1 /*
2 * Copyright (c) 2005, 2025, 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 "ci/ciArrayKlass.hpp"
26 #include "ci/ciEnv.hpp"
27 #include "ci/ciKlass.hpp"
28 #include "ci/ciMethod.hpp"
29 #include "classfile/javaClasses.inline.hpp"
30 #include "classfile/vmClasses.hpp"
31 #include "code/dependencies.hpp"
32 #include "compiler/compileLog.hpp"
33 #include "compiler/compileBroker.hpp"
34 #include "compiler/compileTask.hpp"
35 #include "memory/resourceArea.hpp"
36 #include "oops/klass.hpp"
37 #include "oops/oop.inline.hpp"
38 #include "oops/method.inline.hpp"
39 #include "oops/objArrayKlass.hpp"
40 #include "runtime/flags/flagSetting.hpp"
41 #include "runtime/handles.hpp"
42 #include "runtime/handles.inline.hpp"
43 #include "runtime/javaThread.inline.hpp"
44 #include "runtime/jniHandles.inline.hpp"
45 #include "runtime/mutexLocker.hpp"
46 #include "runtime/perfData.hpp"
47 #include "runtime/vmThread.hpp"
48 #include "utilities/copy.hpp"
49
50
51 #ifdef ASSERT
52 static bool must_be_in_vm() {
53 Thread* thread = Thread::current();
54 if (thread->is_Java_thread()) {
55 return JavaThread::cast(thread)->thread_state() == _thread_in_vm;
56 } else {
57 return true; // Could be VMThread or GC thread
58 }
59 }
60 #endif //ASSERT
61
62 bool Dependencies::_verify_in_progress = false; // don't -Xlog:dependencies
63
64 void Dependencies::initialize(ciEnv* env) {
65 Arena* arena = env->arena();
66 _oop_recorder = env->oop_recorder();
67 _log = env->log();
68 _dep_seen = new(arena) GrowableArray<int>(arena, 500, 0, 0);
69 #if INCLUDE_JVMCI
70 _using_dep_values = false;
71 #endif
72 DEBUG_ONLY(_deps[end_marker] = nullptr);
73 for (int i = (int)FIRST_TYPE; i < (int)TYPE_LIMIT; i++) {
74 _deps[i] = new(arena) GrowableArray<ciBaseObject*>(arena, 10, 0, nullptr);
75 }
76 _content_bytes = nullptr;
77 _size_in_bytes = (size_t)-1;
78
79 assert(TYPE_LIMIT <= (1<<LG2_TYPE_LIMIT), "sanity");
80 }
81
82 void Dependencies::assert_evol_method(ciMethod* m) {
83 assert_common_1(evol_method, m);
84 }
85
86 void Dependencies::assert_leaf_type(ciKlass* ctxk) {
87 if (ctxk->is_array_klass()) {
88 // As a special case, support this assertion on an array type,
89 // which reduces to an assertion on its element type.
90 // Note that this cannot be done with assertions that
91 // relate to concreteness or abstractness.
92 ciType* elemt = ctxk->as_array_klass()->base_element_type();
93 if (!elemt->is_instance_klass()) return; // Ex: int[][]
94 ctxk = elemt->as_instance_klass();
95 //if (ctxk->is_final()) return; // Ex: String[][]
96 }
97 check_ctxk(ctxk);
98 assert_common_1(leaf_type, ctxk);
99 }
100
101 void Dependencies::assert_abstract_with_unique_concrete_subtype(ciKlass* ctxk, ciKlass* conck) {
102 check_ctxk_abstract(ctxk);
103 assert_common_2(abstract_with_unique_concrete_subtype, ctxk, conck);
104 }
105
106 void Dependencies::assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm) {
107 check_ctxk(ctxk);
108 check_unique_method(ctxk, uniqm);
109 assert_common_2(unique_concrete_method_2, ctxk, uniqm);
110 }
111
112 void Dependencies::assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm, ciKlass* resolved_klass, ciMethod* resolved_method) {
113 check_ctxk(ctxk);
114 check_unique_method(ctxk, uniqm);
115 assert_common_4(unique_concrete_method_4, ctxk, uniqm, resolved_klass, resolved_method);
116 }
117
118 void Dependencies::assert_unique_implementor(ciInstanceKlass* ctxk, ciInstanceKlass* uniqk) {
119 check_ctxk(ctxk);
120 check_unique_implementor(ctxk, uniqk);
121 assert_common_2(unique_implementor, ctxk, uniqk);
122 }
123
124 void Dependencies::assert_has_no_finalizable_subclasses(ciKlass* ctxk) {
125 check_ctxk(ctxk);
126 assert_common_1(no_finalizable_subclasses, ctxk);
127 }
128
129 void Dependencies::assert_call_site_target_value(ciCallSite* call_site, ciMethodHandle* method_handle) {
130 assert_common_2(call_site_target_value, call_site, method_handle);
131 }
132
133 #if INCLUDE_JVMCI
134
135 Dependencies::Dependencies(Arena* arena, OopRecorder* oop_recorder, CompileLog* log) {
136 _oop_recorder = oop_recorder;
137 _log = log;
138 _dep_seen = new(arena) GrowableArray<int>(arena, 500, 0, 0);
139 _using_dep_values = true;
140 DEBUG_ONLY(_dep_values[end_marker] = nullptr);
141 for (int i = (int)FIRST_TYPE; i < (int)TYPE_LIMIT; i++) {
142 _dep_values[i] = new(arena) GrowableArray<DepValue>(arena, 10, 0, DepValue());
143 }
144 _content_bytes = nullptr;
145 _size_in_bytes = (size_t)-1;
146
147 assert(TYPE_LIMIT <= (1<<LG2_TYPE_LIMIT), "sanity");
148 }
149
150 void Dependencies::assert_evol_method(Method* m) {
151 assert_common_1(evol_method, DepValue(_oop_recorder, m));
152 }
153
154 void Dependencies::assert_has_no_finalizable_subclasses(Klass* ctxk) {
155 check_ctxk(ctxk);
156 assert_common_1(no_finalizable_subclasses, DepValue(_oop_recorder, ctxk));
157 }
158
159 void Dependencies::assert_leaf_type(Klass* ctxk) {
160 if (ctxk->is_array_klass()) {
161 // As a special case, support this assertion on an array type,
162 // which reduces to an assertion on its element type.
163 // Note that this cannot be done with assertions that
164 // relate to concreteness or abstractness.
165 BasicType elemt = ArrayKlass::cast(ctxk)->element_type();
166 if (is_java_primitive(elemt)) return; // Ex: int[][]
167 ctxk = ObjArrayKlass::cast(ctxk)->bottom_klass();
168 //if (ctxk->is_final()) return; // Ex: String[][]
169 }
170 check_ctxk(ctxk);
171 assert_common_1(leaf_type, DepValue(_oop_recorder, ctxk));
172 }
173
174 void Dependencies::assert_abstract_with_unique_concrete_subtype(Klass* ctxk, Klass* conck) {
175 check_ctxk_abstract(ctxk);
176 DepValue ctxk_dv(_oop_recorder, ctxk);
177 DepValue conck_dv(_oop_recorder, conck, &ctxk_dv);
178 assert_common_2(abstract_with_unique_concrete_subtype, ctxk_dv, conck_dv);
179 }
180
181 void Dependencies::assert_unique_implementor(InstanceKlass* ctxk, InstanceKlass* uniqk) {
182 check_ctxk(ctxk);
183 assert(ctxk->is_interface(), "not an interface");
184 assert(ctxk->implementor() == uniqk, "not a unique implementor");
185 assert_common_2(unique_implementor, DepValue(_oop_recorder, ctxk), DepValue(_oop_recorder, uniqk));
186 }
187
188 void Dependencies::assert_unique_concrete_method(Klass* ctxk, Method* uniqm) {
189 check_ctxk(ctxk);
190 check_unique_method(ctxk, uniqm);
191 assert_common_2(unique_concrete_method_2, DepValue(_oop_recorder, ctxk), DepValue(_oop_recorder, uniqm));
192 }
193
194 void Dependencies::assert_call_site_target_value(oop call_site, oop method_handle) {
195 assert_common_2(call_site_target_value, DepValue(_oop_recorder, JNIHandles::make_local(call_site)), DepValue(_oop_recorder, JNIHandles::make_local(method_handle)));
196 }
197
198 #endif // INCLUDE_JVMCI
199
200
201 // Helper function. If we are adding a new dep. under ctxk2,
202 // try to find an old dep. under a broader* ctxk1. If there is
203 //
204 bool Dependencies::maybe_merge_ctxk(GrowableArray<ciBaseObject*>* deps,
205 int ctxk_i, ciKlass* ctxk2) {
206 ciKlass* ctxk1 = deps->at(ctxk_i)->as_metadata()->as_klass();
207 if (ctxk2->is_subtype_of(ctxk1)) {
208 return true; // success, and no need to change
209 } else if (ctxk1->is_subtype_of(ctxk2)) {
210 // new context class fully subsumes previous one
211 deps->at_put(ctxk_i, ctxk2);
212 return true;
213 } else {
214 return false;
215 }
216 }
217
218 void Dependencies::assert_common_1(DepType dept, ciBaseObject* x) {
219 assert(dep_args(dept) == 1, "sanity");
220 log_dependency(dept, x);
221 GrowableArray<ciBaseObject*>* deps = _deps[dept];
222
223 // see if the same (or a similar) dep is already recorded
224 if (note_dep_seen(dept, x)) {
225 assert(deps->find(x) >= 0, "sanity");
226 } else {
227 deps->append(x);
228 }
229 }
230
231 void Dependencies::assert_common_2(DepType dept,
232 ciBaseObject* x0, ciBaseObject* x1) {
233 assert(dep_args(dept) == 2, "sanity");
234 log_dependency(dept, x0, x1);
235 GrowableArray<ciBaseObject*>* deps = _deps[dept];
236
237 // see if the same (or a similar) dep is already recorded
238 bool has_ctxk = has_explicit_context_arg(dept);
239 if (has_ctxk) {
240 assert(dep_context_arg(dept) == 0, "sanity");
241 if (note_dep_seen(dept, x1)) {
242 // look in this bucket for redundant assertions
243 const int stride = 2;
