1 /*
2 * Copyright 2005-2008 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 # include "incls/_precompiled.incl"
26 # include "incls/_dependencies.cpp.incl"
27
28
29 #ifdef ASSERT
30 static bool must_be_in_vm() {
31 Thread* thread = Thread::current();
32 if (thread->is_Java_thread())
33 return ((JavaThread*)thread)->thread_state() == _thread_in_vm;
34 else
35 return true; //something like this: thread->is_VM_thread();
36 }
37 #endif //ASSERT
38
39 void Dependencies::initialize(ciEnv* env) {
40 Arena* arena = env->arena();
41 _oop_recorder = env->oop_recorder();
42 _log = env->log();
43 _dep_seen = new(arena) GrowableArray<int>(arena, 500, 0, 0);
44 DEBUG_ONLY(_deps[end_marker] = NULL);
45 for (int i = (int)FIRST_TYPE; i < (int)TYPE_LIMIT; i++) {
46 _deps[i] = new(arena) GrowableArray<ciObject*>(arena, 10, 0, 0);
47 }
48 _content_bytes = NULL;
49 _size_in_bytes = (size_t)-1;
50
51 assert(TYPE_LIMIT <= (1<<LG2_TYPE_LIMIT), "sanity");
52 }
53
54 void Dependencies::assert_evol_method(ciMethod* m) {
55 assert_common_1(evol_method, m);
56 }
57
58 void Dependencies::assert_leaf_type(ciKlass* ctxk) {
59 if (ctxk->is_array_klass()) {
60 // As a special case, support this assertion on an array type,
61 // which reduces to an assertion on its element type.
62 // Note that this cannot be done with assertions that
63 // relate to concreteness or abstractness.
64 ciType* elemt = ctxk->as_array_klass()->base_element_type();
65 if (!elemt->is_instance_klass()) return; // Ex: int[][]
66 ctxk = elemt->as_instance_klass();
67 //if (ctxk->is_final()) return; // Ex: String[][]
68 }
69 check_ctxk(ctxk);
70 assert_common_1(leaf_type, ctxk);
71 }
72
73 void Dependencies::assert_abstract_with_unique_concrete_subtype(ciKlass* ctxk, ciKlass* conck) {
74 check_ctxk_abstract(ctxk);
75 assert_common_2(abstract_with_unique_concrete_subtype, ctxk, conck);
76 }
77
78 void Dependencies::assert_abstract_with_no_concrete_subtype(ciKlass* ctxk) {
79 check_ctxk_abstract(ctxk);
80 assert_common_1(abstract_with_no_concrete_subtype, ctxk);
81 }
82
83 void Dependencies::assert_concrete_with_no_concrete_subtype(ciKlass* ctxk) {
84 check_ctxk_concrete(ctxk);
85 assert_common_1(concrete_with_no_concrete_subtype, ctxk);
86 }
87
88 void Dependencies::assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm) {
89 check_ctxk(ctxk);
90 assert_common_2(unique_concrete_method, ctxk, uniqm);
91 }
92
93 void Dependencies::assert_abstract_with_exclusive_concrete_subtypes(ciKlass* ctxk, ciKlass* k1, ciKlass* k2) {
94 check_ctxk(ctxk);
95 assert_common_3(abstract_with_exclusive_concrete_subtypes_2, ctxk, k1, k2);
96 }
97
98 void Dependencies::assert_exclusive_concrete_methods(ciKlass* ctxk, ciMethod* m1, ciMethod* m2) {
99 check_ctxk(ctxk);
100 assert_common_3(exclusive_concrete_methods_2, ctxk, m1, m2);
101 }
102
103 void Dependencies::assert_has_no_finalizable_subclasses(ciKlass* ctxk) {
104 check_ctxk(ctxk);
105 assert_common_1(no_finalizable_subclasses, ctxk);
106 }
107
108 // Helper function. If we are adding a new dep. under ctxk2,
109 // try to find an old dep. under a broader* ctxk1. If there is
110 //
111 bool Dependencies::maybe_merge_ctxk(GrowableArray<ciObject*>* deps,
112 int ctxk_i, ciKlass* ctxk2) {
113 ciKlass* ctxk1 = deps->at(ctxk_i)->as_klass();
114 if (ctxk2->is_subtype_of(ctxk1)) {
115 return true; // success, and no need to change
116 } else if (ctxk1->is_subtype_of(ctxk2)) {
117 // new context class fully subsumes previous one
118 deps->at_put(ctxk_i, ctxk2);
119 return true;
120 } else {
121 return false;
122 }
123 }
124
125 void Dependencies::assert_common_1(Dependencies::DepType dept, ciObject* x) {
126 assert(dep_args(dept) == 1, "sanity");
127 log_dependency(dept, x);
128 GrowableArray<ciObject*>* deps = _deps[dept];
129
130 // see if the same (or a similar) dep is already recorded
131 if (note_dep_seen(dept, x)) {
132 assert(deps->find(x) >= 0, "sanity");
133 } else {
134 deps->append(x);
135 }
136 }
137
138 void Dependencies::assert_common_2(Dependencies::DepType dept,
139 ciKlass* ctxk, ciObject* x) {
140 assert(dep_context_arg(dept) == 0, "sanity");
141 assert(dep_args(dept) == 2, "sanity");
142 log_dependency(dept, ctxk, x);
143 GrowableArray<ciObject*>* deps = _deps[dept];
144
145 // see if the same (or a similar) dep is already recorded
146 if (note_dep_seen(dept, x)) {
147 // look in this bucket for redundant assertions
148 const int stride = 2;
149 for (int i = deps->length(); (i -= stride) >= 0; ) {
150 ciObject* x1 = deps->at(i+1);
151 if (x == x1) { // same subject; check the context
152 if (maybe_merge_ctxk(deps, i+0, ctxk)) {
153 return;
154 }
155 }
156 }
157 }
158
159 // append the assertion in the correct bucket:
160 deps->append(ctxk);
161 deps->append(x);
162 }
163
164 void Dependencies::assert_common_3(Dependencies::DepType dept,
165 ciKlass* ctxk, ciObject* x, ciObject* x2) {
166 assert(dep_context_arg(dept) == 0, "sanity");
167 assert(dep_args(dept) == 3, "sanity");
168 log_dependency(dept, ctxk, x, x2);
169 GrowableArray<ciObject*>* deps = _deps[dept];
170
171 // try to normalize an unordered pair:
172 bool swap = false;
173 switch (dept) {
174 case abstract_with_exclusive_concrete_subtypes_2:
175 swap = (x->ident() > x2->ident() && x != ctxk);
176 break;
177 case exclusive_concrete_methods_2:
178 swap = (x->ident() > x2->ident() && x->as_method()->holder() != ctxk);
179 break;
180 }
181 if (swap) { ciObject* t = x; x = x2; x2 = t; }
182
183 // see if the same (or a similar) dep is already recorded
184 if (note_dep_seen(dept, x) && note_dep_seen(dept, x2)) {
185 // look in this bucket for redundant assertions
186 const int stride = 3;
187 for (int i = deps->length(); (i -= stride) >= 0; ) {
188 ciObject* y = deps->at(i+1);
189 ciObject* y2 = deps->at(i+2);
190 if (x == y && x2 == y2) { // same subjects; check the context
191 if (maybe_merge_ctxk(deps, i+0, ctxk)) {
192 return;
193 }
194 }
195 }
196 }
197 // append the assertion in the correct bucket:
198 deps->append(ctxk);
199 deps->append(x);
200 deps->append(x2);
201 }
202
203 /// Support for encoding dependencies into an nmethod:
204
205 void Dependencies::copy_to(nmethod* nm) {
206 address beg = nm->dependencies_begin();
207 address end = nm->dependencies_end();
208 guarantee(end - beg >= (ptrdiff_t) size_in_bytes(), "bad sizing");
209 Copy::disjoint_words((HeapWord*) content_bytes(),
210 (HeapWord*) beg,
211 size_in_bytes() / sizeof(HeapWord));
212 assert(size_in_bytes() % sizeof(HeapWord) == 0, "copy by words");
213 }
214
215 static int sort_dep(ciObject** p1, ciObject** p2, int narg) {
