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