* current_interface_methods, Array<Method*>* class_methods,
751 Array<Method*>* default_methods, const Klass* super) {
752
753 // iterate thru the current interface's method to see if it a miranda
754 int num_methods = current_interface_methods->length();
755 for (int i = 0; i < num_methods; i++) {
756 Method* im = current_interface_methods->at(i);
757 bool is_duplicate = false;
758 int num_of_current_mirandas = new_mirandas->length();
759 // check for duplicate mirandas in different interfaces we implement
760 for (int j = 0; j < num_of_current_mirandas; j++) {
761 Method* miranda = new_mirandas->at(j);
762 if ((im->name() == miranda->name()) &&
763 (im->signature() == miranda->signature())) {
764 is_duplicate = true;
765 break;
766 }
767 }
768
769 if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable
770 if (is_miranda(im, class_methods, default_methods, super)) { // is it a miranda at all?
771 const InstanceKlass *sk = InstanceKlass::cast(super);
772 // check if it is a duplicate of a super's miranda
773 if (sk->lookup_method_in_all_interfaces(im->name(), im->signature(), Klass::find_defaults) == NULL) {
774 new_mirandas->append(im);
775 }
776 if (all_mirandas != NULL) {
777 all_mirandas->append(im);
778 }
779 }
780 }
781 }
782 }
783
784 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas,
785 GrowableArray<Method*>* all_mirandas,
786 const Klass* super,
787 Array<Method*>* class_methods,
788 Array<Method*>* default_methods,
789 Array<Klass*>* local_interfaces) {
790 assert((new_mirandas->length() == 0) , "current mirandas must be 0");
791
792 // iterate thru the local interfaces looking for a miranda
793 int num_local_ifs = local_interfaces->length();
794 for (int i = 0; i < num_local_ifs; i++) {
795 InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i));
796 add_new_mirandas_to_lists(new_mirandas, all_mirandas,
797 ik->methods(), class_methods,
798 default_methods, super);
799 // iterate thru each local's super interfaces
800 Array<Klass*>* super_ifs = ik->transitive_interfaces();
801 int num_super_ifs = super_ifs->length();
802 for (int j = 0; j < num_super_ifs; j++) {
803 InstanceKlass *sik = InstanceKlass::cast(super_ifs->at(j));
804 add_new_mirandas_to_lists(new_mirandas, all_mirandas,
805 sik->methods(), class_methods,
806 default_methods, super);
807 }
808 }
809 }
810
811 // Discover miranda methods ("miranda" = "interface abstract, no binding"),
812 // and append them into the vtable starting at index initialized,
813 // return the new value of initialized.
814 // Miranda methods use vtable entries, but do not get assigned a vtable_index
815 // The vtable_index is discovered by searching from the end of the vtable
816 int klassVtable::fill_in_mirandas(int initialized) {
817 GrowableArray<Method*> mirandas(20);
818 get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(),
819 ik()->default_methods(), ik()->local_interfaces());
820 for (int i = 0; i < mirandas.length(); i++) {
821 if (develop_log_is_enabled(Trace, vtables)) {
822 Method* meth = mirandas.at(i);
823 ResourceMark rm(Thread::current());
824 outputStream* logst = LogHandle(vtables)::trace_stream();
825 if (meth != NULL) {
826 char* sig = meth->name_and_sig_as_C_string();
827 logst->print("fill in mirandas with %s index %d, flags: ",
828 sig, initialized);
829 meth->print_linkage_flags(logst);
830 logst->cr();
831 }
832 }
833 put_method_at(mirandas.at(i), initialized);
834 ++initialized;
835 }
836 return initialized;
837 }
838
839 // Copy this class's vtable to the vtable beginning at start.
840 // Used to copy superclass vtable to prefix of subclass's vtable.