216 for (int i = 0; i < narg; i++) {
217 int diff = p1[i]->ident() - p2[i]->ident();
218 if (diff != 0) return diff;
219 }
220 return 0;
221 }
222 static int sort_dep_arg_1(ciObject** p1, ciObject** p2)
223 { return sort_dep(p1, p2, 1); }
224 static int sort_dep_arg_2(ciObject** p1, ciObject** p2)
225 { return sort_dep(p1, p2, 2); }
226 static int sort_dep_arg_3(ciObject** p1, ciObject** p2)
227 { return sort_dep(p1, p2, 3); }
228
229 void Dependencies::sort_all_deps() {
230 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
231 DepType dept = (DepType)deptv;
232 GrowableArray<ciObject*>* deps = _deps[dept];
233 if (deps->length() <= 1) continue;
234 switch (dep_args(dept)) {
235 case 1: deps->sort(sort_dep_arg_1, 1); break;
236 case 2: deps->sort(sort_dep_arg_2, 2); break;
237 case 3: deps->sort(sort_dep_arg_3, 3); break;
238 default: ShouldNotReachHere();
239 }
240 }
241 }
242
243 size_t Dependencies::estimate_size_in_bytes() {
244 size_t est_size = 100;
245 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
246 DepType dept = (DepType)deptv;
247 GrowableArray<ciObject*>* deps = _deps[dept];
248 est_size += deps->length()*2; // tags and argument(s)
249 }
250 return est_size;
251 }
252
253 ciKlass* Dependencies::ctxk_encoded_as_null(DepType dept, ciObject* x) {
254 switch (dept) {
255 case abstract_with_exclusive_concrete_subtypes_2:
256 return x->as_klass();
257 case unique_concrete_method:
258 case exclusive_concrete_methods_2:
259 return x->as_method()->holder();
260 }
261 return NULL; // let NULL be NULL
262 }
263
264 klassOop Dependencies::ctxk_encoded_as_null(DepType dept, oop x) {
265 assert(must_be_in_vm(), "raw oops here");
266 switch (dept) {
267 case abstract_with_exclusive_concrete_subtypes_2:
268 assert(x->is_klass(), "sanity");
269 return (klassOop) x;
270 case unique_concrete_method:
271 case exclusive_concrete_methods_2:
272 assert(x->is_method(), "sanity");
273 return ((methodOop)x)->method_holder();
274 }
275 return NULL; // let NULL be NULL
276 }
277
278 void Dependencies::encode_content_bytes() {
279 sort_all_deps();
280
281 // cast is safe, no deps can overflow INT_MAX
282 CompressedWriteStream bytes((int)estimate_size_in_bytes());
283
284 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
285 DepType dept = (DepType)deptv;
286 GrowableArray<ciObject*>* deps = _deps[dept];
287 if (deps->length() == 0) continue;
288 int stride = dep_args(dept);
289 int ctxkj = dep_context_arg(dept); // -1 if no context arg
290 assert(stride > 0, "sanity");
291 for (int i = 0; i < deps->length(); i += stride) {
292 jbyte code_byte = (jbyte)dept;
293 int skipj = -1;
294 if (ctxkj >= 0 && ctxkj+1 < stride) {
295 ciKlass* ctxk = deps->at(i+ctxkj+0)->as_klass();
296 ciObject* x = deps->at(i+ctxkj+1); // following argument
297 if (ctxk == ctxk_encoded_as_null(dept, x)) {
298 skipj = ctxkj; // we win: maybe one less oop to keep track of
299 code_byte |= default_context_type_bit;
300 }
301 }
302 bytes.write_byte(code_byte);
303 for (int j = 0; j < stride; j++) {
304 if (j == skipj) continue;
305 bytes.write_int(_oop_recorder->find_index(deps->at(i+j)->constant_encoding()));
306 }
307 }
308 }
309
310 // write a sentinel byte to mark the end
311 bytes.write_byte(end_marker);
312
313 // round it out to a word boundary
314 while (bytes.position() % sizeof(HeapWord) != 0) {
315 bytes.write_byte(end_marker);
316 }
317
318 // check whether the dept byte encoding really works
319 assert((jbyte)default_context_type_bit != 0, "byte overflow");
320
321 _content_bytes = bytes.buffer();
322 _size_in_bytes = bytes.position();
323 }
324
325
326 const char* Dependencies::_dep_name[TYPE_LIMIT] = {
327 "end_marker",
328 "evol_method",
329 "leaf_type",
330 "abstract_with_unique_concrete_subtype",
331 "abstract_with_no_concrete_subtype",
332 "concrete_with_no_concrete_subtype",
333 "unique_concrete_method",
334 "abstract_with_exclusive_concrete_subtypes_2",
335 "exclusive_concrete_methods_2",
336 "no_finalizable_subclasses"
337 };
338
339 int Dependencies::_dep_args[TYPE_LIMIT] = {
340 -1,// end_marker
341 1, // evol_method m
342 1, // leaf_type ctxk
343 2, // abstract_with_unique_concrete_subtype ctxk, k
344 1, // abstract_with_no_concrete_subtype ctxk
345 1, // concrete_with_no_concrete_subtype ctxk
346 2, // unique_concrete_method ctxk, m
347 3, // unique_concrete_subtypes_2 ctxk, k1, k2
348 3, // unique_concrete_methods_2 ctxk, m1, m2
349 1 // no_finalizable_subclasses ctxk
350 };
351
352 const char* Dependencies::dep_name(Dependencies::DepType dept) {
353 if (!dept_in_mask(dept, all_types)) return "?bad-dep?";
354 return _dep_name[dept];
355 }
356
357 int Dependencies::dep_args(Dependencies::DepType dept) {
358 if (!dept_in_mask(dept, all_types)) return -1;
359 return _dep_args[dept];
360 }
361
362 // for the sake of the compiler log, print out current dependencies:
363 void Dependencies::log_all_dependencies() {
364 if (log() == NULL) return;
365 ciObject* args[max_arg_count];
366 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
367 DepType dept = (DepType)deptv;
368 GrowableArray<ciObject*>* deps = _deps[dept];
369 if (deps->length() == 0) continue;
370 int stride = dep_args(dept);
371 for (int i = 0; i < deps->length(); i += stride) {
372 for (int j = 0; j < stride; j++) {
373 // flush out the identities before printing
374 args[j] = deps->at(i+j);
375 }
376 write_dependency_to(log(), dept, stride, args);
377 }
378 }
379 }
380
381 void Dependencies::write_dependency_to(CompileLog* log,
382 DepType dept,
383 int nargs, oop args[],
384 klassOop witness) {
385 if (log == NULL) {
386 return;
387 }
388 ciEnv* env = ciEnv::current();
389 ciObject* ciargs[max_arg_count];
390 assert(nargs <= max_arg_count, "oob");
391 for (int j = 0; j < nargs; j++) {
392 ciargs[j] = env->get_object(args[j]);
393 }
394 Dependencies::write_dependency_to(log, dept, nargs, ciargs, witness);
395 }
396
397 void Dependencies::write_dependency_to(CompileLog* log,
398 DepType dept,
399 int nargs, ciObject* args[],
400 klassOop witness) {
401 if (log == NULL) return;
402 assert(nargs <= max_arg_count, "oob");
403 int argids[max_arg_count];
404 int ctxkj = dep_context_arg(dept); // -1 if no context arg
405 int j;
406 for (j = 0; j < nargs; j++) {
407 argids[j] = log->identify(args[j]);
408 }
409 if (witness != NULL) {
410 log->begin_elem("dependency_failed");
411 } else {
412 log->begin_elem("dependency");
413 }
414 log->print(" type='%s'", dep_name(dept));
415 if (ctxkj >= 0) {
416 log->print(" ctxk='%d'", argids[ctxkj]);
417 }
418 // write remaining arguments, if any.
