1 /*
2 * Copyright (c) 2005, 2010, 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 "ci/ciArrayKlass.hpp"
27 #include "ci/ciEnv.hpp"
28 #include "ci/ciKlass.hpp"
29 #include "ci/ciMethod.hpp"
30 #include "code/dependencies.hpp"
31 #include "compiler/compileLog.hpp"
32 #include "oops/oop.inline.hpp"
33 #include "runtime/handles.inline.hpp"
34 #include "utilities/copy.hpp"
35
36
37 #ifdef ASSERT
38 static bool must_be_in_vm() {
39 Thread* thread = Thread::current();
40 if (thread->is_Java_thread())
41 return ((JavaThread*)thread)->thread_state() == _thread_in_vm;
42 else
43 return true; //something like this: thread->is_VM_thread();
44 }
45 #endif //ASSERT
46
47 void Dependencies::initialize(ciEnv* env) {
48 Arena* arena = env->arena();
49 _oop_recorder = env->oop_recorder();
50 _log = env->log();
51 _dep_seen = new(arena) GrowableArray<int>(arena, 500, 0, 0);
52 DEBUG_ONLY(_deps[end_marker] = NULL);
53 for (int i = (int)FIRST_TYPE; i < (int)TYPE_LIMIT; i++) {
54 _deps[i] = new(arena) GrowableArray<ciObject*>(arena, 10, 0, 0);
55 }
56 _content_bytes = NULL;
57 _size_in_bytes = (size_t)-1;
58
59 assert(TYPE_LIMIT <= (1<<LG2_TYPE_LIMIT), "sanity");
60 }
61
62 void Dependencies::assert_evol_method(ciMethod* m) {
63 assert_common_1(evol_method, m);
64 }
65
66 void Dependencies::assert_leaf_type(ciKlass* ctxk) {
67 if (ctxk->is_array_klass()) {
68 // As a special case, support this assertion on an array type,
69 // which reduces to an assertion on its element type.
70 // Note that this cannot be done with assertions that
71 // relate to concreteness or abstractness.
72 ciType* elemt = ctxk->as_array_klass()->base_element_type();
73 if (!elemt->is_instance_klass()) return; // Ex: int[][]
74 ctxk = elemt->as_instance_klass();
75 //if (ctxk->is_final()) return; // Ex: String[][]
76 }
77 check_ctxk(ctxk);
78 assert_common_1(leaf_type, ctxk);
79 }
80
81 void Dependencies::assert_abstract_with_unique_concrete_subtype(ciKlass* ctxk, ciKlass* conck) {
82 check_ctxk_abstract(ctxk);
83 assert_common_2(abstract_with_unique_concrete_subtype, ctxk, conck);
84 }
85
86 void Dependencies::assert_abstract_with_no_concrete_subtype(ciKlass* ctxk) {
87 check_ctxk_abstract(ctxk);
88 assert_common_1(abstract_with_no_concrete_subtype, ctxk);
89 }
90
91 void Dependencies::assert_concrete_with_no_concrete_subtype(ciKlass* ctxk) {
92 check_ctxk_concrete(ctxk);
93 assert_common_1(concrete_with_no_concrete_subtype, ctxk);
94 }
95
96 void Dependencies::assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm) {
97 check_ctxk(ctxk);
98 assert_common_2(unique_concrete_method, ctxk, uniqm);
99 }
100
101 void Dependencies::assert_abstract_with_exclusive_concrete_subtypes(ciKlass* ctxk, ciKlass* k1, ciKlass* k2) {
102 check_ctxk(ctxk);
103 assert_common_3(abstract_with_exclusive_concrete_subtypes_2, ctxk, k1, k2);
104 }
105
106 void Dependencies::assert_exclusive_concrete_methods(ciKlass* ctxk, ciMethod* m1, ciMethod* m2) {
107 check_ctxk(ctxk);
108 assert_common_3(exclusive_concrete_methods_2, ctxk, m1, m2);
109 }
110
111 void Dependencies::assert_has_no_finalizable_subclasses(ciKlass* ctxk) {
112 check_ctxk(ctxk);
113 assert_common_1(no_finalizable_subclasses, ctxk);
114 }
115
116 // Helper function. If we are adding a new dep. under ctxk2,
117 // try to find an old dep. under a broader* ctxk1. If there is
118 //
119 bool Dependencies::maybe_merge_ctxk(GrowableArray<ciObject*>* deps,
120 int ctxk_i, ciKlass* ctxk2) {
121 ciKlass* ctxk1 = deps->at(ctxk_i)->as_klass();
122 if (ctxk2->is_subtype_of(ctxk1)) {
123 return true; // success, and no need to change
124 } else if (ctxk1->is_subtype_of(ctxk2)) {
125 // new context class fully subsumes previous one
126 deps->at_put(ctxk_i, ctxk2);
127 return true;
128 } else {
129 return false;
130 }
131 }
132
133 void Dependencies::assert_common_1(Dependencies::DepType dept, ciObject* x) {
134 assert(dep_args(dept) == 1, "sanity");
135 log_dependency(dept, x);
136 GrowableArray<ciObject*>* deps = _deps[dept];
137
138 // see if the same (or a similar) dep is already recorded
139 if (note_dep_seen(dept, x)) {
140 assert(deps->find(x) >= 0, "sanity");
141 } else {
142 deps->append(x);
143 }
144 }
145
146 void Dependencies::assert_common_2(Dependencies::DepType dept,
147 ciKlass* ctxk, ciObject* x) {
148 assert(dep_context_arg(dept) == 0, "sanity");
149 assert(dep_args(dept) == 2, "sanity");
150 log_dependency(dept, ctxk, x);
151 GrowableArray<ciObject*>* deps = _deps[dept];
152
153 // see if the same (or a similar) dep is already recorded
154 if (note_dep_seen(dept, x)) {
155 // look in this bucket for redundant assertions
156 const int stride = 2;
157 for (int i = deps->length(); (i -= stride) >= 0; ) {
158 ciObject* x1 = deps->at(i+1);
159 if (x == x1) { // same subject; check the context
160 if (maybe_merge_ctxk(deps, i+0, ctxk)) {
161 return;
162 }
163 }
164 }
165 }
166
167 // append the assertion in the correct bucket:
168 deps->append(ctxk);
169 deps->append(x);
170 }
171
172 void Dependencies::assert_common_3(Dependencies::DepType dept,
173 ciKlass* ctxk, ciObject* x, ciObject* x2) {
174 assert(dep_context_arg(dept) == 0, "sanity");
175 assert(dep_args(dept) == 3, "sanity");
176 log_dependency(dept, ctxk, x, x2);
177 GrowableArray<ciObject*>* deps = _deps[dept];
178
179 // try to normalize an unordered pair:
180 bool swap = false;
181 switch (dept) {
182 case abstract_with_exclusive_concrete_subtypes_2:
183 swap = (x->ident() > x2->ident() && x != ctxk);
184 break;
185 case exclusive_concrete_methods_2:
186 swap = (x->ident() > x2->ident() && x->as_method()->holder() != ctxk);
187 break;
188 }
189 if (swap) { ciObject* t = x; x = x2; x2 = t; }
190
191 // see if the same (or a similar) dep is already recorded
192 if (note_dep_seen(dept, x) && note_dep_seen(dept, x2)) {
193 // look in this bucket for redundant assertions
194 const int stride = 3;
195 for (int i = deps->length(); (i -= stride) >= 0; ) {
196 ciObject* y = deps->at(i+1);
197 ciObject* y2 = deps->at(i+2);
198 if (x == y && x2 == y2) { // same subjects; check the context
199 if (maybe_merge_ctxk(deps, i+0, ctxk)) {
200 return;
201 }
202 }
203 }
204 }
205 // append the assertion in the correct bucket:
206 deps->append(ctxk);
207 deps->append(x);
208 deps->append(x2);
209 }
210
211 /// Support for encoding dependencies into an nmethod:
212
213 void Dependencies::copy_to(nmethod* nm) {
214 address beg = nm->dependencies_begin();
215 address end = nm->dependencies_end();
216 guarantee(end - beg >= (ptrdiff_t) size_in_bytes(), "bad sizing");
217 Copy::disjoint_words((HeapWord*) content_bytes(),
218 (HeapWord*) beg,
219 size_in_bytes() / sizeof(HeapWord));