244 for (int i = deps->length(); (i -= stride) >= 0; ) {
245 ciBaseObject* y1 = deps->at(i+1);
246 if (x1 == y1) { // same subject; check the context
247 if (maybe_merge_ctxk(deps, i+0, x0->as_metadata()->as_klass())) {
248 return;
249 }
250 }
251 }
252 }
253 } else {
254 bool dep_seen_x0 = note_dep_seen(dept, x0); // records x0 for future queries
255 bool dep_seen_x1 = note_dep_seen(dept, x1); // records x1 for future queries
256 if (dep_seen_x0 && dep_seen_x1) {
257 // look in this bucket for redundant assertions
258 const int stride = 2;
259 for (int i = deps->length(); (i -= stride) >= 0; ) {
260 ciBaseObject* y0 = deps->at(i+0);
261 ciBaseObject* y1 = deps->at(i+1);
262 if (x0 == y0 && x1 == y1) {
263 return;
264 }
265 }
266 }
267 }
268
269 // append the assertion in the correct bucket:
270 deps->append(x0);
271 deps->append(x1);
272 }
273
274 void Dependencies::assert_common_4(DepType dept,
275 ciKlass* ctxk, ciBaseObject* x1, ciBaseObject* x2, ciBaseObject* x3) {
276 assert(has_explicit_context_arg(dept), "sanity");
277 assert(dep_context_arg(dept) == 0, "sanity");
278 assert(dep_args(dept) == 4, "sanity");
279 log_dependency(dept, ctxk, x1, x2, x3);
280 GrowableArray<ciBaseObject*>* deps = _deps[dept];
281
282 // see if the same (or a similar) dep is already recorded
283 bool dep_seen_x1 = note_dep_seen(dept, x1); // records x1 for future queries
284 bool dep_seen_x2 = note_dep_seen(dept, x2); // records x2 for future queries
285 bool dep_seen_x3 = note_dep_seen(dept, x3); // records x3 for future queries
286 if (dep_seen_x1 && dep_seen_x2 && dep_seen_x3) {
287 // look in this bucket for redundant assertions
288 const int stride = 4;
289 for (int i = deps->length(); (i -= stride) >= 0; ) {
290 ciBaseObject* y1 = deps->at(i+1);
291 ciBaseObject* y2 = deps->at(i+2);
292 ciBaseObject* y3 = deps->at(i+3);
293 if (x1 == y1 && x2 == y2 && x3 == y3) { // same subjects; check the context
294 if (maybe_merge_ctxk(deps, i+0, ctxk)) {
295 return;
296 }
297 }
298 }
299 }
300 // append the assertion in the correct bucket:
301 deps->append(ctxk);
302 deps->append(x1);
303 deps->append(x2);
304 deps->append(x3);
305 }
306
307 #if INCLUDE_JVMCI
308 bool Dependencies::maybe_merge_ctxk(GrowableArray<DepValue>* deps,
309 int ctxk_i, DepValue ctxk2_dv) {
310 Klass* ctxk1 = deps->at(ctxk_i).as_klass(_oop_recorder);
311 Klass* ctxk2 = ctxk2_dv.as_klass(_oop_recorder);
312 if (ctxk2->is_subtype_of(ctxk1)) {
313 return true; // success, and no need to change
314 } else if (ctxk1->is_subtype_of(ctxk2)) {
315 // new context class fully subsumes previous one
316 deps->at_put(ctxk_i, ctxk2_dv);
317 return true;
318 } else {
319 return false;
320 }
321 }
322
323 void Dependencies::assert_common_1(DepType dept, DepValue x) {
324 assert(dep_args(dept) == 1, "sanity");
325 //log_dependency(dept, x);
326 GrowableArray<DepValue>* deps = _dep_values[dept];
327
328 // see if the same (or a similar) dep is already recorded
329 if (note_dep_seen(dept, x)) {
330 assert(deps->find(x) >= 0, "sanity");
331 } else {
332 deps->append(x);
333 }
334 }
335
336 void Dependencies::assert_common_2(DepType dept,
337 DepValue x0, DepValue x1) {
338 assert(dep_args(dept) == 2, "sanity");
339 //log_dependency(dept, x0, x1);
340 GrowableArray<DepValue>* deps = _dep_values[dept];
341
342 // see if the same (or a similar) dep is already recorded
343 bool has_ctxk = has_explicit_context_arg(dept);
344 if (has_ctxk) {
345 assert(dep_context_arg(dept) == 0, "sanity");
346 if (note_dep_seen(dept, x1)) {
347 // look in this bucket for redundant assertions
348 const int stride = 2;
349 for (int i = deps->length(); (i -= stride) >= 0; ) {
350 DepValue y1 = deps->at(i+1);
351 if (x1 == y1) { // same subject; check the context
352 if (maybe_merge_ctxk(deps, i+0, x0)) {
353 return;
354 }
355 }
356 }
357 }
358 } else {
359 bool dep_seen_x0 = note_dep_seen(dept, x0); // records x0 for future queries
360 bool dep_seen_x1 = note_dep_seen(dept, x1); // records x1 for future queries
361 if (dep_seen_x0 && dep_seen_x1) {
362 // look in this bucket for redundant assertions
363 const int stride = 2;
364 for (int i = deps->length(); (i -= stride) >= 0; ) {
365 DepValue y0 = deps->at(i+0);
366 DepValue y1 = deps->at(i+1);
367 if (x0 == y0 && x1 == y1) {
368 return;
369 }
370 }
371 }
372 }
373
374 // append the assertion in the correct bucket:
375 deps->append(x0);
376 deps->append(x1);
377 }
378 #endif // INCLUDE_JVMCI
379
380 /// Support for encoding dependencies into an nmethod:
381
382 void Dependencies::copy_to(nmethod* nm) {
383 address beg = nm->dependencies_begin();
384 address end = nm->dependencies_end();
385 guarantee(end - beg >= (ptrdiff_t) size_in_bytes(), "bad sizing");
386 (void)memcpy(beg, content_bytes(), size_in_bytes());
387 assert(size_in_bytes() % sizeof(HeapWord) == 0, "copy by words");
388 }
389
390 static int sort_dep(ciBaseObject** p1, ciBaseObject** p2, int narg) {
391 for (int i = 0; i < narg; i++) {
392 int diff = p1[i]->ident() - p2[i]->ident();
393 if (diff != 0) return diff;
394 }
395 return 0;
396 }
397 static int sort_dep_arg_1(ciBaseObject** p1, ciBaseObject** p2)
398 { return sort_dep(p1, p2, 1); }
399 static int sort_dep_arg_2(ciBaseObject** p1, ciBaseObject** p2)
400 { return sort_dep(p1, p2, 2); }
401 static int sort_dep_arg_3(ciBaseObject** p1, ciBaseObject** p2)
402 { return sort_dep(p1, p2, 3); }
403 static int sort_dep_arg_4(ciBaseObject** p1, ciBaseObject** p2)
404 { return sort_dep(p1, p2, 4); }
405
406 #if INCLUDE_JVMCI
407 // metadata deps are sorted before object deps
408 static int sort_dep_value(Dependencies::DepValue* p1, Dependencies::DepValue* p2, int narg) {
409 for (int i = 0; i < narg; i++) {
410 int diff = p1[i].sort_key() - p2[i].sort_key();
411 if (diff != 0) return diff;
412 }
413 return 0;
414 }
415 static int sort_dep_value_arg_1(Dependencies::DepValue* p1, Dependencies::DepValue* p2)
416 { return sort_dep_value(p1, p2, 1); }
417 static int sort_dep_value_arg_2(Dependencies::DepValue* p1, Dependencies::DepValue* p2)
418 { return sort_dep_value(p1, p2, 2); }
419 static int sort_dep_value_arg_3(Dependencies::DepValue* p1, Dependencies::DepValue* p2)
420 { return sort_dep_value(p1, p2, 3); }
421 #endif // INCLUDE_JVMCI
422
423 void Dependencies::sort_all_deps() {
424 #if INCLUDE_JVMCI
425 if (_using_dep_values) {
426 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
427 DepType dept = (DepType)deptv;
428 GrowableArray<DepValue>* deps = _dep_values[dept];
429 if (deps->length() <= 1) continue;
430 switch (dep_args(dept)) {
431 case 1: deps->sort(sort_dep_value_arg_1, 1); break;
432 case 2: deps->sort(sort_dep_value_arg_2, 2); break;
433 case 3: deps->sort(sort_dep_value_arg_3, 3); break;
434 default: ShouldNotReachHere(); break;
435 }
436 }
437 return;
438 }
439 #endif // INCLUDE_JVMCI
440 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
441 DepType dept = (DepType)deptv;
442 GrowableArray<ciBaseObject*>* deps = _deps[dept];
443 if (deps->length() <= 1) continue;
444 switch (dep_args(dept)) {
445 case 1: deps->sort(sort_dep_arg_1, 1); break;
446 case 2: deps->sort(sort_dep_arg_2, 2); break;
447 case 3: deps->sort(sort_dep_arg_3, 3); break;
448 case 4: deps->sort(sort_dep_arg_4, 4); break;
449 default: ShouldNotReachHere(); break;
450 }
451 }
452 }
453
454 size_t Dependencies::estimate_size_in_bytes() {
455 size_t est_size = 100;
456 #if INCLUDE_JVMCI
457 if (_using_dep_values) {
458 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
459 DepType dept = (DepType)deptv;
460 GrowableArray<DepValue>* deps = _dep_values[dept];
461 est_size += deps->length() * 2; // tags and argument(s)
462 }
463 return est_size;
464 }
465 #endif // INCLUDE_JVMCI
466 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
467 DepType dept = (DepType)deptv;
468 GrowableArray<ciBaseObject*>* deps = _deps[dept];
469 est_size += deps->length()*2; // tags and argument(s)
470 }
471 return est_size;
472 }
473
474 ciKlass* Dependencies::ctxk_encoded_as_null(DepType dept, ciBaseObject* x) {
475 switch (dept) {
476 case unique_concrete_method_2:
477 case unique_concrete_method_4:
478 return x->as_metadata()->as_method()->holder();
479 default:
480 return nullptr; // let nullptr be nullptr
481 }
482 }
483