419 for (j = 0; j < nargs; j++) {
420 if (j == ctxkj) continue; // already logged
421 if (j == 1) {
422 log->print( " x='%d'", argids[j]);
423 } else {
424 log->print(" x%d='%d'", j, argids[j]);
425 }
426 }
427 if (witness != NULL) {
428 log->object("witness", witness);
429 log->stamp();
430 }
431 log->end_elem();
432 }
433
434 void Dependencies::write_dependency_to(xmlStream* xtty,
435 DepType dept,
436 int nargs, oop args[],
437 klassOop witness) {
438 if (xtty == NULL) return;
439 ttyLocker ttyl;
440 int ctxkj = dep_context_arg(dept); // -1 if no context arg
441 if (witness != NULL) {
442 xtty->begin_elem("dependency_failed");
443 } else {
444 xtty->begin_elem("dependency");
445 }
446 xtty->print(" type='%s'", dep_name(dept));
447 if (ctxkj >= 0) {
448 xtty->object("ctxk", args[ctxkj]);
449 }
450 // write remaining arguments, if any.
451 for (int j = 0; j < nargs; j++) {
452 if (j == ctxkj) continue; // already logged
453 if (j == 1) {
454 xtty->object("x", args[j]);
455 } else {
456 char xn[10]; sprintf(xn, "x%d", j);
457 xtty->object(xn, args[j]);
458 }
459 }
460 if (witness != NULL) {
461 xtty->object("witness", witness);
462 xtty->stamp();
463 }
464 xtty->end_elem();
465 }
466
467 void Dependencies::print_dependency(DepType dept, int nargs, oop args[],
468 klassOop witness) {
469 ResourceMark rm;
470 ttyLocker ttyl; // keep the following output all in one block
471 tty->print_cr("%s of type %s",
472 (witness == NULL)? "Dependency": "Failed dependency",
473 dep_name(dept));
474 // print arguments
475 int ctxkj = dep_context_arg(dept); // -1 if no context arg
476 for (int j = 0; j < nargs; j++) {
477 oop arg = args[j];
478 bool put_star = false;
479 if (arg == NULL) continue;
480 const char* what;
481 if (j == ctxkj) {
482 what = "context";
483 put_star = !Dependencies::is_concrete_klass((klassOop)arg);
484 } else if (arg->is_method()) {
485 what = "method ";
486 put_star = !Dependencies::is_concrete_method((methodOop)arg);
487 } else if (arg->is_klass()) {
488 what = "class ";
489 } else {
490 what = "object ";
491 }
492 tty->print(" %s = %s", what, (put_star? "*": ""));
493 if (arg->is_klass())
494 tty->print("%s", Klass::cast((klassOop)arg)->external_name());
495 else
496 arg->print_value();
497 tty->cr();
498 }
499 if (witness != NULL) {
500 bool put_star = !Dependencies::is_concrete_klass(witness);
501 tty->print_cr(" witness = %s%s",
502 (put_star? "*": ""),
503 Klass::cast(witness)->external_name());
504 }
505 }
506
507 void Dependencies::DepStream::log_dependency(klassOop witness) {
508 if (_deps == NULL && xtty == NULL) return; // fast cutout for runtime
509 int nargs = argument_count();
510 oop args[max_arg_count];
511 for (int j = 0; j < nargs; j++) {
512 args[j] = argument(j);
513 }
514 if (_deps != NULL && _deps->log() != NULL) {
515 Dependencies::write_dependency_to(_deps->log(),
516 type(), nargs, args, witness);
517 } else {
518 Dependencies::write_dependency_to(xtty,
519 type(), nargs, args, witness);
520 }
521 }
522
523 void Dependencies::DepStream::print_dependency(klassOop witness, bool verbose) {
524 int nargs = argument_count();
525 oop args[max_arg_count];
526 for (int j = 0; j < nargs; j++) {
527 args[j] = argument(j);
528 }
529 Dependencies::print_dependency(type(), nargs, args, witness);
530 if (verbose) {
531 if (_code != NULL) {
532 tty->print(" code: ");
533 _code->print_value_on(tty);
534 tty->cr();
535 }
536 }
537 }
538
539
540 /// Dependency stream support (decodes dependencies from an nmethod):
541
542 #ifdef ASSERT
543 void Dependencies::DepStream::initial_asserts(size_t byte_limit) {
544 assert(must_be_in_vm(), "raw oops here");
545 _byte_limit = byte_limit;
546 _type = (DepType)(end_marker-1); // defeat "already at end" assert
547 assert((_code!=NULL) + (_deps!=NULL) == 1, "one or t'other");
548 }
549 #endif //ASSERT
550
551 bool Dependencies::DepStream::next() {
552 assert(_type != end_marker, "already at end");
553 if (_bytes.position() == 0 && _code != NULL
554 && _code->dependencies_size() == 0) {
555 // Method has no dependencies at all.
556 return false;
557 }
558 int code_byte = (_bytes.read_byte() & 0xFF);
559 if (code_byte == end_marker) {
560 DEBUG_ONLY(_type = end_marker);
561 return false;
562 } else {
563 int ctxk_bit = (code_byte & Dependencies::default_context_type_bit);
564 code_byte -= ctxk_bit;
565 DepType dept = (DepType)code_byte;
566 _type = dept;
567 guarantee((dept - FIRST_TYPE) < (TYPE_LIMIT - FIRST_TYPE),
568 "bad dependency type tag");
569 int stride = _dep_args[dept];
570 assert(stride == dep_args(dept), "sanity");
571 int skipj = -1;
572 if (ctxk_bit != 0) {
573 skipj = 0; // currently the only context argument is at zero
574 assert(skipj == dep_context_arg(dept), "zero arg always ctxk");
575 }
576 for (int j = 0; j < stride; j++) {
577 _xi[j] = (j == skipj)? 0: _bytes.read_int();
578 }
579 DEBUG_ONLY(_xi[stride] = -1); // help detect overruns
580 return true;
581 }
582 }
583
584 inline oop Dependencies::DepStream::recorded_oop_at(int i) {
585 return (_code != NULL)
586 ? _code->oop_at(i)
587 : JNIHandles::resolve(_deps->oop_recorder()->handle_at(i));
588 }
589
590 oop Dependencies::DepStream::argument(int i) {
591 return recorded_oop_at(argument_index(i));
592 }
593
594 klassOop Dependencies::DepStream::context_type() {
595 assert(must_be_in_vm(), "raw oops here");
596 int ctxkj = dep_context_arg(_type); // -1 if no context arg
597 if (ctxkj < 0) {
598 return NULL; // for example, evol_method
599 } else {
600 oop k = recorded_oop_at(_xi[ctxkj]);
601 if (k != NULL) { // context type was not compressed away
602 assert(k->is_klass(), "type check");
603 return (klassOop) k;
604 } else { // recompute "default" context type
605 return ctxk_encoded_as_null(_type, recorded_oop_at(_xi[ctxkj+1]));
606 }
607 }
608 }
609
610 /// Checking dependencies:
611
612 // This hierarchy walker inspects subtypes of a given type,
613 // trying to find a "bad" class which breaks a dependency.