841 void klassVtable::copy_vtable_to(vtableEntry* start) {
842 Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size());
843 }
844
845 #if INCLUDE_JVMTI
846 bool klassVtable::adjust_default_method(int vtable_index, Method* old_method, Method* new_method) {
847 // If old_method is default, find this vtable index in default_vtable_indices
848 // and replace that method in the _default_methods list
849 bool updated = false;
850
851 Array<Method*>* default_methods = ik()->default_methods();
852 if (default_methods != NULL) {
853 int len = default_methods->length();
854 for (int idx = 0; idx < len; idx++) {
855 if (vtable_index == ik()->default_vtable_indices()->at(idx)) {
856 if (default_methods->at(idx) == old_method) {
857 default_methods->at_put(idx, new_method);
858 updated = true;
859 }
860 break;
861 }
862 }
863 }
864 return updated;
865 }
866
867 // search the vtable for uses of either obsolete or EMCP methods
868 void klassVtable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) {
869 int prn_enabled = 0;
870 for (int index = 0; index < length(); index++) {
871 Method* old_method = unchecked_method_at(index);
872 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) {
873 continue; // skip uninteresting entries
874 }
875 assert(!old_method->is_deleted(), "vtable methods may not be deleted");
876
877 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum());
878
879 assert(new_method != NULL, "method_with_idnum() should not be NULL");
880 assert(old_method != new_method, "sanity check");
881
882 put_method_at(new_method, index);
883 // For default methods, need to update the _default_methods array
884 // which can only have one method entry for a given signature
885 bool updated_default = false;
886 if (old_method->is_default_method()) {
887 updated_default = adjust_default_method(index, old_method, new_method);
888 }
889
890 if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) {
891 if (!(*trace_name_printed)) {
892 // RC_TRACE_MESG macro has an embedded ResourceMark
893 RC_TRACE_MESG(("adjust: klassname=%s for methods from name=%s",
894 klass()->external_name(),
895 old_method->method_holder()->external_name()));
896 *trace_name_printed = true;
897 }
898 // RC_TRACE macro has an embedded ResourceMark
899 RC_TRACE(0x00100000, ("vtable method update: %s(%s), updated default = %s",
900 new_method->name()->as_C_string(),
901 new_method->signature()->as_C_string(),
902 updated_default ? "true" : "false"));
903 }
904 }
905 }
906
907 // a vtable should never contain old or obsolete methods
908 bool klassVtable::check_no_old_or_obsolete_entries() {
909 for (int i = 0; i < length(); i++) {
910 Method* m = unchecked_method_at(i);
911 if (m != NULL &&
912 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
913 return false;
914 }
915 }
916 return true;
917 }
918
919 void klassVtable::dump_vtable() {
920 tty->print_cr("vtable dump --");
921 for (int i = 0; i < length(); i++) {
922 Method* m = unchecked_method_at(i);
923 if (m != NULL) {
924 tty->print(" (%5d) ", i);
925 m->access_flags().print_on(tty);
926 if (m->is_default_method()) {
927 tty->print("default ");
928 }
929 if (m->is_overpass()) {
930 tty->print("overpass");
931 }
932 tty->print(" -- ");
933 m->print_name(tty);
934 tty->cr();
935 }
936 }
937 }
938 #endif // INCLUDE_JVMTI
939
940 // CDS/RedefineClasses support - clear vtables so they can be reinitialized
941 void klassVtable::clear_vtable() {
942 for (int i = 0; i < _length; i++) table()[i].clear();
943 }
944
945 bool klassVtable::is_initialized() {
946 return _length == 0 || table()[0].method() != NULL;
947 }
948
949 //-----------------------------------------------------------------------------------------
950 // Itable code
951
952 // Initialize a itableMethodEntry
953 void itableMethodEntry::initialize(Method* m) {
954 if (m == NULL) return;
955
956 _method = m;
957 }
958
959 klassItable::klassItable(instanceKlassHandle klass) {
960 _klass = klass;
961
962 if (klass->itable_length() > 0) {
963 itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable();
964 if (offset_entry != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized
965 // First offset entry points to the first method_entry
966 intptr_t* method_entry = (intptr_t *)(((address)klass()) + offset_entry->offset());
967 intptr_t* end = klass->end_of_itable();
968
969 _table_offset = (intptr_t*)offset_entry - (intptr_t*)klass();
970 _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size();
971 _size_method_table = (end - method_entry) / itableMethodEntry::size();
972 assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation");
973 return;
974 }
975 }
976
977 // The length of the itable was either zero, or it has not yet been initialized.