220 assert(size_in_bytes() % sizeof(HeapWord) == 0, "copy by words");
221 }
222
223 static int sort_dep(ciObject** p1, ciObject** p2, int narg) {
224 for (int i = 0; i < narg; i++) {
225 int diff = p1[i]->ident() - p2[i]->ident();
226 if (diff != 0) return diff;
227 }
228 return 0;
229 }
230 static int sort_dep_arg_1(ciObject** p1, ciObject** p2)
231 { return sort_dep(p1, p2, 1); }
232 static int sort_dep_arg_2(ciObject** p1, ciObject** p2)
233 { return sort_dep(p1, p2, 2); }
234 static int sort_dep_arg_3(ciObject** p1, ciObject** p2)
235 { return sort_dep(p1, p2, 3); }
236
237 void Dependencies::sort_all_deps() {
238 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
239 DepType dept = (DepType)deptv;
240 GrowableArray<ciObject*>* deps = _deps[dept];
241 if (deps->length() <= 1) continue;
242 switch (dep_args(dept)) {
243 case 1: deps->sort(sort_dep_arg_1, 1); break;
244 case 2: deps->sort(sort_dep_arg_2, 2); break;
245 case 3: deps->sort(sort_dep_arg_3, 3); break;
246 default: ShouldNotReachHere();
247 }
248 }
249 }
250
251 size_t Dependencies::estimate_size_in_bytes() {
252 size_t est_size = 100;
253 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
254 DepType dept = (DepType)deptv;
255 GrowableArray<ciObject*>* deps = _deps[dept];
256 est_size += deps->length()*2; // tags and argument(s)
257 }
258 return est_size;
259 }
260
261 ciKlass* Dependencies::ctxk_encoded_as_null(DepType dept, ciObject* x) {
262 switch (dept) {
263 case abstract_with_exclusive_concrete_subtypes_2:
264 return x->as_klass();
265 case unique_concrete_method:
266 case exclusive_concrete_methods_2:
267 return x->as_method()->holder();
268 }
269 return NULL; // let NULL be NULL
270 }
271
272 klassOop Dependencies::ctxk_encoded_as_null(DepType dept, oop x) {
273 assert(must_be_in_vm(), "raw oops here");
274 switch (dept) {
275 case abstract_with_exclusive_concrete_subtypes_2:
276 assert(x->is_klass(), "sanity");
277 return (klassOop) x;
278 case unique_concrete_method:
279 case exclusive_concrete_methods_2:
280 assert(x->is_method(), "sanity");
281 return ((methodOop)x)->method_holder();
282 }
283 return NULL; // let NULL be NULL
284 }
285
286 void Dependencies::encode_content_bytes() {
287 sort_all_deps();
288
289 // cast is safe, no deps can overflow INT_MAX
290 CompressedWriteStream bytes((int)estimate_size_in_bytes());
291
292 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
293 DepType dept = (DepType)deptv;
294 GrowableArray<ciObject*>* deps = _deps[dept];
295 if (deps->length() == 0) continue;
296 int stride = dep_args(dept);
297 int ctxkj = dep_context_arg(dept); // -1 if no context arg
298 assert(stride > 0, "sanity");
299 for (int i = 0; i < deps->length(); i += stride) {
300 jbyte code_byte = (jbyte)dept;
301 int skipj = -1;
302 if (ctxkj >= 0 && ctxkj+1 < stride) {
303 ciKlass* ctxk = deps->at(i+ctxkj+0)->as_klass();
304 ciObject* x = deps->at(i+ctxkj+1); // following argument
305 if (ctxk == ctxk_encoded_as_null(dept, x)) {
306 skipj = ctxkj; // we win: maybe one less oop to keep track of
307 code_byte |= default_context_type_bit;
308 }
309 }
310 bytes.write_byte(code_byte);
311 for (int j = 0; j < stride; j++) {
312 if (j == skipj) continue;
313 bytes.write_int(_oop_recorder->find_index(deps->at(i+j)->constant_encoding()));
314 }
315 }
316 }
317
318 // write a sentinel byte to mark the end
319 bytes.write_byte(end_marker);
320
321 // round it out to a word boundary
322 while (bytes.position() % sizeof(HeapWord) != 0) {
323 bytes.write_byte(end_marker);
324 }
325
326 // check whether the dept byte encoding really works
327 assert((jbyte)default_context_type_bit != 0, "byte overflow");
328
329 _content_bytes = bytes.buffer();
330 _size_in_bytes = bytes.position();
331 }
332
333
334 const char* Dependencies::_dep_name[TYPE_LIMIT] = {
335 "end_marker",
336 "evol_method",
337 "leaf_type",
338 "abstract_with_unique_concrete_subtype",
339 "abstract_with_no_concrete_subtype",
340 "concrete_with_no_concrete_subtype",
341 "unique_concrete_method",
342 "abstract_with_exclusive_concrete_subtypes_2",
343 "exclusive_concrete_methods_2",
344 "no_finalizable_subclasses"
345 };
346
347 int Dependencies::_dep_args[TYPE_LIMIT] = {
348 -1,// end_marker
349 1, // evol_method m
350 1, // leaf_type ctxk
351 2, // abstract_with_unique_concrete_subtype ctxk, k
352 1, // abstract_with_no_concrete_subtype ctxk
353 1, // concrete_with_no_concrete_subtype ctxk
354 2, // unique_concrete_method ctxk, m
355 3, // unique_concrete_subtypes_2 ctxk, k1, k2
356 3, // unique_concrete_methods_2 ctxk, m1, m2
357 1 // no_finalizable_subclasses ctxk
358 };
359
360 const char* Dependencies::dep_name(Dependencies::DepType dept) {
361 if (!dept_in_mask(dept, all_types)) return "?bad-dep?";
362 return _dep_name[dept];
363 }
364
365 int Dependencies::dep_args(Dependencies::DepType dept) {
366 if (!dept_in_mask(dept, all_types)) return -1;
367 return _dep_args[dept];
368 }
369
370 // for the sake of the compiler log, print out current dependencies:
371 void Dependencies::log_all_dependencies() {
372 if (log() == NULL) return;
373 ciObject* args[max_arg_count];
374 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
375 DepType dept = (DepType)deptv;
376 GrowableArray<ciObject*>* deps = _deps[dept];
377 if (deps->length() == 0) continue;
378 int stride = dep_args(dept);
379 for (int i = 0; i < deps->length(); i += stride) {
380 for (int j = 0; j < stride; j++) {
381 // flush out the identities before printing
382 args[j] = deps->at(i+j);
383 }
384 write_dependency_to(log(), dept, stride, args);
385 }
386 }
387 }
388
389 void Dependencies::write_dependency_to(CompileLog* log,
390 DepType dept,
391 int nargs, oop args[],
392 klassOop witness) {
393 if (log == NULL) {
394 return;
395 }
396 ciEnv* env = ciEnv::current();
397 ciObject* ciargs[max_arg_count];
398 assert(nargs <= max_arg_count, "oob");
399 for (int j = 0; j < nargs; j++) {
400 ciargs[j] = env->get_object(args[j]);
401 }
402 Dependencies::write_dependency_to(log, dept, nargs, ciargs, witness);
403 }
404
405 void Dependencies::write_dependency_to(CompileLog* log,
406 DepType dept,
407 int nargs, ciObject* args[],
408 klassOop witness) {
409 if (log == NULL) return;
410 assert(nargs <= max_arg_count, "oob");
411 int argids[max_arg_count];
412 int ctxkj = dep_context_arg(dept); // -1 if no context arg
413 int j;
414 for (j = 0; j < nargs; j++) {
415 argids[j] = log->identify(args[j]);
416 }
417 if (witness != NULL) {
418 log->begin_elem("dependency_failed");
419 } else {
420 log->begin_elem("dependency");
421 }
422 log->print(" type='%s'", dep_name(dept));
423 if (ctxkj >= 0) {
424 log->print(" ctxk='%d'", argids[ctxkj]);
425 }
426 // write remaining arguments, if any.