614 // Such a class is called a "witness" to the broken dependency.
615 // While searching around, we ignore "participants", which
616 // are already known to the dependency.
617 class ClassHierarchyWalker {
618 public:
619 enum { PARTICIPANT_LIMIT = 3 };
620
621 private:
622 // optional method descriptor to check for:
623 symbolOop _name;
624 symbolOop _signature;
625
626 // special classes which are not allowed to be witnesses:
627 klassOop _participants[PARTICIPANT_LIMIT+1];
628 int _num_participants;
629
630 // cache of method lookups
631 methodOop _found_methods[PARTICIPANT_LIMIT+1];
632
633 // if non-zero, tells how many witnesses to convert to participants
634 int _record_witnesses;
635
636 void initialize(klassOop participant) {
637 _record_witnesses = 0;
638 _participants[0] = participant;
639 _found_methods[0] = NULL;
640 _num_participants = 0;
641 if (participant != NULL) {
642 // Terminating NULL.
643 _participants[1] = NULL;
644 _found_methods[1] = NULL;
645 _num_participants = 1;
646 }
647 }
648
649 void initialize_from_method(methodOop m) {
650 assert(m != NULL && m->is_method(), "sanity");
651 _name = m->name();
652 _signature = m->signature();
653 }
654
655 public:
656 // The walker is initialized to recognize certain methods and/or types
657 // as friendly participants.
658 ClassHierarchyWalker(klassOop participant, methodOop m) {
659 initialize_from_method(m);
660 initialize(participant);
661 }
662 ClassHierarchyWalker(methodOop m) {
663 initialize_from_method(m);
664 initialize(NULL);
665 }
666 ClassHierarchyWalker(klassOop participant = NULL) {
667 _name = NULL;
668 _signature = NULL;
669 initialize(participant);
670 }
671
672 // This is common code for two searches: One for concrete subtypes,
673 // the other for concrete method implementations and overrides.
674 bool doing_subtype_search() {
675 return _name == NULL;
676 }
677
678 int num_participants() { return _num_participants; }
679 klassOop participant(int n) {
680 assert((uint)n <= (uint)_num_participants, "oob");
681 return _participants[n];
682 }
683
684 // Note: If n==num_participants, returns NULL.
685 methodOop found_method(int n) {
686 assert((uint)n <= (uint)_num_participants, "oob");
687 methodOop fm = _found_methods[n];
688 assert(n == _num_participants || fm != NULL, "proper usage");
689 assert(fm == NULL || fm->method_holder() == _participants[n], "sanity");
690 return fm;
691 }
692
693 #ifdef ASSERT
694 // Assert that m is inherited into ctxk, without intervening overrides.
695 // (May return true even if this is not true, in corner cases where we punt.)
696 bool check_method_context(klassOop ctxk, methodOop m) {
697 if (m->method_holder() == ctxk)
698 return true; // Quick win.
699 if (m->is_private())
700 return false; // Quick lose. Should not happen.
701 if (!(m->is_public() || m->is_protected()))
702 // The override story is complex when packages get involved.
703 return true; // Must punt the assertion to true.
704 Klass* k = Klass::cast(ctxk);
705 methodOop lm = k->lookup_method(m->name(), m->signature());
706 if (lm == NULL && k->oop_is_instance()) {
707 // It might be an abstract interface method, devoid of mirandas.
708 lm = ((instanceKlass*)k)->lookup_method_in_all_interfaces(m->name(),
709 m->signature());
710 }
711 if (lm == m)
712 // Method m is inherited into ctxk.
713 return true;
714 if (lm != NULL) {
715 if (!(lm->is_public() || lm->is_protected()))
716 // Method is [package-]private, so the override story is complex.
717 return true; // Must punt the assertion to true.
718 if ( !Dependencies::is_concrete_method(lm)
719 && !Dependencies::is_concrete_method(m)
720 && Klass::cast(lm->method_holder())->is_subtype_of(m->method_holder()))
721 // Method m is overridden by lm, but both are non-concrete.
722 return true;
723 }
724 ResourceMark rm;
725 tty->print_cr("Dependency method not found in the associated context:");
726 tty->print_cr(" context = %s", Klass::cast(ctxk)->external_name());
727 tty->print( " method = "); m->print_short_name(tty); tty->cr();
728 if (lm != NULL) {
729 tty->print( " found = "); lm->print_short_name(tty); tty->cr();
730 }
731 return false;
732 }
733 #endif
734
735 void add_participant(klassOop participant) {
736 assert(_num_participants + _record_witnesses < PARTICIPANT_LIMIT, "oob");
737 int np = _num_participants++;
738 _participants[np] = participant;
739 _participants[np+1] = NULL;
740 _found_methods[np+1] = NULL;
741 }
742
743 void record_witnesses(int add) {
744 if (add > PARTICIPANT_LIMIT) add = PARTICIPANT_LIMIT;
745 assert(_num_participants + add < PARTICIPANT_LIMIT, "oob");
746 _record_witnesses = add;
747 }
748
749 bool is_witness(klassOop k) {
750 if (doing_subtype_search()) {
751 return Dependencies::is_concrete_klass(k);
752 } else {
753 methodOop m = instanceKlass::cast(k)->find_method(_name, _signature);
754 if (m == NULL || !Dependencies::is_concrete_method(m)) return false;
755 _found_methods[_num_participants] = m;
756 // Note: If add_participant(k) is called,
757 // the method m will already be memoized for it.
758 return true;
759 }
760 }
761
762 bool is_participant(klassOop k) {
763 if (k == _participants[0]) {
764 return true;
765 } else if (_num_participants <= 1) {
766 return false;
767 } else {
768 return in_list(k, &_participants[1]);
769 }
770 }
771 bool ignore_witness(klassOop witness) {
772 if (_record_witnesses == 0) {
773 return false;
774 } else {
775 --_record_witnesses;
776 add_participant(witness);
777 return true;
778 }
779 }
780 static bool in_list(klassOop x, klassOop* list) {
781 for (int i = 0; ; i++) {
782 klassOop y = list[i];
783 if (y == NULL) break;
784 if (y == x) return true;
785 }
786 return false; // not in list
787 }
788
789 private:
790 // the actual search method:
791 klassOop find_witness_anywhere(klassOop context_type,
792 bool participants_hide_witnesses,
793 bool top_level_call = true);
794 // the spot-checking version:
795 klassOop find_witness_in(DepChange& changes,
796 klassOop context_type,
797 bool participants_hide_witnesses);
798 public:
799 klassOop find_witness_subtype(klassOop context_type, DepChange* changes = NULL) {
800 assert(doing_subtype_search(), "must set up a subtype search");
801 // When looking for unexpected concrete types,
802 // do not look beneath expected ones.
803 const bool participants_hide_witnesses = true;
804 // CX > CC > C' is OK, even if C' is new.
805 // CX > { CC, C' } is not OK if C' is new, and C' is the witness.
806 if (changes != NULL) {
807 return find_witness_in(*changes, context_type, participants_hide_witnesses);
808 } else {
809 return find_witness_anywhere(context_type, participants_hide_witnesses);
810 }
811 }
812 klassOop find_witness_definer(klassOop context_type, DepChange* changes = NULL) {
813 assert(!doing_subtype_search(), "must set up a method definer search");
814 // When looking for unexpected concrete methods,
815 // look beneath expected ones, to see if there are overrides.
816 const bool participants_hide_witnesses = true;
817 // CX.m > CC.m > C'.m is not OK, if C'.m is new, and C' is the witness.