978 _table_offset = 0;
979 _size_offset_table = 0;
980 _size_method_table = 0;
981 }
982
983 static int initialize_count = 0;
984
985 // Initialization
986 void klassItable::initialize_itable(bool checkconstraints, TRAPS) {
987 if (_klass->is_interface()) {
988 // This needs to go after vtable indices are assigned but
989 // before implementors need to know the number of itable indices.
990 assign_itable_indices_for_interface(_klass());
991 }
992
993 // Cannot be setup doing bootstrapping, interfaces don't have
994 // itables, and klass with only ones entry have empty itables
995 if (Universe::is_bootstrapping() ||
996 _klass->is_interface() ||
997 _klass->itable_length() == itableOffsetEntry::size()) return;
998
999 // There's alway an extra itable entry so we can null-terminate it.
1000 guarantee(size_offset_table() >= 1, "too small");
1001 int num_interfaces = size_offset_table() - 1;
1002 if (num_interfaces > 0) {
1003 log_develop_debug(itables)("%3d: Initializing itables for %s", ++initialize_count,
1004 _klass->name()->as_C_string());
1005
1006
1007 // Iterate through all interfaces
1008 int i;
1009 for(i = 0; i < num_interfaces; i++) {
1010 itableOffsetEntry* ioe = offset_entry(i);
1011 HandleMark hm(THREAD);
1012 KlassHandle interf_h (THREAD, ioe->interface_klass());
1013 assert(interf_h() != NULL && ioe->offset() != 0, "bad offset entry in itable");
1014 initialize_itable_for_interface(ioe->offset(), interf_h, checkconstraints, CHECK);
1015 }
1016
1017 }
1018 // Check that the last entry is empty
1019 itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1);
1020 guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing");
1021 }
1022
1023
1024 inline bool interface_method_needs_itable_index(Method* m) {
1025 if (m->is_static()) return false; // e.g., Stream.empty
1026 if (m->is_initializer()) return false; // <init> or <clinit>
1027 // If an interface redeclares a method from java.lang.Object,
1028 // it should already have a vtable index, don't touch it.
1029 // e.g., CharSequence.toString (from initialize_vtable)
1030 // if (m->has_vtable_index()) return false; // NO!
1031 return true;
1032 }
1033
1034 int klassItable::assign_itable_indices_for_interface(Klass* klass) {
1035 // an interface does not have an itable, but its methods need to be numbered
1036 log_develop_debug(itables)("%3d: Initializing itable indices for interface %s",
1037 ++initialize_count, klass->name()->as_C_string());
1038 Array<Method*>* methods = InstanceKlass::cast(klass)->methods();
1039 int nof_methods = methods->length();
1040 int ime_num = 0;
1041 for (int i = 0; i < nof_methods; i++) {
1042 Method* m = methods->at(i);
1043 if (interface_method_needs_itable_index(m)) {
1044 assert(!m->is_final_method(), "no final interface methods");
1045 // If m is already assigned a vtable index, do not disturb it.