427 for (j = 0; j < nargs; j++) {
428 if (j == ctxkj) continue; // already logged
429 if (j == 1) {
430 log->print( " x='%d'", argids[j]);
431 } else {
432 log->print(" x%d='%d'", j, argids[j]);
433 }
434 }
435 if (witness != NULL) {
436 log->object("witness", witness);
437 log->stamp();
438 }
439 log->end_elem();
440 }
441
442 void Dependencies::write_dependency_to(xmlStream* xtty,
443 DepType dept,
444 int nargs, oop args[],
445 klassOop witness) {
446 if (xtty == NULL) return;
447 ttyLocker ttyl;
448 int ctxkj = dep_context_arg(dept); // -1 if no context arg
449 if (witness != NULL) {
450 xtty->begin_elem("dependency_failed");
451 } else {
452 xtty->begin_elem("dependency");
453 }
454 xtty->print(" type='%s'", dep_name(dept));
455 if (ctxkj >= 0) {
456 xtty->object("ctxk", args[ctxkj]);
457 }
458 // write remaining arguments, if any.
459 for (int j = 0; j < nargs; j++) {
460 if (j == ctxkj) continue; // already logged
461 if (j == 1) {
462 xtty->object("x", args[j]);
463 } else {
464 char xn[10]; sprintf(xn, "x%d", j);
465 xtty->object(xn, args[j]);
466 }
467 }
468 if (witness != NULL) {
469 xtty->object("witness", witness);
470 xtty->stamp();
471 }
472 xtty->end_elem();
473 }
474
475 void Dependencies::print_dependency(DepType dept, int nargs, oop args[],
476 klassOop witness) {
477 ResourceMark rm;
478 ttyLocker ttyl; // keep the following output all in one block
479 tty->print_cr("%s of type %s",
480 (witness == NULL)? "Dependency": "Failed dependency",
481 dep_name(dept));
482 // print arguments
483 int ctxkj = dep_context_arg(dept); // -1 if no context arg
484 for (int j = 0; j < nargs; j++) {
485 oop arg = args[j];
486 bool put_star = false;
487 if (arg == NULL) continue;
488 const char* what;
489 if (j == ctxkj) {
490 what = "context";
491 put_star = !Dependencies::is_concrete_klass((klassOop)arg);
492 } else if (arg->is_method()) {
493 what = "method ";
494 put_star = !Dependencies::is_concrete_method((methodOop)arg);
495 } else if (arg->is_klass()) {
496 what = "class ";
497 } else {
498 what = "object ";
499 }
500 tty->print(" %s = %s", what, (put_star? "*": ""));
501 if (arg->is_klass())
502 tty->print("%s", Klass::cast((klassOop)arg)->external_name());
503 else
504 arg->print_value();
505 tty->cr();
506 }
507 if (witness != NULL) {
508 bool put_star = !Dependencies::is_concrete_klass(witness);
509 tty->print_cr(" witness = %s%s",
510 (put_star? "*": ""),
511 Klass::cast(witness)->external_name());
512 }
513 }
514
515 void Dependencies::DepStream::log_dependency(klassOop witness) {
516 if (_deps == NULL && xtty == NULL) return; // fast cutout for runtime
517 int nargs = argument_count();
518 oop args[max_arg_count];
519 for (int j = 0; j < nargs; j++) {
520 args[j] = argument(j);
521 }
522 if (_deps != NULL && _deps->log() != NULL) {
523 Dependencies::write_dependency_to(_deps->log(),
524 type(), nargs, args, witness);
525 } else {
526 Dependencies::write_dependency_to(xtty,
527 type(), nargs, args, witness);
528 }
529 }
530
531 void Dependencies::DepStream::print_dependency(klassOop witness, bool verbose) {
532 int nargs = argument_count();
533 oop args[max_arg_count];
534 for (int j = 0; j < nargs; j++) {
535 args[j] = argument(j);
536 }
537 Dependencies::print_dependency(type(), nargs, args, witness);
538 if (verbose) {
539 if (_code != NULL) {
540 tty->print(" code: ");
541 _code->print_value_on(tty);
542 tty->cr();
543 }
544 }
545 }
546
547
548 /// Dependency stream support (decodes dependencies from an nmethod):
549
550 #ifdef ASSERT
551 void Dependencies::DepStream::initial_asserts(size_t byte_limit) {
552 assert(must_be_in_vm(), "raw oops here");
553 _byte_limit = byte_limit;
554 _type = (DepType)(end_marker-1); // defeat "already at end" assert
555 assert((_code!=NULL) + (_deps!=NULL) == 1, "one or t'other");
556 }
557 #endif //ASSERT
558
559 bool Dependencies::DepStream::next() {
560 assert(_type != end_marker, "already at end");
561 if (_bytes.position() == 0 && _code != NULL
562 && _code->dependencies_size() == 0) {
563 // Method has no dependencies at all.
564 return false;
565 }
566 int code_byte = (_bytes.read_byte() & 0xFF);
567 if (code_byte == end_marker) {
568 DEBUG_ONLY(_type = end_marker);
569 return false;
570 } else {
571 int ctxk_bit = (code_byte & Dependencies::default_context_type_bit);
572 code_byte -= ctxk_bit;
573 DepType dept = (DepType)code_byte;
574 _type = dept;
575 guarantee((dept - FIRST_TYPE) < (TYPE_LIMIT - FIRST_TYPE),
576 "bad dependency type tag");
577 int stride = _dep_args[dept];
578 assert(stride == dep_args(dept), "sanity");
579 int skipj = -1;
580 if (ctxk_bit != 0) {
581 skipj = 0; // currently the only context argument is at zero
582 assert(skipj == dep_context_arg(dept), "zero arg always ctxk");
583 }
584 for (int j = 0; j < stride; j++) {
585 _xi[j] = (j == skipj)? 0: _bytes.read_int();
586 }
587 DEBUG_ONLY(_xi[stride] = -1); // help detect overruns
588 return true;
589 }
590 }
591
592 inline oop Dependencies::DepStream::recorded_oop_at(int i) {
593 return (_code != NULL)
594 ? _code->oop_at(i)
595 : JNIHandles::resolve(_deps->oop_recorder()->handle_at(i));
596 }
597
598 oop Dependencies::DepStream::argument(int i) {
599 return recorded_oop_at(argument_index(i));
600 }
601
602 klassOop Dependencies::DepStream::context_type() {
603 assert(must_be_in_vm(), "raw oops here");
604 int ctxkj = dep_context_arg(_type); // -1 if no context arg
605 if (ctxkj < 0) {
606 return NULL; // for example, evol_method
607 } else {
608 oop k = recorded_oop_at(_xi[ctxkj]);
609 if (k != NULL) { // context type was not compressed away
610 assert(k->is_klass(), "type check");
611 return (klassOop) k;
612 } else { // recompute "default" context type
613 return ctxk_encoded_as_null(_type, recorded_oop_at(_xi[ctxkj+1]));
614 }
615 }
616 }
617
618 /// Checking dependencies:
619
620 // This hierarchy walker inspects subtypes of a given type,
621 // trying to find a "bad" class which breaks a dependency.