484 Klass* Dependencies::ctxk_encoded_as_null(DepType dept, Metadata* x) {
485 assert(must_be_in_vm(), "raw oops here");
486 switch (dept) {
487 case unique_concrete_method_2:
488 case unique_concrete_method_4:
489 assert(x->is_method(), "sanity");
490 return ((Method*)x)->method_holder();
491 default:
492 return nullptr; // let nullptr be nullptr
493 }
494 }
495
496 void Dependencies::encode_content_bytes() {
497 sort_all_deps();
498
499 // cast is safe, no deps can overflow INT_MAX
500 CompressedWriteStream bytes((int)estimate_size_in_bytes());
501
502 #if INCLUDE_JVMCI
503 if (_using_dep_values) {
504 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
505 DepType dept = (DepType)deptv;
506 GrowableArray<DepValue>* deps = _dep_values[dept];
507 if (deps->length() == 0) continue;
508 int stride = dep_args(dept);
509 int ctxkj = dep_context_arg(dept); // -1 if no context arg
510 assert(stride > 0, "sanity");
511 for (int i = 0; i < deps->length(); i += stride) {
512 jbyte code_byte = (jbyte)dept;
513 int skipj = -1;
514 if (ctxkj >= 0 && ctxkj+1 < stride) {
515 Klass* ctxk = deps->at(i+ctxkj+0).as_klass(_oop_recorder);
516 DepValue x = deps->at(i+ctxkj+1); // following argument
517 if (ctxk == ctxk_encoded_as_null(dept, x.as_metadata(_oop_recorder))) {
518 skipj = ctxkj; // we win: maybe one less oop to keep track of
519 code_byte |= default_context_type_bit;
520 }
521 }
522 bytes.write_byte(code_byte);
523 for (int j = 0; j < stride; j++) {
524 if (j == skipj) continue;
525 DepValue v = deps->at(i+j);
526 int idx = v.index();
527 bytes.write_int(idx);
528 }
529 }
530 }
531 } else {
532 #endif // INCLUDE_JVMCI
533 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
534 DepType dept = (DepType)deptv;
535 GrowableArray<ciBaseObject*>* deps = _deps[dept];
536 if (deps->length() == 0) continue;
537 int stride = dep_args(dept);
538 int ctxkj = dep_context_arg(dept); // -1 if no context arg
539 assert(stride > 0, "sanity");
540 for (int i = 0; i < deps->length(); i += stride) {
541 jbyte code_byte = (jbyte)dept;
542 int skipj = -1;
543 if (ctxkj >= 0 && ctxkj+1 < stride) {
544 ciKlass* ctxk = deps->at(i+ctxkj+0)->as_metadata()->as_klass();
545 ciBaseObject* x = deps->at(i+ctxkj+1); // following argument
546 if (ctxk == ctxk_encoded_as_null(dept, x)) {
547 skipj = ctxkj; // we win: maybe one less oop to keep track of
548 code_byte |= default_context_type_bit;
549 }
550 }
551 bytes.write_byte(code_byte);
552 for (int j = 0; j < stride; j++) {
553 if (j == skipj) continue;
554 ciBaseObject* v = deps->at(i+j);
555 int idx;
556 if (v->is_object()) {
557 idx = _oop_recorder->find_index(v->as_object()->constant_encoding());
558 } else {
559 ciMetadata* meta = v->as_metadata();
560 idx = _oop_recorder->find_index(meta->constant_encoding());
561 }
562 bytes.write_int(idx);
563 }
564 }
565 }
566 #if INCLUDE_JVMCI
567 }
568 #endif
569
570 // write a sentinel byte to mark the end
571 bytes.write_byte(end_marker);
572
573 // round it out to a word boundary
574 while (bytes.position() % sizeof(HeapWord) != 0) {
575 bytes.write_byte(end_marker);
576 }
577
578 // check whether the dept byte encoding really works
579 assert((jbyte)default_context_type_bit != 0, "byte overflow");
580
581 _content_bytes = bytes.buffer();
582 _size_in_bytes = bytes.position();
583 }
584
585
586 const char* Dependencies::_dep_name[TYPE_LIMIT] = {
587 "end_marker",
588 "evol_method",
589 "leaf_type",
590 "abstract_with_unique_concrete_subtype",
591 "unique_concrete_method_2",
592 "unique_concrete_method_4",
593 "unique_implementor",
594 "no_finalizable_subclasses",
595 "call_site_target_value"
596 };
597
598 int Dependencies::_dep_args[TYPE_LIMIT] = {
599 -1,// end_marker
600 1, // evol_method m
601 1, // leaf_type ctxk
602 2, // abstract_with_unique_concrete_subtype ctxk, k
603 2, // unique_concrete_method_2 ctxk, m
604 4, // unique_concrete_method_4 ctxk, m, resolved_klass, resolved_method
605 2, // unique_implementor ctxk, implementor
606 1, // no_finalizable_subclasses ctxk
607 2 // call_site_target_value call_site, method_handle
608 };
609
610 const char* Dependencies::dep_name(Dependencies::DepType dept) {
611 if (!dept_in_mask(dept, all_types)) return "?bad-dep?";
612 return _dep_name[dept];
613 }
614
615 int Dependencies::dep_args(Dependencies::DepType dept) {
616 if (!dept_in_mask(dept, all_types)) return -1;
617 return _dep_args[dept];
618 }
619
620 void Dependencies::check_valid_dependency_type(DepType dept) {
621 guarantee(FIRST_TYPE <= dept && dept < TYPE_LIMIT, "invalid dependency type: %d", (int) dept);
622 }
623
624 Dependencies::DepType Dependencies::validate_dependencies(CompileTask* task, char** failure_detail) {
625 int klass_violations = 0;
626 DepType result = end_marker;
627 for (Dependencies::DepStream deps(this); deps.next(); ) {
628 Klass* witness = deps.check_dependency();
629 if (witness != nullptr) {
630 if (klass_violations == 0) {
631 result = deps.type();
632 if (failure_detail != nullptr && klass_violations == 0) {
633 // Use a fixed size buffer to prevent the string stream from
634 // resizing in the context of an inner resource mark.
635 char* buffer = NEW_RESOURCE_ARRAY(char, O_BUFLEN);
636 stringStream st(buffer, O_BUFLEN);
637 deps.print_dependency(&st, witness, true);
638 *failure_detail = st.as_string();
639 }
640 }
641 klass_violations++;
642 if (xtty == nullptr) {
643 // If we're not logging then a single violation is sufficient,
644 // otherwise we want to log all the dependences which were
645 // violated.
646 break;
647 }
648 }
649 }
650
651 return result;
652 }
653
654 // for the sake of the compiler log, print out current dependencies:
655 void Dependencies::log_all_dependencies() {
656 if (log() == nullptr) return;
657 ResourceMark rm;
658 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
659 DepType dept = (DepType)deptv;
660 GrowableArray<ciBaseObject*>* deps = _deps[dept];
661 int deplen = deps->length();
662 if (deplen == 0) {
663 continue;
664 }
665 int stride = dep_args(dept);
666 GrowableArray<ciBaseObject*>* ciargs = new GrowableArray<ciBaseObject*>(stride);
667 for (int i = 0; i < deps->length(); i += stride) {
668 for (int j = 0; j < stride; j++) {
669 // flush out the identities before printing
670 ciargs->push(deps->at(i+j));
671 }
672 write_dependency_to(log(), dept, ciargs);
673 ciargs->clear();
674 }
675 guarantee(deplen == deps->length(), "deps array cannot grow inside nested ResoureMark scope");
676 }
677 }
678
679 void Dependencies::write_dependency_to(CompileLog* log,
680 DepType dept,
681 GrowableArray<DepArgument>* args,
682 Klass* witness) {
683 if (log == nullptr) {
684 return;
685 }
686 ResourceMark rm;
687 ciEnv* env = ciEnv::current();
688 GrowableArray<ciBaseObject*>* ciargs = new GrowableArray<ciBaseObject*>(args->length());
689 for (GrowableArrayIterator<DepArgument> it = args->begin(); it != args->end(); ++it) {
690 DepArgument arg = *it;
691 if (arg.is_oop()) {
692 ciargs->push(env->get_object(arg.oop_value()));
693 } else {
694 ciargs->push(env->get_metadata(arg.metadata_value()));
695 }
696 }
697 int argslen = ciargs->length();
698 Dependencies::write_dependency_to(log, dept, ciargs, witness);
699 guarantee(argslen == ciargs->length(), "ciargs array cannot grow inside nested ResoureMark scope");
700 }
701
702 void Dependencies::write_dependency_to(CompileLog* log,
703 DepType dept,
704 GrowableArray<ciBaseObject*>* args,
705 Klass* witness) {
706 if (log == nullptr) {
707 return;
708 }
709 ResourceMark rm;
710 GrowableArray<int>* argids = new GrowableArray<int>(args->length());
711 for (GrowableArrayIterator<ciBaseObject*> it = args->begin(); it != args->end(); ++it) {
712 ciBaseObject* obj = *it;
713 if (obj->is_object()) {
714 argids->push(log->identify(obj->as_object()));
715 } else {
716 argids->push(log->identify(obj->as_metadata()));
717 }
718 }
719 if (witness != nullptr) {
720 log->begin_elem("dependency_failed");
721 } else {
722 log->begin_elem("dependency");
723 }
724 log->print(" type='%s'", dep_name(dept));
725 const int ctxkj = dep_context_arg(dept); // -1 if no context arg
726 if (ctxkj >= 0 && ctxkj < argids->length()) {
727 log->print(" ctxk='%d'", argids->at(ctxkj));
728 }
729 // write remaining arguments, if any.