1046 if (develop_log_is_enabled(Trace, itables)) {
1047 ResourceMark rm;
1048 outputStream* logst = LogHandle(itables)::trace_stream();
1049 assert(m != NULL, "methods can never be null");
1050 const char* sig = m->name_and_sig_as_C_string();
1051 if (m->has_vtable_index()) {
1052 logst->print("vtable index %d for method: %s, flags: ", m->vtable_index(), sig);
1053 } else {
1054 logst->print("itable index %d for method: %s, flags: ", ime_num, sig);
1055 }
1056 m->print_linkage_flags(logst);
1057 logst->cr();
1058 }
1059 if (!m->has_vtable_index()) {
1060 assert(m->vtable_index() == Method::pending_itable_index, "set by initialize_vtable");
1061 m->set_itable_index(ime_num);
1062 // Progress to next itable entry
1063 ime_num++;
1064 }
1065 }
1066 }
1067 assert(ime_num == method_count_for_interface(klass), "proper sizing");
1068 return ime_num;
1069 }
1070
1071 int klassItable::method_count_for_interface(Klass* interf) {
1072 assert(interf->is_instance_klass(), "must be");
1073 assert(interf->is_interface(), "must be");
1074 Array<Method*>* methods = InstanceKlass::cast(interf)->methods();
1075 int nof_methods = methods->length();
1076 int length = 0;
1077 while (nof_methods > 0) {
1078 Method* m = methods->at(nof_methods-1);
1079 if (m->has_itable_index()) {
1080 length = m->itable_index() + 1;
1081 break;
1082 }
1083 nof_methods -= 1;
1084 }
1085 #ifdef ASSERT
1086 int nof_methods_copy = nof_methods;
1087 while (nof_methods_copy > 0) {
1088 Method* mm = methods->at(--nof_methods_copy);
1089 assert(!mm->has_itable_index() || mm->itable_index() < length, "");
1090 }
1091 #endif //ASSERT
1092 // return the rightmost itable index, plus one; or 0 if no methods have
1093 // itable indices
1094 return length;
1095 }
1096
1097
1098 void klassItable::initialize_itable_for_interface(int method_table_offset, KlassHandle interf_h, bool checkconstraints, TRAPS) {
1099 Array<Method*>* methods = InstanceKlass::cast(interf_h())->methods();
1100 int nof_methods = methods->length();
1101 HandleMark hm;
1102 assert(nof_methods > 0, "at least one method must exist for interface to be in vtable");
1103 Handle interface_loader (THREAD, InstanceKlass::cast(interf_h())->class_loader());
1104
1105 int ime_count = method_count_for_interface(interf_h());
1106 for (int i = 0; i < nof_methods; i++) {
1107 Method* m = methods->at(i);
1108 methodHandle target;
1109 if (m->has_itable_index()) {
1110 // This search must match the runtime resolution, i.e. selection search for invokeinterface
1111 // to correctly enforce loader constraints for interface method inheritance
1112 target = LinkResolver::lookup_instance_method_in_klasses(_klass, m->name(), m->signature(), CHECK);
1113 }
1114 if (target == NULL || !target->is_public() || target->is_abstract()) {
1115 // Entry does not resolve. Leave it empty for AbstractMethodError.
1116 if (!(target == NULL) && !target->is_public()) {
1117 // Stuff an IllegalAccessError throwing method in there instead.
1118 itableOffsetEntry::method_entry(_klass(), method_table_offset)[m->itable_index()].