622 // Such a class is called a "witness" to the broken dependency.
623 // While searching around, we ignore "participants", which
624 // are already known to the dependency.
625 class ClassHierarchyWalker {
626 public:
627 enum { PARTICIPANT_LIMIT = 3 };
628
629 private:
630 // optional method descriptor to check for:
631 symbolOop _name;
632 symbolOop _signature;
633
634 // special classes which are not allowed to be witnesses:
635 klassOop _participants[PARTICIPANT_LIMIT+1];
636 int _num_participants;
637
638 // cache of method lookups
639 methodOop _found_methods[PARTICIPANT_LIMIT+1];
640
641 // if non-zero, tells how many witnesses to convert to participants
642 int _record_witnesses;
643
644 void initialize(klassOop participant) {
645 _record_witnesses = 0;
646 _participants[0] = participant;
647 _found_methods[0] = NULL;
648 _num_participants = 0;
649 if (participant != NULL) {
650 // Terminating NULL.
651 _participants[1] = NULL;
652 _found_methods[1] = NULL;
653 _num_participants = 1;
654 }
655 }
656
657 void initialize_from_method(methodOop m) {
658 assert(m != NULL && m->is_method(), "sanity");
659 _name = m->name();
660 _signature = m->signature();
661 }
662
663 public:
664 // The walker is initialized to recognize certain methods and/or types
665 // as friendly participants.
666 ClassHierarchyWalker(klassOop participant, methodOop m) {
667 initialize_from_method(m);
668 initialize(participant);
669 }
670 ClassHierarchyWalker(methodOop m) {
671 initialize_from_method(m);
672 initialize(NULL);
673 }
674 ClassHierarchyWalker(klassOop participant = NULL) {
675 _name = NULL;
676 _signature = NULL;
677 initialize(participant);
678 }
679
680 // This is common code for two searches: One for concrete subtypes,
681 // the other for concrete method implementations and overrides.
682 bool doing_subtype_search() {
683 return _name == NULL;
684 }
685
686 int num_participants() { return _num_participants; }
687 klassOop participant(int n) {
688 assert((uint)n <= (uint)_num_participants, "oob");
689 return _participants[n];
690 }
691
692 // Note: If n==num_participants, returns NULL.
693 methodOop found_method(int n) {
694 assert((uint)n <= (uint)_num_participants, "oob");
695 methodOop fm = _found_methods[n];
696 assert(n == _num_participants || fm != NULL, "proper usage");
697 assert(fm == NULL || fm->method_holder() == _participants[n], "sanity");
698 return fm;
699 }
700
701 #ifdef ASSERT
702 // Assert that m is inherited into ctxk, without intervening overrides.
703 // (May return true even if this is not true, in corner cases where we punt.)
704 bool check_method_context(klassOop ctxk, methodOop m) {
705 if (m->method_holder() == ctxk)
706 return true; // Quick win.
707 if (m->is_private())
708 return false; // Quick lose. Should not happen.
709 if (!(m->is_public() || m->is_protected()))
710 // The override story is complex when packages get involved.
711 return true; // Must punt the assertion to true.
712 Klass* k = Klass::cast(ctxk);
713 methodOop lm = k->lookup_method(m->name(), m->signature());
714 if (lm == NULL && k->oop_is_instance()) {
715 // It might be an abstract interface method, devoid of mirandas.
716 lm = ((instanceKlass*)k)->lookup_method_in_all_interfaces(m->name(),
717 m->signature());
718 }
719 if (lm == m)
720 // Method m is inherited into ctxk.
721 return true;
722 if (lm != NULL) {
723 if (!(lm->is_public() || lm->is_protected()))
724 // Method is [package-]private, so the override story is complex.
725 return true; // Must punt the assertion to true.
726 if ( !Dependencies::is_concrete_method(lm)
727 && !Dependencies::is_concrete_method(m)
728 && Klass::cast(lm->method_holder())->is_subtype_of(m->method_holder()))
729 // Method m is overridden by lm, but both are non-concrete.
730 return true;
731 }
732 ResourceMark rm;
733 tty->print_cr("Dependency method not found in the associated context:");
734 tty->print_cr(" context = %s", Klass::cast(ctxk)->external_name());
735 tty->print( " method = "); m->print_short_name(tty); tty->cr();
736 if (lm != NULL) {
737 tty->print( " found = "); lm->print_short_name(tty); tty->cr();
738 }
739 return false;
740 }
741 #endif
742
743 void add_participant(klassOop participant) {
744 assert(_num_participants + _record_witnesses < PARTICIPANT_LIMIT, "oob");
745 int np = _num_participants++;
746 _participants[np] = participant;
747 _participants[np+1] = NULL;
748 _found_methods[np+1] = NULL;
749 }
750
751 void record_witnesses(int add) {
752 if (add > PARTICIPANT_LIMIT) add = PARTICIPANT_LIMIT;
753 assert(_num_participants + add < PARTICIPANT_LIMIT, "oob");
754 _record_witnesses = add;
755 }
756
757 bool is_witness(klassOop k) {
758 if (doing_subtype_search()) {
759 return Dependencies::is_concrete_klass(k);
760 } else {
761 methodOop m = instanceKlass::cast(k)->find_method(_name, _signature);
762 if (m == NULL || !Dependencies::is_concrete_method(m)) return false;
763 _found_methods[_num_participants] = m;
764 // Note: If add_participant(k) is called,
765 // the method m will already be memoized for it.
766 return true;
767 }
768 }
769
770 bool is_participant(klassOop k) {
771 if (k == _participants[0]) {
772 return true;
773 } else if (_num_participants <= 1) {
774 return false;
775 } else {
776 return in_list(k, &_participants[1]);
777 }
778 }
779 bool ignore_witness(klassOop witness) {
780 if (_record_witnesses == 0) {
781 return false;
782 } else {
783 --_record_witnesses;
784 add_participant(witness);
785 return true;
786 }
787 }
788 static bool in_list(klassOop x, klassOop* list) {
789 for (int i = 0; ; i++) {
790 klassOop y = list[i];
791 if (y == NULL) break;
792 if (y == x) return true;
793 }
794 return false; // not in list
795 }
796
797 private:
798 // the actual search method:
799 klassOop find_witness_anywhere(klassOop context_type,
800 bool participants_hide_witnesses,
801 bool top_level_call = true);
802 // the spot-checking version:
803 klassOop find_witness_in(DepChange& changes,
804 klassOop context_type,
805 bool participants_hide_witnesses);
806 public:
807 klassOop find_witness_subtype(klassOop context_type, DepChange* changes = NULL) {
808 assert(doing_subtype_search(), "must set up a subtype search");
809 // When looking for unexpected concrete types,
810 // do not look beneath expected ones.
811 const bool participants_hide_witnesses = true;
812 // CX > CC > C' is OK, even if C' is new.
813 // CX > { CC, C' } is not OK if C' is new, and C' is the witness.
814 if (changes != NULL) {
815 return find_witness_in(*changes, context_type, participants_hide_witnesses);
816 } else {
817 return find_witness_anywhere(context_type, participants_hide_witnesses);
818 }
819 }
820 klassOop find_witness_definer(klassOop context_type, DepChange* changes = NULL) {
821 assert(!doing_subtype_search(), "must set up a method definer search");
822 // When looking for unexpected concrete methods,
823 // look beneath expected ones, to see if there are overrides.
824 const bool participants_hide_witnesses = true;
825 // CX.m > CC.m > C'.m is not OK, if C'.m is new, and C' is the witness.