730 for (int j = 0; j < argids->length(); j++) {
731 if (j == ctxkj) continue; // already logged
732 if (j == 1) {
733 log->print( " x='%d'", argids->at(j));
734 } else {
735 log->print(" x%d='%d'", j, argids->at(j));
736 }
737 }
738 if (witness != nullptr) {
739 log->object("witness", witness);
740 log->stamp();
741 }
742 log->end_elem();
743 }
744
745 void Dependencies::write_dependency_to(xmlStream* xtty,
746 DepType dept,
747 GrowableArray<DepArgument>* args,
748 Klass* witness) {
749 if (xtty == nullptr) {
750 return;
751 }
752 Thread* thread = Thread::current();
753 HandleMark rm(thread);
754 ttyLocker ttyl;
755 int ctxkj = dep_context_arg(dept); // -1 if no context arg
756 if (witness != nullptr) {
757 xtty->begin_elem("dependency_failed");
758 } else {
759 xtty->begin_elem("dependency");
760 }
761 xtty->print(" type='%s'", dep_name(dept));
762 if (ctxkj >= 0) {
763 xtty->object("ctxk", args->at(ctxkj).metadata_value());
764 }
765 // write remaining arguments, if any.
766 for (int j = 0; j < args->length(); j++) {
767 if (j == ctxkj) continue; // already logged
768 DepArgument arg = args->at(j);
769 if (j == 1) {
770 if (arg.is_oop()) {
771 xtty->object("x", Handle(thread, arg.oop_value()));
772 } else {
773 xtty->object("x", arg.metadata_value());
774 }
775 } else {
776 char xn[12];
777 os::snprintf_checked(xn, sizeof(xn), "x%d", j);
778 if (arg.is_oop()) {
779 xtty->object(xn, Handle(thread, arg.oop_value()));
780 } else {
781 xtty->object(xn, arg.metadata_value());
782 }
783 }
784 }
785 if (witness != nullptr) {
786 xtty->object("witness", witness);
787 xtty->stamp();
788 }
789 xtty->end_elem();
790 }
791
792 void Dependencies::print_dependency(DepType dept, GrowableArray<DepArgument>* args,
793 Klass* witness, outputStream* st) {
794 ResourceMark rm;
795 ttyLocker ttyl; // keep the following output all in one block
796 st->print_cr("%s of type %s",
797 (witness == nullptr)? "Dependency": "Failed dependency",
798 dep_name(dept));
799 // print arguments
800 int ctxkj = dep_context_arg(dept); // -1 if no context arg
801 for (int j = 0; j < args->length(); j++) {
802 DepArgument arg = args->at(j);
803 bool put_star = false;
804 if (arg.is_null()) continue;
805 const char* what;
806 if (j == ctxkj) {
807 assert(arg.is_metadata(), "must be");
808 what = "context";
809 put_star = !Dependencies::is_concrete_klass((Klass*)arg.metadata_value());
810 } else if (arg.is_method()) {
811 what = "method ";
812 put_star = !Dependencies::is_concrete_method((Method*)arg.metadata_value(), nullptr);
813 } else if (arg.is_klass()) {
814 what = "class ";
815 } else {
816 what = "object ";
817 }
818 st->print(" %s = %s", what, (put_star? "*": ""));
819 if (arg.is_klass()) {
820 st->print("%s", ((Klass*)arg.metadata_value())->external_name());
821 } else if (arg.is_method()) {
822 ((Method*)arg.metadata_value())->print_value_on(st);
823 } else if (arg.is_oop()) {
824 arg.oop_value()->print_value_on(st);
825 } else {
826 ShouldNotReachHere(); // Provide impl for this type.
827 }
828
829 st->cr();
830 }
831 if (witness != nullptr) {
832 bool put_star = !Dependencies::is_concrete_klass(witness);
833 st->print_cr(" witness = %s%s",
834 (put_star? "*": ""),
835 witness->external_name());
836 }
837 }
838
839 void Dependencies::DepStream::log_dependency(Klass* witness) {
840 if (_deps == nullptr && xtty == nullptr) return; // fast cutout for runtime
841 ResourceMark rm;
842 const int nargs = argument_count();
843 GrowableArray<DepArgument>* args = new GrowableArray<DepArgument>(nargs);
844 for (int j = 0; j < nargs; j++) {
845 if (is_oop_argument(j)) {
846 args->push(argument_oop(j));
847 } else {
848 args->push(argument(j));
849 }
850 }
851 int argslen = args->length();
852 if (_deps != nullptr && _deps->log() != nullptr) {
853 if (ciEnv::current() != nullptr) {
854 Dependencies::write_dependency_to(_deps->log(), type(), args, witness);
855 } else {
856 // Treat the CompileLog as an xmlstream instead
857 Dependencies::write_dependency_to((xmlStream*)_deps->log(), type(), args, witness);
858 }
859 } else {
860 Dependencies::write_dependency_to(xtty, type(), args, witness);
861 }
862 guarantee(argslen == args->length(), "args array cannot grow inside nested ResoureMark scope");
863 }
864
865 void Dependencies::DepStream::print_dependency(outputStream* st, Klass* witness, bool verbose) {
866 ResourceMark rm;
867 int nargs = argument_count();
868 GrowableArray<DepArgument>* args = new GrowableArray<DepArgument>(nargs);
869 for (int j = 0; j < nargs; j++) {
870 if (is_oop_argument(j)) {
871 args->push(argument_oop(j));
872 } else {
873 args->push(argument(j));
874 }
875 }
876 int argslen = args->length();
877 Dependencies::print_dependency(type(), args, witness, st);
878 if (verbose) {
879 if (_code != nullptr) {
880 st->print(" code: ");
881 _code->print_value_on(st);
882 st->cr();
883 }
884 }
885 guarantee(argslen == args->length(), "args array cannot grow inside nested ResoureMark scope");
886 }
887
888
889 /// Dependency stream support (decodes dependencies from an nmethod):
890
891 #ifdef ASSERT
892 void Dependencies::DepStream::initial_asserts(size_t byte_limit) {
893 assert(must_be_in_vm(), "raw oops here");
894 _byte_limit = byte_limit;
895 _type = undefined_dependency; // defeat "already at end" assert
896 assert((_code!=nullptr) + (_deps!=nullptr) == 1, "one or t'other");
897 }
898 #endif //ASSERT
899
900 bool Dependencies::DepStream::next() {
901 assert(_type != end_marker, "already at end");
902 if (_bytes.position() == 0 && _code != nullptr
903 && _code->dependencies_size() == 0) {
904 // Method has no dependencies at all.
905 return false;
906 }
907 int code_byte = (_bytes.read_byte() & 0xFF);
908 if (code_byte == end_marker) {
909 DEBUG_ONLY(_type = end_marker);
910 return false;
911 } else {
912 int ctxk_bit = (code_byte & Dependencies::default_context_type_bit);
913 code_byte -= ctxk_bit;
914 DepType dept = (DepType)code_byte;
915 _type = dept;
916 Dependencies::check_valid_dependency_type(dept);
917 int stride = _dep_args[dept];
918 assert(stride == dep_args(dept), "sanity");
919 int skipj = -1;
920 if (ctxk_bit != 0) {
921 skipj = 0; // currently the only context argument is at zero
922 assert(skipj == dep_context_arg(dept), "zero arg always ctxk");
923 }
924 for (int j = 0; j < stride; j++) {
925 _xi[j] = (j == skipj)? 0: _bytes.read_int();
926 }
927 DEBUG_ONLY(_xi[stride] = -1); // help detect overruns
928 return true;
929 }
930 }
931
932 inline Metadata* Dependencies::DepStream::recorded_metadata_at(int i) {
933 Metadata* o = nullptr;
934 if (_code != nullptr) {
935 o = _code->metadata_at(i);
936 } else {
937 o = _deps->oop_recorder()->metadata_at(i);
938 }
939 return o;
940 }
941
942 inline oop Dependencies::DepStream::recorded_oop_at(int i) {
943 return (_code != nullptr)
944 ? _code->oop_at(i)
945 : JNIHandles::resolve(_deps->oop_recorder()->oop_at(i));
946 }
947
948 Metadata* Dependencies::DepStream::argument(int i) {
949 Metadata* result = recorded_metadata_at(argument_index(i));
950
951 if (result == nullptr) { // Explicit context argument can be compressed
952 int ctxkj = dep_context_arg(type()); // -1 if no explicit context arg
953 if (ctxkj >= 0 && i == ctxkj && ctxkj+1 < argument_count()) {
954 result = ctxk_encoded_as_null(type(), argument(ctxkj+1));
955 }
956 }
957
958 assert(result == nullptr || result->is_klass() || result->is_method(), "must be");
959 return result;
960 }
961
962 /**
963 * Returns a unique identifier for each dependency argument.
964 */
965 uintptr_t Dependencies::DepStream::get_identifier(int i) {
966 if (is_oop_argument(i)) {
967 return (uintptr_t)(oopDesc*)argument_oop(i);
968 } else {
969 return (uintptr_t)argument(i);
970 }
971 }
972
973 oop Dependencies::DepStream::argument_oop(int i) {
974 oop result = recorded_oop_at(argument_index(i));
975 assert(oopDesc::is_oop_or_null(result), "must be");
976 return result;
977 }
978
979 InstanceKlass* Dependencies::DepStream::context_type() {
980 assert(must_be_in_vm(), "raw oops here");
981
982 // Most dependencies have an explicit context type argument.