1119 initialize(Universe::throw_illegal_access_error());
1120 }
1121 } else {
1122 // Entry did resolve, check loader constraints before initializing
1123 // if checkconstraints requested
1124 if (checkconstraints) {
1125 Handle method_holder_loader (THREAD, target->method_holder()->class_loader());
1126 if (method_holder_loader() != interface_loader()) {
1127 ResourceMark rm(THREAD);
1128 Symbol* failed_type_symbol =
1129 SystemDictionary::check_signature_loaders(m->signature(),
1130 method_holder_loader,
1131 interface_loader,
1132 true, CHECK);
1133 if (failed_type_symbol != NULL) {
1134 const char* msg = "loader constraint violation in interface "
1135 "itable initialization: when resolving method \"%s\" the class"
1136 " loader (instance of %s) of the current class, %s, "
1137 "and the class loader (instance of %s) for interface "
1138 "%s have different Class objects for the type %s "
1139 "used in the signature";
1140 char* sig = target()->name_and_sig_as_C_string();
1141 const char* loader1 = SystemDictionary::loader_name(method_holder_loader());
1142 char* current = _klass->name()->as_C_string();
1143 const char* loader2 = SystemDictionary::loader_name(interface_loader());
1144 char* iface = InstanceKlass::cast(interf_h())->name()->as_C_string();
1145 char* failed_type_name = failed_type_symbol->as_C_string();
1146 size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) +
1147 strlen(current) + strlen(loader2) + strlen(iface) +
1148 strlen(failed_type_name);
1149 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
1150 jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2,
1151 iface, failed_type_name);
1152 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
1153 }
1154 }
1155 }
1156
1157 // ime may have moved during GC so recalculate address
1158 int ime_num = m->itable_index();
1159 assert(ime_num < ime_count, "oob");
1160 itableOffsetEntry::method_entry(_klass(), method_table_offset)[ime_num].initialize(target());
1161 if (develop_log_is_enabled(Trace, itables)) {
1162 ResourceMark rm(THREAD);
1163 if (target() != NULL) {
1164 outputStream* logst = LogHandle(itables)::trace_stream();
1165 char* sig = target()->name_and_sig_as_C_string();
1166 logst->print("interface: %s, ime_num: %d, target: %s, method_holder: %s ",
1167 interf_h()->internal_name(), ime_num, sig,
1168 target()->method_holder()->internal_name());
1169 logst->print("target_method flags: ");
1170 target()->print_linkage_flags(logst);
1171 logst->cr();
1172 }
1173 }
1174 }
1175 }
1176 }
1177
1178 // Update entry for specific Method*
1179 void klassItable::initialize_with_method(Method* m) {
1180 itableMethodEntry* ime = method_entry(0);
1181 for(int i = 0; i < _size_method_table; i++) {
1182 if (ime->method() == m) {
1183 ime->initialize(m);
1184 }
1185 ime++;
1186 }
1187 }
1188
1189 #if INCLUDE_JVMTI
1190 // search the itable for uses of either obsolete or EMCP methods
1191 void klassItable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) {
1192
1193 itableMethodEntry* ime = method_entry(0);
1194 for (int i = 0; i < _size_method_table; i++, ime++) {
1195 Method* old_method = ime->method();
1196 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) {
1197 continue; // skip uninteresting entries
1198 }
1199 assert(!old_method->is_deleted(), "itable methods may not be deleted");
1200
1201 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum());
1202
1203 assert(new_method != NULL, "method_with_idnum() should not be NULL");
1204 assert(old_method != new_method, "sanity check");
1205
1206 ime->initialize(new_method);
1207
1208 if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) {
1209 if (!(*trace_name_printed)) {
1210 // RC_TRACE_MESG macro has an embedded ResourceMark