826 if (changes != NULL) {
827 return find_witness_in(*changes, context_type, !participants_hide_witnesses);
828 } else {
829 return find_witness_anywhere(context_type, !participants_hide_witnesses);
830 }
831 }
832 };
833
834 #ifndef PRODUCT
835 static int deps_find_witness_calls = 0;
836 static int deps_find_witness_steps = 0;
837 static int deps_find_witness_recursions = 0;
838 static int deps_find_witness_singles = 0;
839 static int deps_find_witness_print = 0; // set to -1 to force a final print
840 static bool count_find_witness_calls() {
841 if (TraceDependencies || LogCompilation) {
842 int pcount = deps_find_witness_print + 1;
843 bool final_stats = (pcount == 0);
844 bool initial_call = (pcount == 1);
845 bool occasional_print = ((pcount & ((1<<10) - 1)) == 0);
846 if (pcount < 0) pcount = 1; // crude overflow protection
847 deps_find_witness_print = pcount;
848 if (VerifyDependencies && initial_call) {
849 tty->print_cr("Warning: TraceDependencies results may be inflated by VerifyDependencies");
850 }
851 if (occasional_print || final_stats) {
852 // Every now and then dump a little info about dependency searching.
853 if (xtty != NULL) {
854 ttyLocker ttyl;
855 xtty->elem("deps_find_witness calls='%d' steps='%d' recursions='%d' singles='%d'",
856 deps_find_witness_calls,
857 deps_find_witness_steps,
858 deps_find_witness_recursions,
859 deps_find_witness_singles);
860 }
861 if (final_stats || (TraceDependencies && WizardMode)) {
862 ttyLocker ttyl;
863 tty->print_cr("Dependency check (find_witness) "
864 "calls=%d, steps=%d (avg=%.1f), recursions=%d, singles=%d",
865 deps_find_witness_calls,
866 deps_find_witness_steps,
867 (double)deps_find_witness_steps / deps_find_witness_calls,
868 deps_find_witness_recursions,
869 deps_find_witness_singles);
870 }
871 }
872 return true;
873 }
874 return false;
875 }
876 #else
877 #define count_find_witness_calls() (0)
878 #endif //PRODUCT
879
880
881 klassOop ClassHierarchyWalker::find_witness_in(DepChange& changes,
882 klassOop context_type,
883 bool participants_hide_witnesses) {
884 assert(changes.involves_context(context_type), "irrelevant dependency");
885 klassOop new_type = changes.new_type();
886
887 count_find_witness_calls();
888 NOT_PRODUCT(deps_find_witness_singles++);
889
890 // Current thread must be in VM (not native mode, as in CI):
891 assert(must_be_in_vm(), "raw oops here");
892 // Must not move the class hierarchy during this check:
893 assert_locked_or_safepoint(Compile_lock);
894
895 int nof_impls = instanceKlass::cast(context_type)->nof_implementors();
896 if (nof_impls > 1) {
897 // Avoid this case: *I.m > { A.m, C }; B.m > C
898 // %%% Until this is fixed more systematically, bail out.
899 // See corresponding comment in find_witness_anywhere.
900 return context_type;
901 }
902
903 assert(!is_participant(new_type), "only old classes are participants");
904 if (participants_hide_witnesses) {
905 // If the new type is a subtype of a participant, we are done.
906 for (int i = 0; i < num_participants(); i++) {
907 klassOop part = participant(i);
908 if (part == NULL) continue;
909 assert(changes.involves_context(part) == Klass::cast(new_type)->is_subtype_of(part),
910 "correct marking of participants, b/c new_type is unique");
911 if (changes.involves_context(part)) {
912 // new guy is protected from this check by previous participant
913 return NULL;
914 }
915 }
916 }
917
918 if (is_witness(new_type) &&
919 !ignore_witness(new_type)) {
920 return new_type;
921 }
922
923 return NULL;
924 }
925
926
927 // Walk hierarchy under a context type, looking for unexpected types.
928 // Do not report participant types, and recursively walk beneath
929 // them only if participants_hide_witnesses is false.
930 // If top_level_call is false, skip testing the context type,
931 // because the caller has already considered it.
932 klassOop ClassHierarchyWalker::find_witness_anywhere(klassOop context_type,
933 bool participants_hide_witnesses,
934 bool top_level_call) {
935 // Current thread must be in VM (not native mode, as in CI):
936 assert(must_be_in_vm(), "raw oops here");
937 // Must not move the class hierarchy during this check:
938 assert_locked_or_safepoint(Compile_lock);
939
940 bool do_counts = count_find_witness_calls();
941
942 // Check the root of the sub-hierarchy first.
943 if (top_level_call) {
944 if (do_counts) {
945 NOT_PRODUCT(deps_find_witness_calls++);
946 NOT_PRODUCT(deps_find_witness_steps++);
947 }
948 if (is_participant(context_type)) {
949 if (participants_hide_witnesses) return NULL;
950 // else fall through to search loop...
951 } else if (is_witness(context_type) && !ignore_witness(context_type)) {
952 // The context is an abstract class or interface, to start with.
953 return context_type;
954 }
955 }
956
957 // Now we must check each implementor and each subclass.
958 // Use a short worklist to avoid blowing the stack.
959 // Each worklist entry is a *chain* of subklass siblings to process.
960 const int CHAINMAX = 100; // >= 1 + instanceKlass::implementors_limit
961 Klass* chains[CHAINMAX];
962 int chaini = 0; // index into worklist
963 Klass* chain; // scratch variable
964 #define ADD_SUBCLASS_CHAIN(k) { \
965 assert(chaini < CHAINMAX, "oob"); \
966 chain = instanceKlass::cast(k)->subklass(); \
967 if (chain != NULL) chains[chaini++] = chain; }
968
969 // Look for non-abstract subclasses.
970 // (Note: Interfaces do not have subclasses.)
971 ADD_SUBCLASS_CHAIN(context_type);
972
973 // If it is an interface, search its direct implementors.
974 // (Their subclasses are additional indirect implementors.
975 // See instanceKlass::add_implementor.)
976 // (Note: nof_implementors is always zero for non-interfaces.)
977 int nof_impls = instanceKlass::cast(context_type)->nof_implementors();
978 if (nof_impls > 1) {
979 // Avoid this case: *I.m > { A.m, C }; B.m > C
980 // Here, I.m has 2 concrete implementations, but m appears unique
981 // as A.m, because the search misses B.m when checking C.
982 // The inherited method B.m was getting missed by the walker
983 // when interface 'I' was the starting point.
984 // %%% Until this is fixed more systematically, bail out.
985 // (Old CHA had the same limitation.)
986 return context_type;
987 }
988 for (int i = 0; i < nof_impls; i++) {
989 klassOop impl = instanceKlass::cast(context_type)->implementor(i);
990 if (impl == NULL) {
991 // implementors array overflowed => no exact info.
992 return context_type; // report an inexact witness to this sad affair
993 }
994 if (do_counts)
995 { NOT_PRODUCT(deps_find_witness_steps++); }
996 if (is_participant(impl)) {
997 if (participants_hide_witnesses) continue;
998 // else fall through to process this guy's subclasses
999 } else if (is_witness(impl) && !ignore_witness(impl)) {
1000 return impl;
1001 }
1002 ADD_SUBCLASS_CHAIN(impl);
1003 }
1004
1005 // Recursively process each non-trivial sibling chain.