818 if (changes != NULL) {
819 return find_witness_in(*changes, context_type, !participants_hide_witnesses);
820 } else {
821 return find_witness_anywhere(context_type, !participants_hide_witnesses);
822 }
823 }
824 };
825
826 #ifndef PRODUCT
827 static int deps_find_witness_calls = 0;
828 static int deps_find_witness_steps = 0;
829 static int deps_find_witness_recursions = 0;
830 static int deps_find_witness_singles = 0;
831 static int deps_find_witness_print = 0; // set to -1 to force a final print
832 static bool count_find_witness_calls() {
833 if (TraceDependencies || LogCompilation) {
834 int pcount = deps_find_witness_print + 1;
835 bool final_stats = (pcount == 0);
836 bool initial_call = (pcount == 1);
837 bool occasional_print = ((pcount & ((1<<10) - 1)) == 0);
838 if (pcount < 0) pcount = 1; // crude overflow protection
839 deps_find_witness_print = pcount;
840 if (VerifyDependencies && initial_call) {
841 tty->print_cr("Warning: TraceDependencies results may be inflated by VerifyDependencies");
842 }
843 if (occasional_print || final_stats) {
844 // Every now and then dump a little info about dependency searching.
845 if (xtty != NULL) {
846 ttyLocker ttyl;
847 xtty->elem("deps_find_witness calls='%d' steps='%d' recursions='%d' singles='%d'",
848 deps_find_witness_calls,
849 deps_find_witness_steps,
850 deps_find_witness_recursions,
851 deps_find_witness_singles);
852 }
853 if (final_stats || (TraceDependencies && WizardMode)) {
854 ttyLocker ttyl;
855 tty->print_cr("Dependency check (find_witness) "
856 "calls=%d, steps=%d (avg=%.1f), recursions=%d, singles=%d",
857 deps_find_witness_calls,
858 deps_find_witness_steps,
859 (double)deps_find_witness_steps / deps_find_witness_calls,
860 deps_find_witness_recursions,
861 deps_find_witness_singles);
862 }
863 }
864 return true;
865 }
866 return false;
867 }
868 #else
869 #define count_find_witness_calls() (0)
870 #endif //PRODUCT
871
872
873 klassOop ClassHierarchyWalker::find_witness_in(DepChange& changes,
874 klassOop context_type,
875 bool participants_hide_witnesses) {
876 assert(changes.involves_context(context_type), "irrelevant dependency");
877 klassOop new_type = changes.new_type();
878
879 count_find_witness_calls();
880 NOT_PRODUCT(deps_find_witness_singles++);
881
882 // Current thread must be in VM (not native mode, as in CI):
883 assert(must_be_in_vm(), "raw oops here");
884 // Must not move the class hierarchy during this check:
885 assert_locked_or_safepoint(Compile_lock);
886
887 int nof_impls = instanceKlass::cast(context_type)->nof_implementors();
888 if (nof_impls > 1) {
889 // Avoid this case: *I.m > { A.m, C }; B.m > C
890 // %%% Until this is fixed more systematically, bail out.
891 // See corresponding comment in find_witness_anywhere.
892 return context_type;
893 }
894
895 assert(!is_participant(new_type), "only old classes are participants");
896 if (participants_hide_witnesses) {
897 // If the new type is a subtype of a participant, we are done.
898 for (int i = 0; i < num_participants(); i++) {
899 klassOop part = participant(i);
900 if (part == NULL) continue;
901 assert(changes.involves_context(part) == Klass::cast(new_type)->is_subtype_of(part),
902 "correct marking of participants, b/c new_type is unique");
903 if (changes.involves_context(part)) {
904 // new guy is protected from this check by previous participant
905 return NULL;
906 }
907 }
908 }
909
910 if (is_witness(new_type) &&
911 !ignore_witness(new_type)) {
912 return new_type;
913 }
914
915 return NULL;
916 }
917
918
919 // Walk hierarchy under a context type, looking for unexpected types.
920 // Do not report participant types, and recursively walk beneath
921 // them only if participants_hide_witnesses is false.
922 // If top_level_call is false, skip testing the context type,
923 // because the caller has already considered it.
924 klassOop ClassHierarchyWalker::find_witness_anywhere(klassOop context_type,
925 bool participants_hide_witnesses,
926 bool top_level_call) {
927 // Current thread must be in VM (not native mode, as in CI):
928 assert(must_be_in_vm(), "raw oops here");
929 // Must not move the class hierarchy during this check:
930 assert_locked_or_safepoint(Compile_lock);
931
932 bool do_counts = count_find_witness_calls();
933
934 // Check the root of the sub-hierarchy first.
935 if (top_level_call) {
936 if (do_counts) {
937 NOT_PRODUCT(deps_find_witness_calls++);
938 NOT_PRODUCT(deps_find_witness_steps++);
939 }
940 if (is_participant(context_type)) {
941 if (participants_hide_witnesses) return NULL;
942 // else fall through to search loop...
943 } else if (is_witness(context_type) && !ignore_witness(context_type)) {
944 // The context is an abstract class or interface, to start with.
945 return context_type;
946 }
947 }
948
949 // Now we must check each implementor and each subclass.
950 // Use a short worklist to avoid blowing the stack.
951 // Each worklist entry is a *chain* of subklass siblings to process.
952 const int CHAINMAX = 100; // >= 1 + instanceKlass::implementors_limit
953 Klass* chains[CHAINMAX];
954 int chaini = 0; // index into worklist
955 Klass* chain; // scratch variable
956 #define ADD_SUBCLASS_CHAIN(k) { \
957 assert(chaini < CHAINMAX, "oob"); \
958 chain = instanceKlass::cast(k)->subklass(); \
959 if (chain != NULL) chains[chaini++] = chain; }
960
961 // Look for non-abstract subclasses.
962 // (Note: Interfaces do not have subclasses.)
963 ADD_SUBCLASS_CHAIN(context_type);
964
965 // If it is an interface, search its direct implementors.
966 // (Their subclasses are additional indirect implementors.
967 // See instanceKlass::add_implementor.)
968 // (Note: nof_implementors is always zero for non-interfaces.)
969 int nof_impls = instanceKlass::cast(context_type)->nof_implementors();
970 if (nof_impls > 1) {
971 // Avoid this case: *I.m > { A.m, C }; B.m > C
972 // Here, I.m has 2 concrete implementations, but m appears unique
973 // as A.m, because the search misses B.m when checking C.
974 // The inherited method B.m was getting missed by the walker
975 // when interface 'I' was the starting point.
976 // %%% Until this is fixed more systematically, bail out.
977 // (Old CHA had the same limitation.)
978 return context_type;
979 }
980 for (int i = 0; i < nof_impls; i++) {
981 klassOop impl = instanceKlass::cast(context_type)->implementor(i);
982 if (impl == NULL) {
983 // implementors array overflowed => no exact info.
984 return context_type; // report an inexact witness to this sad affair
985 }
986 if (do_counts)
987 { NOT_PRODUCT(deps_find_witness_steps++); }
988 if (is_participant(impl)) {
989 if (participants_hide_witnesses) continue;
990 // else fall through to process this guy's subclasses
991 } else if (is_witness(impl) && !ignore_witness(impl)) {
992 return impl;
993 }
994 ADD_SUBCLASS_CHAIN(impl);
995 }
996
997 // Recursively process each non-trivial sibling chain.
998 while (chaini > 0) {
999 Klass* chain = chains[--chaini];
1000 for (Klass* subk = chain; subk != NULL; subk = subk->next_sibling()) {
1001 klassOop sub = subk->as_klassOop();
1002 if (do_counts) { NOT_PRODUCT(deps_find_witness_steps++); }
1003 if (is_participant(sub)) {
1004 if (participants_hide_witnesses) continue;
1005 // else fall through to process this guy's subclasses
1006 } else if (is_witness(sub) && !ignore_witness(sub)) {
1007 return sub;
1008 }
1009 if (chaini < (VerifyDependencies? 2: CHAINMAX)) {
1010 // Fast path. (Partially disabled if VerifyDependencies.)