1211 RC_TRACE_MESG(("adjust: name=%s",
1212 old_method->method_holder()->external_name()));
1213 *trace_name_printed = true;
1214 }
1215 // RC_TRACE macro has an embedded ResourceMark
1216 RC_TRACE(0x00200000, ("itable method update: %s(%s)",
1217 new_method->name()->as_C_string(),
1218 new_method->signature()->as_C_string()));
1219 }
1220 }
1221 }
1222
1223 // an itable should never contain old or obsolete methods
1224 bool klassItable::check_no_old_or_obsolete_entries() {
1225 itableMethodEntry* ime = method_entry(0);
1226 for (int i = 0; i < _size_method_table; i++) {
1227 Method* m = ime->method();
1228 if (m != NULL &&
1229 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
1230 return false;
1231 }
1232 ime++;
1233 }
1234 return true;
1235 }
1236
1237 void klassItable::dump_itable() {
1238 itableMethodEntry* ime = method_entry(0);
1239 tty->print_cr("itable dump --");
1240 for (int i = 0; i < _size_method_table; i++) {
1241 Method* m = ime->method();
1242 if (m != NULL) {
1243 tty->print(" (%5d) ", i);
1244 m->access_flags().print_on(tty);
1245 if (m->is_default_method()) {
1246 tty->print("default ");
1247 }
1248 tty->print(" -- ");
1249 m->print_name(tty);
1250 tty->cr();
1251 }
1252 ime++;
1253 }
1254 }
1255 #endif // INCLUDE_JVMTI
1256
1257
1258 // Setup
1259 class InterfaceVisiterClosure : public StackObj {
1260 public:
1261 virtual void doit(Klass* intf, int method_count) = 0;
1262 };
1263
1264 // Visit all interfaces with at least one itable method
1265 void visit_all_interfaces(Array<Klass*>* transitive_intf, InterfaceVisiterClosure *blk) {
1266 // Handle array argument
1267 for(int i = 0; i < transitive_intf->length(); i++) {
1268 Klass* intf = transitive_intf->at(i);
1269 assert(intf->is_interface(), "sanity check");
1270
1271 // Find no. of itable methods
1272 int method_count = 0;
1273 // method_count = klassItable::method_count_for_interface(intf);
1274 Array<Method*>* methods = InstanceKlass::cast(intf)->methods();
1275 if (methods->length() > 0) {
1276 for (int i = methods->length(); --i >= 0; ) {
1277 if (interface_method_needs_itable_index(methods->at(i))) {
1278 method_count++;
1279 }
1280 }
1281 }
1282
1283 // Only count interfaces with at least one method
1284 if (method_count > 0) {
1285 blk->doit(intf, method_count);
1286 }
1287 }
1288 }
1289
1290 class CountInterfacesClosure : public InterfaceVisiterClosure {
1291 private:
1292 int _nof_methods;
1293 int _nof_interfaces;
1294 public:
1295 CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; }
1296
1297 int nof_methods() const { return _nof_methods; }
1298 int nof_interfaces() const { return _nof_interfaces; }
1299
1300 void doit(Klass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; }
1301 };
1302
1303 class SetupItableClosure : public InterfaceVisiterClosure {
1304 private:
1305 itableOffsetEntry* _offset_entry;
1306 itableMethodEntry* _method_entry;
1307 address _klass_begin;
1308 public:
1309 SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) {
1310 _klass_begin = klass_begin;
1311 _offset_entry = offset_entry;
1312 _method_entry = method_entry;
1313 }
1314
1315 itableMethodEntry* method_entry() const { return _method_entry; }
1316
1317 void doit(Klass* intf, int method_count) {
1318 int offset = ((address)_method_entry) - _klass_begin;
1319 _offset_entry->initialize(intf, offset);
1320 _offset_entry++;
1321 _method_entry += method_count;
1322 }
1323 };
1324
1325 int klassItable::compute_itable_size(Array<Klass*>* transitive_interfaces) {
1326 // Count no of interfaces and total number of interface methods
1327 CountInterfacesClosure cic;
1328 visit_all_interfaces(transitive_interfaces, &cic);
1329
1330 // There's alway an extra itable entry so we can null-terminate it.