983 {
984 int ctxkj = dep_context_arg(type()); // -1 if no explicit context arg
985 if (ctxkj >= 0) {
986 Metadata* k = argument(ctxkj);
987 assert(k != nullptr && k->is_klass(), "type check");
988 return InstanceKlass::cast((Klass*)k);
989 }
990 }
991
992 // Some dependencies are using the klass of the first object
993 // argument as implicit context type.
994 {
995 int ctxkj = dep_implicit_context_arg(type());
996 if (ctxkj >= 0) {
997 Klass* k = argument_oop(ctxkj)->klass();
998 assert(k != nullptr, "type check");
999 return InstanceKlass::cast(k);
1000 }
1001 }
1002
1003 // And some dependencies don't have a context type at all,
1004 // e.g. evol_method.
1005 return nullptr;
1006 }
1007
1008 // ----------------- DependencySignature --------------------------------------
1009 bool DependencySignature::equals(DependencySignature const& s1, DependencySignature const& s2) {
1010 if ((s1.type() != s2.type()) || (s1.args_count() != s2.args_count())) {
1011 return false;
1012 }
1013
1014 for (int i = 0; i < s1.args_count(); i++) {
1015 if (s1.arg(i) != s2.arg(i)) {
1016 return false;
1017 }
1018 }
1019 return true;
1020 }
1021
1022 /// Checking dependencies
1023
1024 // This hierarchy walker inspects subtypes of a given type, trying to find a "bad" class which breaks a dependency.
1025 // Such a class is called a "witness" to the broken dependency.
1026 // While searching around, we ignore "participants", which are already known to the dependency.
1027 class AbstractClassHierarchyWalker {
1028 public:
1029 enum { PARTICIPANT_LIMIT = 3 };
1030
1031 private:
1032 // if non-zero, tells how many witnesses to convert to participants
1033 uint _record_witnesses;
1034
1035 // special classes which are not allowed to be witnesses:
1036 Klass* _participants[PARTICIPANT_LIMIT+1];
1037 uint _num_participants;
1038
1039 #ifdef ASSERT
1040 uint _nof_requests; // one-shot walker
1041 #endif // ASSERT
1042
1043 static PerfCounter* _perf_find_witness_anywhere_calls_count;
1044 static PerfCounter* _perf_find_witness_anywhere_steps_count;
1045 static PerfCounter* _perf_find_witness_in_calls_count;
1046
1047 protected:
1048 virtual Klass* find_witness_in(KlassDepChange& changes) = 0;
1049 virtual Klass* find_witness_anywhere(InstanceKlass* context_type) = 0;
1050
1051 AbstractClassHierarchyWalker(Klass* participant) : _record_witnesses(0), _num_participants(0)
1052 #ifdef ASSERT
1053 , _nof_requests(0)
1054 #endif // ASSERT
1055 {
1056 for (uint i = 0; i < PARTICIPANT_LIMIT+1; i++) {
1057 _participants[i] = nullptr;
1058 }
1059 if (participant != nullptr) {
1060 add_participant(participant);
1061 }
1062 }
1063
1064 bool is_participant(Klass* k) {
1065 for (uint i = 0; i < _num_participants; i++) {
1066 if (_participants[i] == k) {
1067 return true;
1068 }
1069 }
1070 return false;
1071 }
1072
1073 bool record_witness(Klass* witness) {
1074 if (_record_witnesses > 0) {
1075 --_record_witnesses;
1076 add_participant(witness);
1077 return false; // not a witness
1078 } else {
1079 return true; // is a witness
1080 }
1081 }
1082
1083 class CountingClassHierarchyIterator : public ClassHierarchyIterator {
1084 private:
1085 jlong _nof_steps;
1086 public:
1087 CountingClassHierarchyIterator(InstanceKlass* root) : ClassHierarchyIterator(root), _nof_steps(0) {}
1088
1089 void next() {
1090 _nof_steps++;
1091 ClassHierarchyIterator::next();
1092 }
1093
1094 ~CountingClassHierarchyIterator() {
1095 if (UsePerfData) {
1096 _perf_find_witness_anywhere_steps_count->inc(_nof_steps);
1097 }
1098 }
1099 };
1100
1101 public:
1102 uint num_participants() { return _num_participants; }
1103 Klass* participant(uint n) {
1104 assert(n <= _num_participants, "oob");
1105 if (n < _num_participants) {
1106 return _participants[n];
1107 } else {
1108 return nullptr;
1109 }
1110 }
1111
1112 void add_participant(Klass* participant) {
1113 assert(!is_participant(participant), "sanity");
1114 assert(_num_participants + _record_witnesses < PARTICIPANT_LIMIT, "oob");
1115 uint np = _num_participants++;
1116 _participants[np] = participant;
1117 }
1118
1119 void record_witnesses(uint add) {
1120 if (add > PARTICIPANT_LIMIT) add = PARTICIPANT_LIMIT;
1121 assert(_num_participants + add < PARTICIPANT_LIMIT, "oob");
1122 _record_witnesses = add;
1123 }
1124
1125 Klass* find_witness(InstanceKlass* context_type, KlassDepChange* changes = nullptr);
1126
1127 static void init();
1128 static void print_statistics();
1129 };
1130
1131 PerfCounter* AbstractClassHierarchyWalker::_perf_find_witness_anywhere_calls_count = nullptr;
1132 PerfCounter* AbstractClassHierarchyWalker::_perf_find_witness_anywhere_steps_count = nullptr;
1133 PerfCounter* AbstractClassHierarchyWalker::_perf_find_witness_in_calls_count = nullptr;
1134
1135 void AbstractClassHierarchyWalker::init() {
1136 if (UsePerfData) {
1137 EXCEPTION_MARK;
1138 _perf_find_witness_anywhere_calls_count =
1139 PerfDataManager::create_counter(SUN_CI, "findWitnessAnywhere", PerfData::U_Events, CHECK);
1140 _perf_find_witness_anywhere_steps_count =
1141 PerfDataManager::create_counter(SUN_CI, "findWitnessAnywhereSteps", PerfData::U_Events, CHECK);
1142 _perf_find_witness_in_calls_count =
1143 PerfDataManager::create_counter(SUN_CI, "findWitnessIn", PerfData::U_Events, CHECK);
1144 }
1145 }
1146
1147 Klass* AbstractClassHierarchyWalker::find_witness(InstanceKlass* context_type, KlassDepChange* changes) {
1148 // Current thread must be in VM (not native mode, as in CI):
1149 assert(must_be_in_vm(), "raw oops here");
1150 // Must not move the class hierarchy during this check:
1151 assert_locked_or_safepoint(Compile_lock);
1152 assert(_nof_requests++ == 0, "repeated requests are not supported");
1153
1154 assert(changes == nullptr || changes->involves_context(context_type), "irrelevant dependency");
1155
1156 // (Note: Interfaces do not have subclasses.)
1157 // If it is an interface, search its direct implementors.
1158 // (Their subclasses are additional indirect implementors. See InstanceKlass::add_implementor().)
1159 if (context_type->is_interface()) {
1160 int nof_impls = context_type->nof_implementors();
1161 if (nof_impls == 0) {
1162 return nullptr; // no implementors
1163 } else if (nof_impls == 1) { // unique implementor
1164 assert(context_type != context_type->implementor(), "not unique");
1165 context_type = context_type->implementor();
1166 } else { // nof_impls >= 2
1167 // Avoid this case: *I.m > { A.m, C }; B.m > C
1168 // Here, I.m has 2 concrete implementations, but m appears unique
1169 // as A.m, because the search misses B.m when checking C.
1170 // The inherited method B.m was getting missed by the walker
1171 // when interface 'I' was the starting point.
1172 // %%% Until this is fixed more systematically, bail out.
1173 return context_type;
1174 }
1175 }
1176 assert(!context_type->is_interface(), "no interfaces allowed");
1177
1178 if (changes != nullptr) {
1179 if (UsePerfData) {
1180 _perf_find_witness_in_calls_count->inc();
1181 }
1182 return find_witness_in(*changes);
1183 } else {
1184 if (UsePerfData) {
1185 _perf_find_witness_anywhere_calls_count->inc();
1186 }
1187 return find_witness_anywhere(context_type);
1188 }
1189 }
1190
1191 class ConcreteSubtypeFinder : public AbstractClassHierarchyWalker {
1192 private:
1193 bool is_witness(Klass* k);
1194
1195 protected:
1196 virtual Klass* find_witness_in(KlassDepChange& changes);
1197 virtual Klass* find_witness_anywhere(InstanceKlass* context_type);
1198
1199 public:
1200 ConcreteSubtypeFinder(Klass* participant = nullptr) : AbstractClassHierarchyWalker(participant) {}
1201 };
1202
1203 bool ConcreteSubtypeFinder::is_witness(Klass* k) {
1204 if (Dependencies::is_concrete_klass(k)) {
1205 return record_witness(k); // concrete subtype
1206 } else {
1207 return false; // not a concrete class
1208 }
1209 }
1210
1211 Klass* ConcreteSubtypeFinder::find_witness_in(KlassDepChange& changes) {
1212 // When looking for unexpected concrete types, do not look beneath expected ones:
1213 // * CX > CC > C' is OK, even if C' is new.
1214 // * CX > { CC, C' } is not OK if C' is new, and C' is the witness.
1215 Klass* new_type = changes.as_new_klass_change()->new_type();
1216 assert(!is_participant(new_type), "only old classes are participants");
1217 // If the new type is a subtype of a participant, we are done.