1011 ADD_SUBCLASS_CHAIN(sub);
1012 } else {
1013 // Worklist overflow. Do a recursive call. Should be rare.
1014 // The recursive call will have its own worklist, of course.
1015 // (Note that sub has already been tested, so that there is
1016 // no need for the recursive call to re-test. That's handy,
1017 // since the recursive call sees sub as the context_type.)
1018 if (do_counts) { NOT_PRODUCT(deps_find_witness_recursions++); }
1019 klassOop witness = find_witness_anywhere(sub,
1020 participants_hide_witnesses,
1021 /*top_level_call=*/ false);
1022 if (witness != NULL) return witness;
1023 }
1024 }
1025 }
1026
1027 // No witness found. The dependency remains unbroken.
1028 return NULL;
1029 #undef ADD_SUBCLASS_CHAIN
1030 }
1031
1032
1033 bool Dependencies::is_concrete_klass(klassOop k) {
1034 if (Klass::cast(k)->is_abstract()) return false;
1035 // %%% We could treat classes which are concrete but
1036 // have not yet been instantiated as virtually abstract.
1037 // This would require a deoptimization barrier on first instantiation.
1038 //if (k->is_not_instantiated()) return false;
1039 return true;
1040 }
1041
1042 bool Dependencies::is_concrete_method(methodOop m) {
1043 if (m->is_abstract()) return false;
1044 // %%% We could treat unexecuted methods as virtually abstract also.
1045 // This would require a deoptimization barrier on first execution.
1046 return !m->is_abstract();
1047 }
1048
1049
1050 Klass* Dependencies::find_finalizable_subclass(Klass* k) {
1051 if (k->is_interface()) return NULL;
1052 if (k->has_finalizer()) return k;
1053 k = k->subklass();
1054 while (k != NULL) {
1055 Klass* result = find_finalizable_subclass(k);
1056 if (result != NULL) return result;
1057 k = k->next_sibling();
1058 }
1059 return NULL;
1060 }
1061
1062
1063 bool Dependencies::is_concrete_klass(ciInstanceKlass* k) {
1064 if (k->is_abstract()) return false;
1065 // We could return also false if k does not yet appear to be
1066 // instantiated, if the VM version supports this distinction also.
1067 //if (k->is_not_instantiated()) return false;
1068 return true;
1069 }
1070
1071 bool Dependencies::is_concrete_method(ciMethod* m) {
1072 // Statics are irrelevant to virtual call sites.
1073 if (m->is_static()) return false;
1074
1075 // We could return also false if m does not yet appear to be
1076 // executed, if the VM version supports this distinction also.
1077 return !m->is_abstract();
1078 }
1079
1080
1081 bool Dependencies::has_finalizable_subclass(ciInstanceKlass* k) {
1082 return k->has_finalizable_subclass();
1083 }
1084
1085
1086 // Any use of the contents (bytecodes) of a method must be
1087 // marked by an "evol_method" dependency, if those contents
1088 // can change. (Note: A method is always dependent on itself.)
1089 klassOop Dependencies::check_evol_method(methodOop m) {
1090 assert(must_be_in_vm(), "raw oops here");
1091 // Did somebody do a JVMTI RedefineClasses while our backs were turned?
1092 // Or is there a now a breakpoint?
1093 // (Assumes compiled code cannot handle bkpts; change if UseFastBreakpoints.)
1094 if (m->is_old()
1095 || m->number_of_breakpoints() > 0) {
1096 return m->method_holder();
1097 } else {
1098 return NULL;
1099 }
1100 }
1101
1102 // This is a strong assertion: It is that the given type
1103 // has no subtypes whatever. It is most useful for
1104 // optimizing checks on reflected types or on array types.
1105 // (Checks on types which are derived from real instances
1106 // can be optimized more strongly than this, because we
1107 // know that the checked type comes from a concrete type,
1108 // and therefore we can disregard abstract types.)
1109 klassOop Dependencies::check_leaf_type(klassOop ctxk) {
1110 assert(must_be_in_vm(), "raw oops here");
1111 assert_locked_or_safepoint(Compile_lock);
1112 instanceKlass* ctx = instanceKlass::cast(ctxk);
1113 Klass* sub = ctx->subklass();
1114 if (sub != NULL) {
1115 return sub->as_klassOop();
1116 } else if (ctx->nof_implementors() != 0) {
1117 // if it is an interface, it must be unimplemented
1118 // (if it is not an interface, nof_implementors is always zero)
1119 klassOop impl = ctx->implementor(0);
1120 return (impl != NULL)? impl: ctxk;
1121 } else {
1122 return NULL;
1123 }
1124 }
1125
1126 // Test the assertion that conck is the only concrete subtype* of ctxk.
1127 // The type conck itself is allowed to have have further concrete subtypes.
1128 // This allows the compiler to narrow occurrences of ctxk by conck,
1129 // when dealing with the types of actual instances.
1130 klassOop Dependencies::check_abstract_with_unique_concrete_subtype(klassOop ctxk,
1131 klassOop conck,
1132 DepChange* changes) {
1133 ClassHierarchyWalker wf(conck);
1134 return wf.find_witness_subtype(ctxk, changes);
1135 }
1136
1137 // If a non-concrete class has no concrete subtypes, it is not (yet)
1138 // instantiatable. This can allow the compiler to make some paths go
1139 // dead, if they are gated by a test of the type.
1140 klassOop Dependencies::check_abstract_with_no_concrete_subtype(klassOop ctxk,
1141 DepChange* changes) {
1142 // Find any concrete subtype, with no participants:
1143 ClassHierarchyWalker wf;
1144 return wf.find_witness_subtype(ctxk, changes);
1145 }
1146
1147
1148 // If a concrete class has no concrete subtypes, it can always be
1149 // exactly typed. This allows the use of a cheaper type test.
1150 klassOop Dependencies::check_concrete_with_no_concrete_subtype(klassOop ctxk,
1151 DepChange* changes) {
1152 // Find any concrete subtype, with only the ctxk as participant:
1153 ClassHierarchyWalker wf(ctxk);
1154 return wf.find_witness_subtype(ctxk, changes);
1155 }
1156
1157
1158 // Find the unique concrete proper subtype of ctxk, or NULL if there
1159 // is more than one concrete proper subtype. If there are no concrete
1160 // proper subtypes, return ctxk itself, whether it is concrete or not.
1161 // The returned subtype is allowed to have have further concrete subtypes.
1162 // That is, return CC1 for CX > CC1 > CC2, but NULL for CX > { CC1, CC2 }.
1163 klassOop Dependencies::find_unique_concrete_subtype(klassOop ctxk) {
1164 ClassHierarchyWalker wf(ctxk); // Ignore ctxk when walking.
1165 wf.record_witnesses(1); // Record one other witness when walking.
1166 klassOop wit = wf.find_witness_subtype(ctxk);
1167 if (wit != NULL) return NULL; // Too many witnesses.
1168 klassOop conck = wf.participant(0);
1169 if (conck == NULL) {
1170 #ifndef PRODUCT
1171 // Make sure the dependency mechanism will pass this discovery:
1172 if (VerifyDependencies) {
1173 // Turn off dependency tracing while actually testing deps.