1331 int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods());
1332
1333 // Statistics
1334 update_stats(itable_size * HeapWordSize);
1335
1336 return itable_size;
1337 }
1338
1339
1340 // Fill out offset table and interface klasses into the itable space
1341 void klassItable::setup_itable_offset_table(instanceKlassHandle klass) {
1342 if (klass->itable_length() == 0) return;
1343 assert(!klass->is_interface(), "Should have zero length itable");
1344
1345 // Count no of interfaces and total number of interface methods
1346 CountInterfacesClosure cic;
1347 visit_all_interfaces(klass->transitive_interfaces(), &cic);
1348 int nof_methods = cic.nof_methods();
1349 int nof_interfaces = cic.nof_interfaces();
1350
1351 // Add one extra entry so we can null-terminate the table
1352 nof_interfaces++;
1353
1354 assert(compute_itable_size(klass->transitive_interfaces()) ==
1355 calc_itable_size(nof_interfaces, nof_methods),
1356 "mismatch calculation of itable size");
1357
1358 // Fill-out offset table
1359 itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable();
1360 itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces);
1361 intptr_t* end = klass->end_of_itable();
1362 assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)");
1363 assert((oop*)(end) == (oop*)(ime + nof_methods), "wrong offset calculation (2)");
1364
1365 // Visit all interfaces and initialize itable offset table
1366 SetupItableClosure sic((address)klass(), ioe, ime);
1367 visit_all_interfaces(klass->transitive_interfaces(), &sic);
1368
1369 #ifdef ASSERT
1370 ime = sic.method_entry();
1371 oop* v = (oop*) klass->end_of_itable();
1372 assert( (oop*)(ime) == v, "wrong offset calculation (2)");
1373 #endif
1374 }
1375
1376
1377 // inverse to itable_index
1378 Method* klassItable::method_for_itable_index(Klass* intf, int itable_index) {
1379 assert(InstanceKlass::cast(intf)->is_interface(), "sanity check");
1380 assert(intf->verify_itable_index(itable_index), "");
1381 Array<Method*>* methods = InstanceKlass::cast(intf)->methods();
1382
1383 if (itable_index < 0 || itable_index >= method_count_for_interface(intf))
1384 return NULL; // help caller defend against bad indices
1385
1386 int index = itable_index;
1387 Method* m = methods->at(index);
1388 int index2 = -1;
1389 while (!m->has_itable_index() ||
1390 (index2 = m->itable_index()) != itable_index) {
1391 assert(index2 < itable_index, "monotonic");
1392 if (++index == methods->length())
1393 return NULL;
1394 m = methods->at(index);
1395 }
1396 assert(m->itable_index() == itable_index, "correct inverse");
1397
1398 return m;
1399 }
1400
1401 void klassVtable::verify(outputStream* st, bool forced) {
1402 // make sure table is initialized
1403 if (!Universe::is_fully_initialized()) return;
1404 #ifndef PRODUCT
1405 // avoid redundant verifies
1406 if (!forced && _verify_count == Universe::verify_count()) return;
1407 _verify_count = Universe::verify_count();
1408 #endif
1409 oop* end_of_obj = (oop*)_klass() + _klass()->size();
1410 oop* end_of_vtable = (oop *)&table()[_length];
1411 if (end_of_vtable > end_of_obj) {
1412 fatal("klass %s: klass object too short (vtable extends beyond end)",
1413 _klass->internal_name());
1414 }
1415
1416 for (int i = 0; i < _length; i++) table()[i].verify(this, st);
1417 // verify consistency with superKlass vtable
1418 Klass* super = _klass->super();
1419 if (super != NULL) {
1420 InstanceKlass* sk = InstanceKlass::cast(super);
1421 klassVtable* vt = sk->vtable();
1422 for (int i = 0; i < vt->length(); i++) {
1423 verify_against(st, vt, i);
1424 }
1425 }
1426 }
1427
1428 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) {
1429 vtableEntry* vte = &vt->table()[index];
1430 if (vte->method()->name() != table()[index].method()->name() ||
1431 vte->method()->signature() != table()[index].method()->signature()) {
1432 fatal("mismatched name/signature of vtable entries");