1006 while (chaini > 0) {
1007 Klass* chain = chains[--chaini];
1008 for (Klass* subk = chain; subk != NULL; subk = subk->next_sibling()) {
1009 klassOop sub = subk->as_klassOop();
1010 if (do_counts) { NOT_PRODUCT(deps_find_witness_steps++); }
1011 if (is_participant(sub)) {
1012 if (participants_hide_witnesses) continue;
1013 // else fall through to process this guy's subclasses
1014 } else if (is_witness(sub) && !ignore_witness(sub)) {
1015 return sub;
1016 }
1017 if (chaini < (VerifyDependencies? 2: CHAINMAX)) {
1018 // Fast path. (Partially disabled if VerifyDependencies.)
1019 ADD_SUBCLASS_CHAIN(sub);
1020 } else {
1021 // Worklist overflow. Do a recursive call. Should be rare.
1022 // The recursive call will have its own worklist, of course.
1023 // (Note that sub has already been tested, so that there is
1024 // no need for the recursive call to re-test. That's handy,
1025 // since the recursive call sees sub as the context_type.)
1026 if (do_counts) { NOT_PRODUCT(deps_find_witness_recursions++); }
1027 klassOop witness = find_witness_anywhere(sub,
1028 participants_hide_witnesses,
1029 /*top_level_call=*/ false);
1030 if (witness != NULL) return witness;
1031 }
1032 }
1033 }
1034
1035 // No witness found. The dependency remains unbroken.
1036 return NULL;
1037 #undef ADD_SUBCLASS_CHAIN
1038 }
1039
1040
1041 bool Dependencies::is_concrete_klass(klassOop k) {
1042 if (Klass::cast(k)->is_abstract()) return false;
1043 // %%% We could treat classes which are concrete but
1044 // have not yet been instantiated as virtually abstract.
1045 // This would require a deoptimization barrier on first instantiation.
1046 //if (k->is_not_instantiated()) return false;
1047 return true;
1048 }
1049
1050 bool Dependencies::is_concrete_method(methodOop m) {
1051 if (m->is_abstract()) return false;
1052 // %%% We could treat unexecuted methods as virtually abstract also.
1053 // This would require a deoptimization barrier on first execution.
1054 return !m->is_abstract();
1055 }
1056
1057
1058 Klass* Dependencies::find_finalizable_subclass(Klass* k) {
1059 if (k->is_interface()) return NULL;
1060 if (k->has_finalizer()) return k;
1061 k = k->subklass();
1062 while (k != NULL) {
1063 Klass* result = find_finalizable_subclass(k);
1064 if (result != NULL) return result;
1065 k = k->next_sibling();
1066 }
1067 return NULL;
1068 }
1069
1070
1071 bool Dependencies::is_concrete_klass(ciInstanceKlass* k) {
1072 if (k->is_abstract()) return false;
1073 // We could return also false if k does not yet appear to be
1074 // instantiated, if the VM version supports this distinction also.
1075 //if (k->is_not_instantiated()) return false;
1076 return true;
1077 }
1078
1079 bool Dependencies::is_concrete_method(ciMethod* m) {
1080 // Statics are irrelevant to virtual call sites.
1081 if (m->is_static()) return false;
1082
1083 // We could return also false if m does not yet appear to be
1084 // executed, if the VM version supports this distinction also.
1085 return !m->is_abstract();
1086 }
1087
1088
1089 bool Dependencies::has_finalizable_subclass(ciInstanceKlass* k) {
1090 return k->has_finalizable_subclass();
1091 }
1092
1093
1094 // Any use of the contents (bytecodes) of a method must be
1095 // marked by an "evol_method" dependency, if those contents
1096 // can change. (Note: A method is always dependent on itself.)
1097 klassOop Dependencies::check_evol_method(methodOop m) {
1098 assert(must_be_in_vm(), "raw oops here");
1099 // Did somebody do a JVMTI RedefineClasses while our backs were turned?
1100 // Or is there a now a breakpoint?
1101 // (Assumes compiled code cannot handle bkpts; change if UseFastBreakpoints.)
1102 if (m->is_old()
1103 || m->number_of_breakpoints() > 0) {
1104 return m->method_holder();
1105 } else {
1106 return NULL;
1107 }
1108 }
1109
1110 // This is a strong assertion: It is that the given type
1111 // has no subtypes whatever. It is most useful for
1112 // optimizing checks on reflected types or on array types.
1113 // (Checks on types which are derived from real instances
1114 // can be optimized more strongly than this, because we
1115 // know that the checked type comes from a concrete type,
1116 // and therefore we can disregard abstract types.)
1117 klassOop Dependencies::check_leaf_type(klassOop ctxk) {
1118 assert(must_be_in_vm(), "raw oops here");
1119 assert_locked_or_safepoint(Compile_lock);
1120 instanceKlass* ctx = instanceKlass::cast(ctxk);
1121 Klass* sub = ctx->subklass();
1122 if (sub != NULL) {
1123 return sub->as_klassOop();
1124 } else if (ctx->nof_implementors() != 0) {
1125 // if it is an interface, it must be unimplemented
1126 // (if it is not an interface, nof_implementors is always zero)
1127 klassOop impl = ctx->implementor(0);
1128 return (impl != NULL)? impl: ctxk;
1129 } else {
1130 return NULL;
1131 }
1132 }
1133
1134 // Test the assertion that conck is the only concrete subtype* of ctxk.
1135 // The type conck itself is allowed to have have further concrete subtypes.
1136 // This allows the compiler to narrow occurrences of ctxk by conck,
1137 // when dealing with the types of actual instances.
1138 klassOop Dependencies::check_abstract_with_unique_concrete_subtype(klassOop ctxk,
1139 klassOop conck,
1140 DepChange* changes) {
1141 ClassHierarchyWalker wf(conck);
1142 return wf.find_witness_subtype(ctxk, changes);
1143 }
1144
1145 // If a non-concrete class has no concrete subtypes, it is not (yet)
1146 // instantiatable. This can allow the compiler to make some paths go
1147 // dead, if they are gated by a test of the type.
1148 klassOop Dependencies::check_abstract_with_no_concrete_subtype(klassOop ctxk,
1149 DepChange* changes) {
1150 // Find any concrete subtype, with no participants:
1151 ClassHierarchyWalker wf;
1152 return wf.find_witness_subtype(ctxk, changes);
1153 }
1154
1155
1156 // If a concrete class has no concrete subtypes, it can always be
1157 // exactly typed. This allows the use of a cheaper type test.
1158 klassOop Dependencies::check_concrete_with_no_concrete_subtype(klassOop ctxk,
1159 DepChange* changes) {
1160 // Find any concrete subtype, with only the ctxk as participant:
1161 ClassHierarchyWalker wf(ctxk);
1162 return wf.find_witness_subtype(ctxk, changes);
1163 }
1164
1165
1166 // Find the unique concrete proper subtype of ctxk, or NULL if there
1167 // is more than one concrete proper subtype. If there are no concrete
1168 // proper subtypes, return ctxk itself, whether it is concrete or not.
1169 // The returned subtype is allowed to have have further concrete subtypes.
1170 // That is, return CC1 for CX > CC1 > CC2, but NULL for CX > { CC1, CC2 }.
1171 klassOop Dependencies::find_unique_concrete_subtype(klassOop ctxk) {
1172 ClassHierarchyWalker wf(ctxk); // Ignore ctxk when walking.
1173 wf.record_witnesses(1); // Record one other witness when walking.
1174 klassOop wit = wf.find_witness_subtype(ctxk);
1175 if (wit != NULL) return NULL; // Too many witnesses.
1176 klassOop conck = wf.participant(0);
1177 if (conck == NULL) {
1178 #ifndef PRODUCT
1179 // Make sure the dependency mechanism will pass this discovery:
1180 if (VerifyDependencies) {
1181 // Turn off dependency tracing while actually testing deps.