1218 for (uint i = 0; i < num_participants(); i++) {
1219 if (changes.involves_context(participant(i))) {
1220 // new guy is protected from this check by previous participant
1221 return nullptr;
1222 }
1223 }
1224 if (is_witness(new_type)) {
1225 return new_type;
1226 }
1227 // No witness found. The dependency remains unbroken.
1228 return nullptr;
1229 }
1230
1231 Klass* ConcreteSubtypeFinder::find_witness_anywhere(InstanceKlass* context_type) {
1232 for (CountingClassHierarchyIterator iter(context_type); !iter.done(); iter.next()) {
1233 Klass* sub = iter.klass();
1234 // Do not report participant types.
1235 if (is_participant(sub)) {
1236 // Don't walk beneath a participant since it hides witnesses.
1237 iter.skip_subclasses();
1238 } else if (is_witness(sub)) {
1239 return sub; // found a witness
1240 }
1241 }
1242 // No witness found. The dependency remains unbroken.
1243 return nullptr;
1244 }
1245
1246 class ConcreteMethodFinder : public AbstractClassHierarchyWalker {
1247 private:
1248 Symbol* _name;
1249 Symbol* _signature;
1250
1251 // cache of method lookups
1252 Method* _found_methods[PARTICIPANT_LIMIT+1];
1253
1254 bool is_witness(Klass* k);
1255
1256 protected:
1257 virtual Klass* find_witness_in(KlassDepChange& changes);
1258 virtual Klass* find_witness_anywhere(InstanceKlass* context_type);
1259
1260 public:
1261 bool witnessed_reabstraction_in_supers(Klass* k);
1262
1263 ConcreteMethodFinder(Method* m, Klass* participant = nullptr) : AbstractClassHierarchyWalker(participant) {
1264 assert(m != nullptr && m->is_method(), "sanity");
1265 _name = m->name();
1266 _signature = m->signature();
1267
1268 for (int i = 0; i < PARTICIPANT_LIMIT+1; i++) {
1269 _found_methods[i] = nullptr;
1270 }
1271 }
1272
1273 // Note: If n==num_participants, returns nullptr.
1274 Method* found_method(uint n) {
1275 assert(n <= num_participants(), "oob");
1276 Method* fm = _found_methods[n];
1277 assert(n == num_participants() || fm != nullptr, "proper usage");
1278 if (fm != nullptr && fm->method_holder() != participant(n)) {
1279 // Default methods from interfaces can be added to classes. In
1280 // that case the holder of the method is not the class but the
1281 // interface where it's defined.
1282 assert(fm->is_default_method(), "sanity");
1283 return nullptr;
1284 }
1285 return fm;
1286 }
1287
1288 void add_participant(Klass* participant) {
1289 AbstractClassHierarchyWalker::add_participant(participant);
1290 _found_methods[num_participants()] = nullptr;
1291 }
1292
1293 bool record_witness(Klass* witness, Method* m) {
1294 _found_methods[num_participants()] = m;
1295 return AbstractClassHierarchyWalker::record_witness(witness);
1296 }
1297
1298 private:
1299 static PerfCounter* _perf_find_witness_anywhere_calls_count;
1300 static PerfCounter* _perf_find_witness_anywhere_steps_count;
1301 static PerfCounter* _perf_find_witness_in_calls_count;
1302
1303 public:
1304 static void init();
1305 static void print_statistics();
1306 };
1307
1308 bool ConcreteMethodFinder::is_witness(Klass* k) {
1309 if (is_participant(k)) {
1310 return false; // do not report participant types
1311 }
1312 if (k->is_instance_klass()) {
1313 InstanceKlass* ik = InstanceKlass::cast(k);
1314 // Search class hierarchy first, skipping private implementations
1315 // as they never override any inherited methods
1316 Method* m = ik->find_instance_method(_name, _signature, Klass::PrivateLookupMode::skip);
1317 if (Dependencies::is_concrete_method(m, ik)) {
1318 return record_witness(k, m); // concrete method found
1319 } else {
1320 // Check for re-abstraction of method
1321 if (!ik->is_interface() && m != nullptr && m->is_abstract()) {
1322 // Found a matching abstract method 'm' in the class hierarchy.
1323 // This is fine iff 'k' is an abstract class and all concrete subtypes
1324 // of 'k' override 'm' and are participates of the current search.
1325 ConcreteSubtypeFinder wf;
1326 for (uint i = 0; i < num_participants(); i++) {
1327 Klass* p = participant(i);
1328 wf.add_participant(p);
1329 }
1330 Klass* w = wf.find_witness(ik);
1331 if (w != nullptr) {
1332 Method* wm = InstanceKlass::cast(w)->find_instance_method(_name, _signature, Klass::PrivateLookupMode::skip);
1333 if (!Dependencies::is_concrete_method(wm, w)) {
1334 // Found a concrete subtype 'w' which does not override abstract method 'm'.
1335 // Bail out because 'm' could be called with 'w' as receiver (leading to an
1336 // AbstractMethodError) and thus the method we are looking for is not unique.
1337 return record_witness(k, m);
1338 }
1339 }
1340 }
1341 // Check interface defaults also, if any exist.
1342 Array<Method*>* default_methods = ik->default_methods();
1343 if (default_methods != nullptr) {
1344 Method* dm = ik->find_method(default_methods, _name, _signature);
1345 if (Dependencies::is_concrete_method(dm, nullptr)) {
1346 return record_witness(k, dm); // default method found
1347 }
1348 }
1349 return false; // no concrete method found
1350 }
1351 } else {
1352 return false; // no methods to find in an array type
1353 }
1354 }
1355
1356 Klass* ConcreteMethodFinder::find_witness_in(KlassDepChange& changes) {
1357 // When looking for unexpected concrete methods, look beneath expected ones, to see if there are overrides.
1358 // * CX.m > CC.m > C'.m is not OK, if C'.m is new, and C' is the witness.
1359 Klass* new_type = changes.as_new_klass_change()->new_type();
1360 assert(!is_participant(new_type), "only old classes are participants");
1361 if (is_witness(new_type)) {
1362 return new_type;
1363 } else {
1364 // No witness found, but is_witness() doesn't detect method re-abstraction in case of spot-checking.
1365 if (witnessed_reabstraction_in_supers(new_type)) {
1366 return new_type;
1367 }
1368 }
1369 // No witness found. The dependency remains unbroken.
1370 return nullptr;
1371 }
1372
1373 bool ConcreteMethodFinder::witnessed_reabstraction_in_supers(Klass* k) {
1374 if (!k->is_instance_klass()) {
1375 return false; // no methods to find in an array type
1376 } else {
1377 // Looking for a case when an abstract method is inherited into a concrete class.
1378 if (Dependencies::is_concrete_klass(k) && !k->is_interface()) {
1379 Method* m = InstanceKlass::cast(k)->find_instance_method(_name, _signature, Klass::PrivateLookupMode::skip);
1380 if (m != nullptr) {
1381 return false; // no reabstraction possible: local method found
1382 }
1383 for (InstanceKlass* super = k->java_super(); super != nullptr; super = super->java_super()) {
1384 m = super->find_instance_method(_name, _signature, Klass::PrivateLookupMode::skip);
1385 if (m != nullptr) { // inherited method found
1386 if (m->is_abstract() || m->is_overpass()) {
1387 return record_witness(super, m); // abstract method found
1388 }
1389 return false;
1390 }
1391 }
1392 // Miranda.
1393 return true;
1394 }
1395 return false;
1396 }
1397 }
1398
1399
1400 Klass* ConcreteMethodFinder::find_witness_anywhere(InstanceKlass* context_type) {
1401 // Walk hierarchy under a context type, looking for unexpected types.
1402 for (CountingClassHierarchyIterator iter(context_type); !iter.done(); iter.next()) {
1403 Klass* sub = iter.klass();
1404 if (is_witness(sub)) {
1405 return sub; // found a witness
1406 }
1407 }
1408 // No witness found. The dependency remains unbroken.
1409 return nullptr;
1410 }
1411
1412 // For some method m and some class ctxk (subclass of method holder),
1413 // enumerate all distinct overrides of m in concrete subclasses of ctxk.
1414 // It relies on vtable/itable information to perform method selection on each linked subclass
1415 // and ignores all non yet linked ones (speculatively treat them as "effectively abstract").
1416 class LinkedConcreteMethodFinder : public AbstractClassHierarchyWalker {
1417 private:
1418 InstanceKlass* _resolved_klass; // resolved class (JVMS-5.4.3.1)
1419 InstanceKlass* _declaring_klass; // the holder of resolved method (JVMS-5.4.3.3)
1420 int _vtable_index; // vtable/itable index of the resolved method
1421 bool _do_itable_lookup; // choose between itable and vtable lookup logic
1422
1423 // cache of method lookups
1424 Method* _found_methods[PARTICIPANT_LIMIT+1];
1425
1426 bool is_witness(Klass* k);
1427 Method* select_method(InstanceKlass* recv_klass);
1428 static int compute_vtable_index(InstanceKlass* resolved_klass, Method* resolved_method, bool& is_itable_index);
1429 static bool is_concrete_klass(InstanceKlass* ik);
1430
1431 void add_participant(Method* m, Klass* participant) {
1432 uint np = num_participants();
1433 AbstractClassHierarchyWalker::add_participant(participant);
1434 assert(np + 1 == num_participants(), "sanity");
1435 _found_methods[np] = m; // record the method for the participant
1436 }
1437
1438 bool record_witness(Klass* witness, Method* m) {
1439 for (uint i = 0; i < num_participants(); i++) {
1440 if (found_method(i) == m) {
1441 return false; // already recorded
1442 }
1443 }
1444 // Record not yet seen method.