1433 }
1434 }
1435
1436 #ifndef PRODUCT
1437 void klassVtable::print() {
1438 ResourceMark rm;
1439 tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length());
1440 for (int i = 0; i < length(); i++) {
1441 table()[i].print();
1442 tty->cr();
1443 }
1444 }
1445 #endif
1446
1447 void vtableEntry::verify(klassVtable* vt, outputStream* st) {
1448 NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true));
1449 assert(method() != NULL, "must have set method");
1450 method()->verify();
1451 // we sub_type, because it could be a miranda method
1452 if (!vt->klass()->is_subtype_of(method()->method_holder())) {
1453 #ifndef PRODUCT
1454 print();
1455 #endif
1456 fatal("vtableEntry " PTR_FORMAT ": method is from subclass", p2i(this));
1457 }
1458 }
1459
1460 #ifndef PRODUCT
1461
1462 void vtableEntry::print() {
1463 ResourceMark rm;
1464 tty->print("vtableEntry %s: ", method()->name()->as_C_string());
1465 if (Verbose) {
1466 tty->print("m " PTR_FORMAT " ", p2i(method()));
1467 }
1468 }
1469
1470 class VtableStats : AllStatic {
1471 public:
1472 static int no_klasses; // # classes with vtables
1473 static int no_array_klasses; // # array classes
1474 static int no_instance_klasses; // # instanceKlasses
1475 static int sum_of_vtable_len; // total # of vtable entries
1476 static int sum_of_array_vtable_len; // total # of vtable entries in array klasses only
1477 static int fixed; // total fixed overhead in bytes
1478 static int filler; // overhead caused by filler bytes
1479 static int entries; // total bytes consumed by vtable entries
1480 static int array_entries; // total bytes consumed by array vtable entries
1481
1482 static void do_class(Klass* k) {
1483 Klass* kl = k;
1484 klassVtable* vt = kl->vtable();
1485 if (vt == NULL) return;
1486 no_klasses++;
1487 if (kl->is_instance_klass()) {
1488 no_instance_klasses++;
1489 kl->array_klasses_do(do_class);
1490 }
1491 if (kl->is_array_klass()) {
1492 no_array_klasses++;
1493 sum_of_array_vtable_len += vt->length();
1494 }
1495 sum_of_vtable_len += vt->length();
1496 }
1497
1498 static void compute() {
1499 SystemDictionary::classes_do(do_class);
1500 fixed = no_klasses * oopSize; // vtable length
1501 // filler size is a conservative approximation
1502 filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(InstanceKlass) - sizeof(ArrayKlass) - 1);
1503 entries = sizeof(vtableEntry) * sum_of_vtable_len;
1504 array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len;
1505 }
1506 };
1507
1508 int VtableStats::no_klasses = 0;
1509 int VtableStats::no_array_klasses = 0;
1510 int VtableStats::no_instance_klasses = 0;
1511 int VtableStats::sum_of_vtable_len = 0;
1512 int VtableStats::sum_of_array_vtable_len = 0;
1513 int VtableStats::fixed = 0;
1514 int VtableStats::filler = 0;
1515 int VtableStats::entries = 0;
1516 int VtableStats::array_entries = 0;
1517
1518 void klassVtable::print_statistics() {
1519 ResourceMark rm;
1520 HandleMark hm;
1521 VtableStats::compute();
1522 tty->print_cr("vtable statistics:");
1523 tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses);
1524 int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries;
1525 tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed);
1526 tty->print_cr("%6d bytes filler overhead", VtableStats::filler);
1527 tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries);
1528 tty->print_cr("%6d bytes total", total);
1529 }
1530
1531 int klassItable::_total_classes; // Total no. of classes with itables
1532 long klassItable::_total_size; // Total no. of bytes used for itables
1533
1534 void klassItable::print_statistics() {
1535 tty->print_cr("itable statistics:");
1536 tty->print_cr("%6d classes with itables", _total_classes);
1537 tty->print_cr("%6lu K uses for itables (average by class: %ld bytes)", _total_size / K, _total_size / _total_classes);
1538 }
1539
1540 #endif // PRODUCT