1182 FlagSetting fs(TraceDependencies, false);
1183 if (!Dependencies::is_concrete_klass(ctxk)) {
1184 guarantee(NULL ==
1185 (void *)check_abstract_with_no_concrete_subtype(ctxk),
1186 "verify dep.");
1187 } else {
1188 guarantee(NULL ==
1189 (void *)check_concrete_with_no_concrete_subtype(ctxk),
1190 "verify dep.");
1191 }
1192 }
1193 #endif //PRODUCT
1194 return ctxk; // Return ctxk as a flag for "no subtypes".
1195 } else {
1196 #ifndef PRODUCT
1197 // Make sure the dependency mechanism will pass this discovery:
1198 if (VerifyDependencies) {
1199 // Turn off dependency tracing while actually testing deps.
1200 FlagSetting fs(TraceDependencies, false);
1201 if (!Dependencies::is_concrete_klass(ctxk)) {
1202 guarantee(NULL == (void *)
1203 check_abstract_with_unique_concrete_subtype(ctxk, conck),
1204 "verify dep.");
1205 }
1206 }
1207 #endif //PRODUCT
1208 return conck;
1209 }
1210 }
1211
1212 // Test the assertion that the k[12] are the only concrete subtypes of ctxk,
1213 // except possibly for further subtypes of k[12] themselves.
1214 // The context type must be abstract. The types k1 and k2 are themselves
1215 // allowed to have further concrete subtypes.
1216 klassOop Dependencies::check_abstract_with_exclusive_concrete_subtypes(
1217 klassOop ctxk,
1218 klassOop k1,
1219 klassOop k2,
1220 DepChange* changes) {
1221 ClassHierarchyWalker wf;
1222 wf.add_participant(k1);
1223 wf.add_participant(k2);
1224 return wf.find_witness_subtype(ctxk, changes);
1225 }
1226
1227 // Search ctxk for concrete implementations. If there are klen or fewer,
1228 // pack them into the given array and return the number.
1229 // Otherwise, return -1, meaning the given array would overflow.
1230 // (Note that a return of 0 means there are exactly no concrete subtypes.)
1231 // In this search, if ctxk is concrete, it will be reported alone.
1232 // For any type CC reported, no proper subtypes of CC will be reported.
1233 int Dependencies::find_exclusive_concrete_subtypes(klassOop ctxk,
1234 int klen,
1235 klassOop karray[]) {
1236 ClassHierarchyWalker wf;
1237 wf.record_witnesses(klen);
1238 klassOop wit = wf.find_witness_subtype(ctxk);
1239 if (wit != NULL) return -1; // Too many witnesses.
1240 int num = wf.num_participants();
1241 assert(num <= klen, "oob");
1242 // Pack the result array with the good news.
1243 for (int i = 0; i < num; i++)
1244 karray[i] = wf.participant(i);
1245 #ifndef PRODUCT
1246 // Make sure the dependency mechanism will pass this discovery:
1247 if (VerifyDependencies) {
1248 // Turn off dependency tracing while actually testing deps.
1249 FlagSetting fs(TraceDependencies, false);
1250 switch (Dependencies::is_concrete_klass(ctxk)? -1: num) {
1251 case -1: // ctxk was itself concrete
1252 guarantee(num == 1 && karray[0] == ctxk, "verify dep.");
1253 break;
1254 case 0:
1255 guarantee(NULL == (void *)check_abstract_with_no_concrete_subtype(ctxk),
1256 "verify dep.");
1257 break;
1258 case 1:
1259 guarantee(NULL == (void *)
1260 check_abstract_with_unique_concrete_subtype(ctxk, karray[0]),
1261 "verify dep.");
1262 break;
1263 case 2:
1264 guarantee(NULL == (void *)
1265 check_abstract_with_exclusive_concrete_subtypes(ctxk,
1266 karray[0],
1267 karray[1]),
1268 "verify dep.");
1269 break;
1270 default:
1271 ShouldNotReachHere(); // klen > 2 yet supported
1272 }
1273 }
1274 #endif //PRODUCT
1275 return num;
1276 }
1277
1278 // If a class (or interface) has a unique concrete method uniqm, return NULL.
1279 // Otherwise, return a class that contains an interfering method.
1280 klassOop Dependencies::check_unique_concrete_method(klassOop ctxk, methodOop uniqm,
1281 DepChange* changes) {
1282 // Here is a missing optimization: If uniqm->is_final(),
1283 // we don't really need to search beneath it for overrides.
1284 // This is probably not important, since we don't use dependencies
1285 // to track final methods. (They can't be "definalized".)
1286 ClassHierarchyWalker wf(uniqm->method_holder(), uniqm);
1287 return wf.find_witness_definer(ctxk, changes);
1288 }
1289
1290 // Find the set of all non-abstract methods under ctxk that match m.
1291 // (The method m must be defined or inherited in ctxk.)
1292 // Include m itself in the set, unless it is abstract.
1293 // If this set has exactly one element, return that element.
1294 methodOop Dependencies::find_unique_concrete_method(klassOop ctxk, methodOop m) {
1295 ClassHierarchyWalker wf(m);
1296 assert(wf.check_method_context(ctxk, m), "proper context");
1297 wf.record_witnesses(1);
1298 klassOop wit = wf.find_witness_definer(ctxk);
1299 if (wit != NULL) return NULL; // Too many witnesses.
1300 methodOop fm = wf.found_method(0); // Will be NULL if num_parts == 0.
1301 if (Dependencies::is_concrete_method(m)) {
1302 if (fm == NULL) {
1303 // It turns out that m was always the only implementation.
1304 fm = m;
1305 } else if (fm != m) {
1306 // Two conflicting implementations after all.
1307 // (This can happen if m is inherited into ctxk and fm overrides it.)
1308 return NULL;
1309 }
1310 }
1311 #ifndef PRODUCT
1312 // Make sure the dependency mechanism will pass this discovery:
1313 if (VerifyDependencies && fm != NULL) {
1314 guarantee(NULL == (void *)check_unique_concrete_method(ctxk, fm),
1315 "verify dep.");
1316 }
1317 #endif //PRODUCT
1318 return fm;
1319 }
1320
1321 klassOop Dependencies::check_exclusive_concrete_methods(klassOop ctxk,
1322 methodOop m1,
1323 methodOop m2,
1324 DepChange* changes) {
1325 ClassHierarchyWalker wf(m1);
1326 wf.add_participant(m1->method_holder());
1327 wf.add_participant(m2->method_holder());
1328 return wf.find_witness_definer(ctxk, changes);
1329 }
1330
1331 // Find the set of all non-abstract methods under ctxk that match m[0].
1332 // (The method m[0] must be defined or inherited in ctxk.)
1333 // Include m itself in the set, unless it is abstract.
1334 // Fill the given array m[0..(mlen-1)] with this set, and return the length.
1335 // (The length may be zero if no concrete methods are found anywhere.)
1336 // If there are too many concrete methods to fit in marray, return -1.
1337 int Dependencies::find_exclusive_concrete_methods(klassOop ctxk,
1338 int mlen,
1339 methodOop marray[]) {
1340 methodOop m0 = marray[0];
1341 ClassHierarchyWalker wf(m0);
1342 assert(wf.check_method_context(ctxk, m0), "proper context");
1343 wf.record_witnesses(mlen);
1344 bool participants_hide_witnesses = true;
1345 klassOop wit = wf.find_witness_definer(ctxk);
1346 if (wit != NULL) return -1; // Too many witnesses.
1347 int num = wf.num_participants();
1348 assert(num <= mlen, "oob");
1349 // Keep track of whether m is also part of the result set.
1350 int mfill = 0;
1351 assert(marray[mfill] == m0, "sanity");
1352 if (Dependencies::is_concrete_method(m0))
1353 mfill++; // keep m0 as marray[0], the first result
1354 for (int i = 0; i < num; i++) {
1355 methodOop fm = wf.found_method(i);
1356 if (fm == m0) continue; // Already put this guy in the list.