1174 FlagSetting fs(TraceDependencies, false);
1175 if (!Dependencies::is_concrete_klass(ctxk)) {
1176 guarantee(NULL ==
1177 (void *)check_abstract_with_no_concrete_subtype(ctxk),
1178 "verify dep.");
1179 } else {
1180 guarantee(NULL ==
1181 (void *)check_concrete_with_no_concrete_subtype(ctxk),
1182 "verify dep.");
1183 }
1184 }
1185 #endif //PRODUCT
1186 return ctxk; // Return ctxk as a flag for "no subtypes".
1187 } else {
1188 #ifndef PRODUCT
1189 // Make sure the dependency mechanism will pass this discovery:
1190 if (VerifyDependencies) {
1191 // Turn off dependency tracing while actually testing deps.
1192 FlagSetting fs(TraceDependencies, false);
1193 if (!Dependencies::is_concrete_klass(ctxk)) {
1194 guarantee(NULL == (void *)
1195 check_abstract_with_unique_concrete_subtype(ctxk, conck),
1196 "verify dep.");
1197 }
1198 }
1199 #endif //PRODUCT
1200 return conck;
1201 }
1202 }
1203
1204 // Test the assertion that the k[12] are the only concrete subtypes of ctxk,
1205 // except possibly for further subtypes of k[12] themselves.
1206 // The context type must be abstract. The types k1 and k2 are themselves
1207 // allowed to have further concrete subtypes.
1208 klassOop Dependencies::check_abstract_with_exclusive_concrete_subtypes(
1209 klassOop ctxk,
1210 klassOop k1,
1211 klassOop k2,
1212 DepChange* changes) {
1213 ClassHierarchyWalker wf;
1214 wf.add_participant(k1);
1215 wf.add_participant(k2);
1216 return wf.find_witness_subtype(ctxk, changes);
1217 }
1218
1219 // Search ctxk for concrete implementations. If there are klen or fewer,
1220 // pack them into the given array and return the number.
1221 // Otherwise, return -1, meaning the given array would overflow.
1222 // (Note that a return of 0 means there are exactly no concrete subtypes.)
1223 // In this search, if ctxk is concrete, it will be reported alone.
1224 // For any type CC reported, no proper subtypes of CC will be reported.
1225 int Dependencies::find_exclusive_concrete_subtypes(klassOop ctxk,
1226 int klen,
1227 klassOop karray[]) {
1228 ClassHierarchyWalker wf;
1229 wf.record_witnesses(klen);
1230 klassOop wit = wf.find_witness_subtype(ctxk);
1231 if (wit != NULL) return -1; // Too many witnesses.
1232 int num = wf.num_participants();
1233 assert(num <= klen, "oob");
1234 // Pack the result array with the good news.
1235 for (int i = 0; i < num; i++)
1236 karray[i] = wf.participant(i);
1237 #ifndef PRODUCT
1238 // Make sure the dependency mechanism will pass this discovery:
1239 if (VerifyDependencies) {
1240 // Turn off dependency tracing while actually testing deps.
1241 FlagSetting fs(TraceDependencies, false);
1242 switch (Dependencies::is_concrete_klass(ctxk)? -1: num) {
1243 case -1: // ctxk was itself concrete
1244 guarantee(num == 1 && karray[0] == ctxk, "verify dep.");
1245 break;
1246 case 0:
1247 guarantee(NULL == (void *)check_abstract_with_no_concrete_subtype(ctxk),
1248 "verify dep.");
1249 break;
1250 case 1:
1251 guarantee(NULL == (void *)
1252 check_abstract_with_unique_concrete_subtype(ctxk, karray[0]),
1253 "verify dep.");
1254 break;
1255 case 2:
1256 guarantee(NULL == (void *)
1257 check_abstract_with_exclusive_concrete_subtypes(ctxk,
1258 karray[0],
1259 karray[1]),
1260 "verify dep.");
1261 break;
1262 default:
1263 ShouldNotReachHere(); // klen > 2 yet supported
1264 }
1265 }
1266 #endif //PRODUCT
1267 return num;
1268 }
1269
1270 // If a class (or interface) has a unique concrete method uniqm, return NULL.
1271 // Otherwise, return a class that contains an interfering method.
1272 klassOop Dependencies::check_unique_concrete_method(klassOop ctxk, methodOop uniqm,
1273 DepChange* changes) {
1274 // Here is a missing optimization: If uniqm->is_final(),
1275 // we don't really need to search beneath it for overrides.
1276 // This is probably not important, since we don't use dependencies
1277 // to track final methods. (They can't be "definalized".)
1278 ClassHierarchyWalker wf(uniqm->method_holder(), uniqm);
1279 return wf.find_witness_definer(ctxk, changes);
1280 }
1281
1282 // Find the set of all non-abstract methods under ctxk that match m.
1283 // (The method m must be defined or inherited in ctxk.)
1284 // Include m itself in the set, unless it is abstract.
1285 // If this set has exactly one element, return that element.
1286 methodOop Dependencies::find_unique_concrete_method(klassOop ctxk, methodOop m) {
1287 ClassHierarchyWalker wf(m);
1288 assert(wf.check_method_context(ctxk, m), "proper context");
1289 wf.record_witnesses(1);
1290 klassOop wit = wf.find_witness_definer(ctxk);
1291 if (wit != NULL) return NULL; // Too many witnesses.
1292 methodOop fm = wf.found_method(0); // Will be NULL if num_parts == 0.
1293 if (Dependencies::is_concrete_method(m)) {
1294 if (fm == NULL) {
1295 // It turns out that m was always the only implementation.
1296 fm = m;
1297 } else if (fm != m) {
1298 // Two conflicting implementations after all.
1299 // (This can happen if m is inherited into ctxk and fm overrides it.)
1300 return NULL;
1301 }
1302 }
1303 #ifndef PRODUCT
1304 // Make sure the dependency mechanism will pass this discovery:
1305 if (VerifyDependencies && fm != NULL) {
1306 guarantee(NULL == (void *)check_unique_concrete_method(ctxk, fm),
1307 "verify dep.");
1308 }
1309 #endif //PRODUCT
1310 return fm;
1311 }
1312
1313 klassOop Dependencies::check_exclusive_concrete_methods(klassOop ctxk,
1314 methodOop m1,
1315 methodOop m2,
1316 DepChange* changes) {
1317 ClassHierarchyWalker wf(m1);
1318 wf.add_participant(m1->method_holder());
1319 wf.add_participant(m2->method_holder());
1320 return wf.find_witness_definer(ctxk, changes);
1321 }
1322
1323 // Find the set of all non-abstract methods under ctxk that match m[0].
1324 // (The method m[0] must be defined or inherited in ctxk.)
1325 // Include m itself in the set, unless it is abstract.
1326 // Fill the given array m[0..(mlen-1)] with this set, and return the length.
1327 // (The length may be zero if no concrete methods are found anywhere.)
1328 // If there are too many concrete methods to fit in marray, return -1.
1329 int Dependencies::find_exclusive_concrete_methods(klassOop ctxk,
1330 int mlen,
1331 methodOop marray[]) {
1332 methodOop m0 = marray[0];
1333 ClassHierarchyWalker wf(m0);
1334 assert(wf.check_method_context(ctxk, m0), "proper context");
1335 wf.record_witnesses(mlen);
1336 bool participants_hide_witnesses = true;
1337 klassOop wit = wf.find_witness_definer(ctxk);
1338 if (wit != NULL) return -1; // Too many witnesses.
1339 int num = wf.num_participants();
1340 assert(num <= mlen, "oob");
1341 // Keep track of whether m is also part of the result set.
1342 int mfill = 0;
1343 assert(marray[mfill] == m0, "sanity");
1344 if (Dependencies::is_concrete_method(m0))
1345 mfill++; // keep m0 as marray[0], the first result
1346 for (int i = 0; i < num; i++) {
1347 methodOop fm = wf.found_method(i);
1348 if (fm == m0) continue; // Already put this guy in the list.