1445 _found_methods[num_participants()] = m;
1446 return AbstractClassHierarchyWalker::record_witness(witness);
1447 }
1448
1449 void initialize(Method* participant) {
1450 for (uint i = 0; i < PARTICIPANT_LIMIT+1; i++) {
1451 _found_methods[i] = nullptr;
1452 }
1453 if (participant != nullptr) {
1454 add_participant(participant, participant->method_holder());
1455 }
1456 }
1457
1458 protected:
1459 virtual Klass* find_witness_in(KlassDepChange& changes);
1460 virtual Klass* find_witness_anywhere(InstanceKlass* context_type);
1461
1462 public:
1463 // In order to perform method selection, the following info is needed:
1464 // (1) interface or virtual call;
1465 // (2) vtable/itable index;
1466 // (3) declaring class (in case of interface call).
1467 //
1468 // It is prepared based on the results of method resolution: resolved class and resolved method (as specified in JVMS-5.4.3.3).
1469 // Optionally, a method which was previously determined as a unique target (uniqm) is added as a participant
1470 // to enable dependency spot-checking and speed up the search.
1471 LinkedConcreteMethodFinder(InstanceKlass* resolved_klass, Method* resolved_method, Method* uniqm = nullptr) : AbstractClassHierarchyWalker(nullptr) {
1472 assert(resolved_klass->is_linked(), "required");
1473 assert(resolved_method->method_holder()->is_linked(), "required");
1474 assert(!resolved_method->can_be_statically_bound(), "no vtable index available");
1475
1476 _resolved_klass = resolved_klass;
1477 _declaring_klass = resolved_method->method_holder();
1478 _vtable_index = compute_vtable_index(resolved_klass, resolved_method,
1479 _do_itable_lookup); // out parameter
1480 assert(_vtable_index >= 0, "invalid vtable index");
1481
1482 initialize(uniqm);
1483 }
1484
1485 // Note: If n==num_participants, returns nullptr.
1486 Method* found_method(uint n) {
1487 assert(n <= num_participants(), "oob");
1488 assert(participant(n) != nullptr || n == num_participants(), "proper usage");
1489 return _found_methods[n];
1490 }
1491 };
1492
1493 Klass* LinkedConcreteMethodFinder::find_witness_in(KlassDepChange& changes) {
1494 Klass* type = changes.type();
1495
1496 assert(!is_participant(type), "only old classes are participants");
1497
1498 if (is_witness(type)) {
1499 return type;
1500 }
1501 return nullptr; // No witness found. The dependency remains unbroken.
1502 }
1503
1504 Klass* LinkedConcreteMethodFinder::find_witness_anywhere(InstanceKlass* context_type) {
1505 for (CountingClassHierarchyIterator iter(context_type); !iter.done(); iter.next()) {
1506 Klass* sub = iter.klass();
1507 if (is_witness(sub)) {
1508 return sub;
1509 }
1510 if (sub->is_instance_klass() && !InstanceKlass::cast(sub)->is_linked()) {
1511 iter.skip_subclasses(); // ignore not yet linked classes
1512 }
1513 }
1514 return nullptr; // No witness found. The dependency remains unbroken.
1515 }
1516
1517 bool LinkedConcreteMethodFinder::is_witness(Klass* k) {
1518 if (is_participant(k)) {
1519 return false; // do not report participant types
1520 } else if (k->is_instance_klass()) {
1521 InstanceKlass* ik = InstanceKlass::cast(k);
1522 if (is_concrete_klass(ik)) {
1523 Method* m = select_method(ik);
1524 return record_witness(ik, m);
1525 } else {
1526 return false; // ignore non-concrete holder class
1527 }
1528 } else {
1529 return false; // no methods to find in an array type
1530 }
1531 }
1532
1533 Method* LinkedConcreteMethodFinder::select_method(InstanceKlass* recv_klass) {
1534 Method* selected_method = nullptr;
1535 if (_do_itable_lookup) {
1536 assert(_declaring_klass->is_interface(), "sanity");
1537 bool implements_interface; // initialized by method_at_itable_or_null()
1538 selected_method = recv_klass->method_at_itable_or_null(_declaring_klass, _vtable_index,
1539 implements_interface); // out parameter
1540 assert(implements_interface, "not implemented");
1541 } else {
1542 selected_method = recv_klass->method_at_vtable(_vtable_index);
1543 }
1544 return selected_method; // nullptr when corresponding slot is empty (AbstractMethodError case)
1545 }
1546
1547 int LinkedConcreteMethodFinder::compute_vtable_index(InstanceKlass* resolved_klass, Method* resolved_method,
1548 // out parameter
1549 bool& is_itable_index) {
1550 if (resolved_klass->is_interface() && resolved_method->has_itable_index()) {
1551 is_itable_index = true;
1552 return resolved_method->itable_index();
1553 }
1554 // Check for default or miranda method first.
1555 InstanceKlass* declaring_klass = resolved_method->method_holder();
1556 if (!resolved_klass->is_interface() && declaring_klass->is_interface()) {
1557 is_itable_index = false;
1558 return resolved_klass->vtable_index_of_interface_method(resolved_method);
1559 }
1560 // At this point we are sure that resolved_method is virtual and not
1561 // a default or miranda method; therefore, it must have a valid vtable index.
1562 assert(resolved_method->has_vtable_index(), "");
1563 is_itable_index = false;
1564 return resolved_method->vtable_index();
1565 }
1566
1567 bool LinkedConcreteMethodFinder::is_concrete_klass(InstanceKlass* ik) {
1568 if (!Dependencies::is_concrete_klass(ik)) {
1569 return false; // not concrete
1570 }
1571 if (ik->is_interface()) {
1572 return false; // interfaces aren't concrete
1573 }
1574 if (!ik->is_linked()) {
1575 return false; // not yet linked classes don't have instances
1576 }
1577 return true;
1578 }
1579
1580 #ifdef ASSERT
1581 // Assert that m is inherited into ctxk, without intervening overrides.
1582 // (May return true even if this is not true, in corner cases where we punt.)
1583 bool Dependencies::verify_method_context(InstanceKlass* ctxk, Method* m) {
1584 if (m->is_private()) {
1585 return false; // Quick lose. Should not happen.
1586 }
1587 if (m->method_holder() == ctxk) {
1588 return true; // Quick win.
1589 }
1590 if (!(m->is_public() || m->is_protected())) {
1591 // The override story is complex when packages get involved.
1592 return true; // Must punt the assertion to true.
1593 }
1594 Method* lm = ctxk->lookup_method(m->name(), m->signature());
1595 if (lm == nullptr) {
1596 // It might be an interface method
1597 lm = ctxk->lookup_method_in_ordered_interfaces(m->name(), m->signature());
1598 }
1599 if (lm == m) {
1600 // Method m is inherited into ctxk.
1601 return true;
1602 }
1603 if (lm != nullptr) {
1604 if (!(lm->is_public() || lm->is_protected())) {
1605 // Method is [package-]private, so the override story is complex.
1606 return true; // Must punt the assertion to true.
1607 }
1608 if (lm->is_static()) {
1609 // Static methods don't override non-static so punt
1610 return true;
1611 }
1612 if (!Dependencies::is_concrete_method(lm, ctxk) &&
1613 !Dependencies::is_concrete_method(m, ctxk)) {
1614 // They are both non-concrete
1615 if (lm->method_holder()->is_subtype_of(m->method_holder())) {
1616 // Method m is overridden by lm, but both are non-concrete.
1617 return true;
1618 }
1619 if (lm->method_holder()->is_interface() && m->method_holder()->is_interface() &&
1620 ctxk->is_subtype_of(m->method_holder()) && ctxk->is_subtype_of(lm->method_holder())) {
1621 // Interface method defined in multiple super interfaces
1622 return true;
1623 }
1624 }
1625 }
1626 ResourceMark rm;
1627 tty->print_cr("Dependency method not found in the associated context:");
1628 tty->print_cr(" context = %s", ctxk->external_name());
1629 tty->print( " method = "); m->print_short_name(tty); tty->cr();
1630 if (lm != nullptr) {
1631 tty->print( " found = "); lm->print_short_name(tty); tty->cr();
1632 }
1633 return false;
1634 }
1635 #endif // ASSERT
1636
1637 bool Dependencies::is_concrete_klass(Klass* k) {
1638 if (k->is_abstract()) return false;
1639 // %%% We could treat classes which are concrete but
1640 // have not yet been instantiated as virtually abstract.
1641 // This would require a deoptimization barrier on first instantiation.
1642 //if (k->is_not_instantiated()) return false;
1643 return true;
1644 }
1645
1646 bool Dependencies::is_concrete_method(Method* m, Klass* k) {
1647 // nullptr is not a concrete method.
1648 if (m == nullptr) {
1649 return false;
1650 }
1651 // Statics are irrelevant to virtual call sites.
1652 if (m->is_static()) {
1653 return false;
1654 }
1655 // Abstract methods are not concrete.
1656 if (m->is_abstract()) {
1657 return false;
1658 }
1659 // Overpass (error) methods are not concrete if k is abstract.
1660 if (m->is_overpass() && k != nullptr) {
1661 return !k->is_abstract();
1662 }
1663 // Note "true" is conservative answer: overpass clause is false if k == nullptr,
1664 // implies return true if answer depends on overpass clause.
1665 return true;
1666 }
1667
1668 Klass* Dependencies::find_finalizable_subclass(InstanceKlass* ik) {
1669 for (ClassHierarchyIterator iter(ik); !iter.done(); iter.next()) {
1670 Klass* sub = iter.klass();
1671 if (sub->has_finalizer() && !sub->is_interface()) {
1672 return sub;
1673 }
1674 }
1675 return nullptr; // not found
1676 }
1677
1678 bool Dependencies::is_concrete_klass(ciInstanceKlass* k) {
1679 if (k->is_abstract()) return false;
1680 // We could also return false if k does not yet appear to be
1681 // instantiated, if the VM version supports this distinction also.