1357 if (mfill == mlen) {
1358 return -1; // Oops. Too many methods after all!
1359 }
1360 marray[mfill++] = fm;
1361 }
1362 #ifndef PRODUCT
1363 // Make sure the dependency mechanism will pass this discovery:
1364 if (VerifyDependencies) {
1365 // Turn off dependency tracing while actually testing deps.
1366 FlagSetting fs(TraceDependencies, false);
1367 switch (mfill) {
1368 case 1:
1369 guarantee(NULL == (void *)check_unique_concrete_method(ctxk, marray[0]),
1370 "verify dep.");
1371 break;
1372 case 2:
1373 guarantee(NULL == (void *)
1374 check_exclusive_concrete_methods(ctxk, marray[0], marray[1]),
1375 "verify dep.");
1376 break;
1377 default:
1378 ShouldNotReachHere(); // mlen > 2 yet supported
1379 }
1380 }
1381 #endif //PRODUCT
1382 return mfill;
1383 }
1384
1385
1386 klassOop Dependencies::check_has_no_finalizable_subclasses(klassOop ctxk, DepChange* changes) {
1387 Klass* search_at = ctxk->klass_part();
1388 if (changes != NULL)
1389 search_at = changes->new_type()->klass_part(); // just look at the new bit
1390 Klass* result = find_finalizable_subclass(search_at);
1391 if (result == NULL) {
1392 return NULL;
1393 }
1394 return result->as_klassOop();
1395 }
1396
1397
1398 klassOop Dependencies::DepStream::check_dependency_impl(DepChange* changes) {
1399 assert_locked_or_safepoint(Compile_lock);
1400
1401 klassOop witness = NULL;
1402 switch (type()) {
1403 case evol_method:
1404 witness = check_evol_method(method_argument(0));
1405 break;
1406 case leaf_type:
1407 witness = check_leaf_type(context_type());
1408 break;
1409 case abstract_with_unique_concrete_subtype:
1410 witness = check_abstract_with_unique_concrete_subtype(context_type(),
1411 type_argument(1),
1412 changes);
1413 break;
1414 case abstract_with_no_concrete_subtype:
1415 witness = check_abstract_with_no_concrete_subtype(context_type(),
1416 changes);
1417 break;
1418 case concrete_with_no_concrete_subtype:
1419 witness = check_concrete_with_no_concrete_subtype(context_type(),
1420 changes);
1421 break;
1422 case unique_concrete_method:
1423 witness = check_unique_concrete_method(context_type(),
1424 method_argument(1),
1425 changes);
1426 break;
1427 case abstract_with_exclusive_concrete_subtypes_2:
1428 witness = check_abstract_with_exclusive_concrete_subtypes(context_type(),
1429 type_argument(1),
1430 type_argument(2),
1431 changes);
1432 break;
1433 case exclusive_concrete_methods_2:
1434 witness = check_exclusive_concrete_methods(context_type(),
1435 method_argument(1),
1436 method_argument(2),
1437 changes);
1438 break;
1439 case no_finalizable_subclasses:
1440 witness = check_has_no_finalizable_subclasses(context_type(),
1441 changes);
1442 break;
1443 default:
1444 witness = NULL;
1445 ShouldNotReachHere();
1446 break;
1447 }
1448 if (witness != NULL) {
1449 if (TraceDependencies) {
1450 print_dependency(witness, /*verbose=*/ true);
1451 }
1452 // The following is a no-op unless logging is enabled:
1453 log_dependency(witness);
1454 }
1455 return witness;
1456 }
1457
1458
1459 klassOop Dependencies::DepStream::spot_check_dependency_at(DepChange& changes) {
1460 if (!changes.involves_context(context_type()))
1461 // irrelevant dependency; skip it
1462 return NULL;
1463
1464 return check_dependency_impl(&changes);
1465 }
1466
1467
1468 void DepChange::initialize() {
1469 // entire transaction must be under this lock:
1470 assert_lock_strong(Compile_lock);
1471
1472 // Mark all dependee and all its superclasses
1473 // Mark transitive interfaces
1474 for (ContextStream str(*this); str.next(); ) {
1475 klassOop d = str.klass();
1476 assert(!instanceKlass::cast(d)->is_marked_dependent(), "checking");
1477 instanceKlass::cast(d)->set_is_marked_dependent(true);
1478 }
1479 }
1480
1481 DepChange::~DepChange() {
1482 // Unmark all dependee and all its superclasses
1483 // Unmark transitive interfaces
1484 for (ContextStream str(*this); str.next(); ) {
1485 klassOop d = str.klass();
1486 instanceKlass::cast(d)->set_is_marked_dependent(false);
1487 }
1488 }
1489
1490 bool DepChange::involves_context(klassOop k) {
1491 if (k == NULL || !Klass::cast(k)->oop_is_instance()) {
1492 return false;
1493 }
1494 instanceKlass* ik = instanceKlass::cast(k);
1495 bool is_contained = ik->is_marked_dependent();
1496 assert(is_contained == Klass::cast(new_type())->is_subtype_of(k),
1497 "correct marking of potential context types");
1498 return is_contained;
1499 }
1500
1501 bool DepChange::ContextStream::next() {
1502 switch (_change_type) {
1503 case Start_Klass: // initial state; _klass is the new type
1504 _ti_base = instanceKlass::cast(_klass)->transitive_interfaces();
1505 _ti_index = 0;
1506 _change_type = Change_new_type;
1507 return true;
1508 case Change_new_type:
1509 // fall through:
1510 _change_type = Change_new_sub;
1511 case Change_new_sub:
1512 // 6598190: brackets workaround Sun Studio C++ compiler bug 6629277
1513 {
1514 _klass = instanceKlass::cast(_klass)->super();
1515 if (_klass != NULL) {
1516 return true;
1517 }
1518 }
1519 // else set up _ti_limit and fall through:
1520 _ti_limit = (_ti_base == NULL) ? 0 : _ti_base->length();
1521 _change_type = Change_new_impl;
1522 case Change_new_impl:
1523 if (_ti_index < _ti_limit) {
1524 _klass = klassOop( _ti_base->obj_at(_ti_index++) );
1525 return true;
1526 }
1527 // fall through:
1528 _change_type = NO_CHANGE; // iterator is exhausted
1529 case NO_CHANGE:
1530 break;
1531 default:
1532 ShouldNotReachHere();
1533 }
1534 return false;
1535 }
1536
1537 void DepChange::print() {
1538 int nsup = 0, nint = 0;
1539 for (ContextStream str(*this); str.next(); ) {
1540 klassOop k = str.klass();
1541 switch (str.change_type()) {
1542 case Change_new_type:
1543 tty->print_cr(" dependee = %s", instanceKlass::cast(k)->external_name());
1544 break;
1545 case Change_new_sub:
1546 if (!WizardMode) {
1547 ++nsup;
1548 } else {
1549 tty->print_cr(" context super = %s", instanceKlass::cast(k)->external_name());
1550 }
1551 break;
1552 case Change_new_impl:
1553 if (!WizardMode) {
1554 ++nint;
1555 } else {
1556 tty->print_cr(" context interface = %s", instanceKlass::cast(k)->external_name());
1557 }
1558 break;
1559 }
1560 }
1561 if (nsup + nint != 0) {
1562 tty->print_cr(" context supers = %d, interfaces = %d", nsup, nint);
1563 }
1564 }
1565
1566 #ifndef PRODUCT
1567 void Dependencies::print_statistics() {
1568 if (deps_find_witness_print != 0) {
1569 // Call one final time, to flush out the data.
1570 deps_find_witness_print = -1;
1571 count_find_witness_calls();
1572 }
1573 }
1574 #endif