1349 if (mfill == mlen) {
1350 return -1; // Oops. Too many methods after all!
1351 }
1352 marray[mfill++] = fm;
1353 }
1354 #ifndef PRODUCT
1355 // Make sure the dependency mechanism will pass this discovery:
1356 if (VerifyDependencies) {
1357 // Turn off dependency tracing while actually testing deps.
1358 FlagSetting fs(TraceDependencies, false);
1359 switch (mfill) {
1360 case 1:
1361 guarantee(NULL == (void *)check_unique_concrete_method(ctxk, marray[0]),
1362 "verify dep.");
1363 break;
1364 case 2:
1365 guarantee(NULL == (void *)
1366 check_exclusive_concrete_methods(ctxk, marray[0], marray[1]),
1367 "verify dep.");
1368 break;
1369 default:
1370 ShouldNotReachHere(); // mlen > 2 yet supported
1371 }
1372 }
1373 #endif //PRODUCT
1374 return mfill;
1375 }
1376
1377
1378 klassOop Dependencies::check_has_no_finalizable_subclasses(klassOop ctxk, DepChange* changes) {
1379 Klass* search_at = ctxk->klass_part();
1380 if (changes != NULL)
1381 search_at = changes->new_type()->klass_part(); // just look at the new bit
1382 Klass* result = find_finalizable_subclass(search_at);
1383 if (result == NULL) {
1384 return NULL;
1385 }
1386 return result->as_klassOop();
1387 }
1388
1389
1390 klassOop Dependencies::DepStream::check_dependency_impl(DepChange* changes) {
1391 assert_locked_or_safepoint(Compile_lock);
1392
1393 klassOop witness = NULL;
1394 switch (type()) {
1395 case evol_method:
1396 witness = check_evol_method(method_argument(0));
1397 break;
1398 case leaf_type:
1399 witness = check_leaf_type(context_type());
1400 break;
1401 case abstract_with_unique_concrete_subtype:
1402 witness = check_abstract_with_unique_concrete_subtype(context_type(),
1403 type_argument(1),
1404 changes);
1405 break;
1406 case abstract_with_no_concrete_subtype:
1407 witness = check_abstract_with_no_concrete_subtype(context_type(),
1408 changes);
1409 break;
1410 case concrete_with_no_concrete_subtype:
1411 witness = check_concrete_with_no_concrete_subtype(context_type(),
1412 changes);
1413 break;
1414 case unique_concrete_method:
1415 witness = check_unique_concrete_method(context_type(),
1416 method_argument(1),
1417 changes);
1418 break;
1419 case abstract_with_exclusive_concrete_subtypes_2:
1420 witness = check_abstract_with_exclusive_concrete_subtypes(context_type(),
1421 type_argument(1),
1422 type_argument(2),
1423 changes);
1424 break;
1425 case exclusive_concrete_methods_2:
1426 witness = check_exclusive_concrete_methods(context_type(),
1427 method_argument(1),
1428 method_argument(2),
1429 changes);
1430 break;
1431 case no_finalizable_subclasses:
1432 witness = check_has_no_finalizable_subclasses(context_type(),
1433 changes);
1434 break;
1435 default:
1436 witness = NULL;
1437 ShouldNotReachHere();
1438 break;
1439 }
1440 if (witness != NULL) {
1441 if (TraceDependencies) {
1442 print_dependency(witness, /*verbose=*/ true);
1443 }
1444 // The following is a no-op unless logging is enabled:
1445 log_dependency(witness);
1446 }
1447 return witness;
1448 }
1449
1450
1451 klassOop Dependencies::DepStream::spot_check_dependency_at(DepChange& changes) {
1452 if (!changes.involves_context(context_type()))
1453 // irrelevant dependency; skip it
1454 return NULL;
1455
1456 return check_dependency_impl(&changes);
1457 }
1458
1459
1460 void DepChange::initialize() {
1461 // entire transaction must be under this lock:
1462 assert_lock_strong(Compile_lock);
1463
1464 // Mark all dependee and all its superclasses
1465 // Mark transitive interfaces
1466 for (ContextStream str(*this); str.next(); ) {
1467 klassOop d = str.klass();
1468 assert(!instanceKlass::cast(d)->is_marked_dependent(), "checking");
1469 instanceKlass::cast(d)->set_is_marked_dependent(true);
1470 }
1471 }
1472
1473 DepChange::~DepChange() {
1474 // Unmark all dependee and all its superclasses
1475 // Unmark transitive interfaces
1476 for (ContextStream str(*this); str.next(); ) {
1477 klassOop d = str.klass();
1478 instanceKlass::cast(d)->set_is_marked_dependent(false);
1479 }
1480 }
1481
1482 bool DepChange::involves_context(klassOop k) {
1483 if (k == NULL || !Klass::cast(k)->oop_is_instance()) {
1484 return false;
1485 }
1486 instanceKlass* ik = instanceKlass::cast(k);
1487 bool is_contained = ik->is_marked_dependent();
1488 assert(is_contained == Klass::cast(new_type())->is_subtype_of(k),
1489 "correct marking of potential context types");
1490 return is_contained;
1491 }
1492
1493 bool DepChange::ContextStream::next() {
1494 switch (_change_type) {
1495 case Start_Klass: // initial state; _klass is the new type
1496 _ti_base = instanceKlass::cast(_klass)->transitive_interfaces();
1497 _ti_index = 0;
1498 _change_type = Change_new_type;
1499 return true;
1500 case Change_new_type:
1501 // fall through:
1502 _change_type = Change_new_sub;
1503 case Change_new_sub:
1504 // 6598190: brackets workaround Sun Studio C++ compiler bug 6629277
1505 {
1506 _klass = instanceKlass::cast(_klass)->super();
1507 if (_klass != NULL) {
1508 return true;
1509 }
1510 }
1511 // else set up _ti_limit and fall through:
1512 _ti_limit = (_ti_base == NULL) ? 0 : _ti_base->length();
1513 _change_type = Change_new_impl;
1514 case Change_new_impl:
1515 if (_ti_index < _ti_limit) {
1516 _klass = klassOop( _ti_base->obj_at(_ti_index++) );
1517 return true;
1518 }
1519 // fall through:
1520 _change_type = NO_CHANGE; // iterator is exhausted
1521 case NO_CHANGE:
1522 break;
1523 default:
1524 ShouldNotReachHere();
1525 }
1526 return false;
1527 }
1528
1529 void DepChange::print() {
1530 int nsup = 0, nint = 0;
1531 for (ContextStream str(*this); str.next(); ) {
1532 klassOop k = str.klass();
1533 switch (str.change_type()) {
1534 case Change_new_type:
1535 tty->print_cr(" dependee = %s", instanceKlass::cast(k)->external_name());
1536 break;
1537 case Change_new_sub:
1538 if (!WizardMode) {
1539 ++nsup;
1540 } else {
1541 tty->print_cr(" context super = %s", instanceKlass::cast(k)->external_name());
1542 }
1543 break;
1544 case Change_new_impl:
1545 if (!WizardMode) {
1546 ++nint;
1547 } else {
1548 tty->print_cr(" context interface = %s", instanceKlass::cast(k)->external_name());
1549 }
1550 break;
1551 }
1552 }
1553 if (nsup + nint != 0) {
1554 tty->print_cr(" context supers = %d, interfaces = %d", nsup, nint);
1555 }
1556 }
1557
1558 #ifndef PRODUCT
1559 void Dependencies::print_statistics() {
1560 if (deps_find_witness_print != 0) {
1561 // Call one final time, to flush out the data.
1562 deps_find_witness_print = -1;
1563 count_find_witness_calls();
1564 }
1565 }
1566 #endif