1682 //if (k->is_not_instantiated()) return false;
1683 return true;
1684 }
1685
1686 bool Dependencies::has_finalizable_subclass(ciInstanceKlass* k) {
1687 return k->has_finalizable_subclass();
1688 }
1689
1690 // Any use of the contents (bytecodes) of a method must be
1691 // marked by an "evol_method" dependency, if those contents
1692 // can change. (Note: A method is always dependent on itself.)
1693 Klass* Dependencies::check_evol_method(Method* m) {
1694 assert(must_be_in_vm(), "raw oops here");
1695 // Did somebody do a JVMTI RedefineClasses while our backs were turned?
1696 // Or is there a now a breakpoint?
1697 // (Assumes compiled code cannot handle bkpts; change if UseFastBreakpoints.)
1698 if (m->is_old()
1699 || m->number_of_breakpoints() > 0
1700 || m->mismatch()) {
1701 return m->method_holder();
1702 } else {
1703 return nullptr;
1704 }
1705 }
1706
1707 // This is a strong assertion: It is that the given type
1708 // has no subtypes whatever. It is most useful for
1709 // optimizing checks on reflected types or on array types.
1710 // (Checks on types which are derived from real instances
1711 // can be optimized more strongly than this, because we
1712 // know that the checked type comes from a concrete type,
1713 // and therefore we can disregard abstract types.)
1714 Klass* Dependencies::check_leaf_type(InstanceKlass* ctxk) {
1715 assert(must_be_in_vm(), "raw oops here");
1716 assert_locked_or_safepoint(Compile_lock);
1717 Klass* sub = ctxk->subklass();
1718 if (sub != nullptr) {
1719 return sub;
1720 } else if (ctxk->nof_implementors() != 0) {
1721 // if it is an interface, it must be unimplemented
1722 // (if it is not an interface, nof_implementors is always zero)
1723 InstanceKlass* impl = ctxk->implementor();
1724 assert(impl != nullptr, "must be set");
1725 return impl;
1726 } else {
1727 return nullptr;
1728 }
1729 }
1730
1731 // Test the assertion that conck is the only concrete subtype* of ctxk.
1732 // The type conck itself is allowed to have have further concrete subtypes.
1733 // This allows the compiler to narrow occurrences of ctxk by conck,
1734 // when dealing with the types of actual instances.
1735 Klass* Dependencies::check_abstract_with_unique_concrete_subtype(InstanceKlass* ctxk,
1736 Klass* conck,
1737 NewKlassDepChange* changes) {
1738 ConcreteSubtypeFinder wf(conck);
1739 Klass* k = wf.find_witness(ctxk, changes);
1740 return k;
1741 }
1742
1743
1744 // Find the unique concrete proper subtype of ctxk, or nullptr if there
1745 // is more than one concrete proper subtype. If there are no concrete
1746 // proper subtypes, return ctxk itself, whether it is concrete or not.
1747 // The returned subtype is allowed to have have further concrete subtypes.
1748 // That is, return CC1 for CX > CC1 > CC2, but nullptr for CX > { CC1, CC2 }.
1749 Klass* Dependencies::find_unique_concrete_subtype(InstanceKlass* ctxk) {
1750 ConcreteSubtypeFinder wf(ctxk); // Ignore ctxk when walking.
1751 wf.record_witnesses(1); // Record one other witness when walking.
1752 Klass* wit = wf.find_witness(ctxk);
1753 if (wit != nullptr) return nullptr; // Too many witnesses.
1754 Klass* conck = wf.participant(0);
1755 if (conck == nullptr) {
1756 return ctxk; // Return ctxk as a flag for "no subtypes".
1757 } else {
1758 #ifndef PRODUCT
1759 // Make sure the dependency mechanism will pass this discovery:
1760 if (VerifyDependencies) {
1761 // Turn off dependency tracing while actually testing deps.
1762 FlagSetting fs(_verify_in_progress, true);
1763 if (!Dependencies::is_concrete_klass(ctxk)) {
1764 guarantee(nullptr == (void *)
1765 check_abstract_with_unique_concrete_subtype(ctxk, conck),
1766 "verify dep.");
1767 }
1768 }
1769 #endif //PRODUCT
1770 return conck;
1771 }
1772 }
1773
1774 // Try to determine whether root method in some context is concrete or not based on the information about the unique method
1775 // in that context. It exploits the fact that concrete root method is always inherited into the context when there's a unique method.
1776 // Hence, unique method holder is always a supertype of the context class when root method is concrete.
1777 // Examples for concrete_root_method
1778 // C (C.m uniqm)
1779 // |
1780 // CX (ctxk) uniqm is inherited into context.
1781 //
1782 // CX (ctxk) (CX.m uniqm) here uniqm is defined in ctxk.
1783 // Examples for !concrete_root_method
1784 // CX (ctxk)
1785 // |
1786 // C (C.m uniqm) uniqm is in subtype of ctxk.
1787 bool Dependencies::is_concrete_root_method(Method* uniqm, InstanceKlass* ctxk) {
1788 if (uniqm == nullptr) {
1789 return false; // match Dependencies::is_concrete_method() behavior
1790 }
1791 // Theoretically, the "direction" of subtype check matters here.
1792 // On one hand, in case of interface context with a single implementor, uniqm can be in a superclass of the implementor which
1793 // is not related to context class.
1794 // On another hand, uniqm could come from an interface unrelated to the context class, but right now it is not possible:
1795 // it is required that uniqm->method_holder() is the participant (uniqm->method_holder() <: ctxk), hence a default method
1796 // can't be used as unique.
1797 if (ctxk->is_interface()) {
1798 InstanceKlass* implementor = ctxk->implementor();
1799 assert(implementor != ctxk, "single implementor only"); // should have been invalidated earlier
1800 ctxk = implementor;
1801 }
1802 InstanceKlass* holder = uniqm->method_holder();
1803 assert(!holder->is_interface(), "no default methods allowed");
1804 assert(ctxk->is_subclass_of(holder) || holder->is_subclass_of(ctxk), "not related");
1805 return ctxk->is_subclass_of(holder);
1806 }
1807
1808 // If a class (or interface) has a unique concrete method uniqm, return nullptr.
1809 // Otherwise, return a class that contains an interfering method.
1810 Klass* Dependencies::check_unique_concrete_method(InstanceKlass* ctxk,
1811 Method* uniqm,
1812 NewKlassDepChange* changes) {
1813 ConcreteMethodFinder wf(uniqm, uniqm->method_holder());
1814 Klass* k = wf.find_witness(ctxk, changes);
1815 if (k != nullptr) {
1816 return k;
1817 }
1818 if (!Dependencies::is_concrete_root_method(uniqm, ctxk) || changes != nullptr) {
1819 Klass* conck = find_witness_AME(ctxk, uniqm, changes);
1820 if (conck != nullptr) {
1821 // Found a concrete subtype 'conck' which does not override abstract root method.
1822 return conck;
1823 }
1824 }
1825 return nullptr;
1826 }
1827
1828 Klass* Dependencies::check_unique_implementor(InstanceKlass* ctxk, Klass* uniqk, NewKlassDepChange* changes) {
1829 assert(ctxk->is_interface(), "sanity");
1830 assert(ctxk->nof_implementors() > 0, "no implementors");
1831 if (ctxk->nof_implementors() == 1) {
1832 assert(ctxk->implementor() == uniqk, "sanity");
1833 return nullptr;
1834 }
1835 return ctxk; // no unique implementor
1836 }
1837
1838 // Search for AME.
1839 // There are two version of checks.
1840 // 1) Spot checking version(Classload time). Newly added class is checked for AME.
1841 // Checks whether abstract/overpass method is inherited into/declared in newly added concrete class.
1842 // 2) Compile time analysis for abstract/overpass(abstract klass) root_m. The non uniqm subtrees are checked for concrete classes.
1843 Klass* Dependencies::find_witness_AME(InstanceKlass* ctxk, Method* m, KlassDepChange* changes) {
1844 if (m != nullptr) {
1845 if (changes != nullptr) {
1846 // Spot checking version.
1847 ConcreteMethodFinder wf(m);
1848 Klass* new_type = changes->as_new_klass_change()->new_type();
1849 if (wf.witnessed_reabstraction_in_supers(new_type)) {
1850 return new_type;
1851 }
1852 } else {
1853 // Note: It is required that uniqm->method_holder() is the participant (see ClassHierarchyWalker::found_method()).
1854 ConcreteSubtypeFinder wf(m->method_holder());
1855 Klass* conck = wf.find_witness(ctxk);
1856 if (conck != nullptr) {
1857 Method* cm = InstanceKlass::cast(conck)->find_instance_method(m->name(), m->signature(), Klass::PrivateLookupMode::skip);
1858 if (!Dependencies::is_concrete_method(cm, conck)) {
1859 return conck;
1860 }
1861 }
1862 }
1863 }
1864 return nullptr;
1865 }
1866
1867 // This function is used by find_unique_concrete_method(non vtable based)
1868 // to check whether subtype method overrides the base method.
1869 static bool overrides(Method* sub_m, Method* base_m) {
1870 assert(base_m != nullptr, "base method should be non null");
1871 if (sub_m == nullptr) {
1872 return false;
1873 }
1874 /**
1875 * If base_m is public or protected then sub_m always overrides.
1876 * If base_m is !public, !protected and !private (i.e. base_m is package private)
1877 * then sub_m should be in the same package as that of base_m.
1878 * For package private base_m this is conservative approach as it allows only subset of all allowed cases in
1879 * the jvm specification.
1880 **/
1881 if (base_m->is_public() || base_m->is_protected() ||
1882 base_m->method_holder()->is_same_class_package(sub_m->method_holder())) {
1883 return true;
1884 }
1885 return false;
1886 }
1887
1888 // Find the set of all non-abstract methods under ctxk that match m.
1889 // (The method m must be defined or inherited in ctxk.)
1890 // Include m itself in the set, unless it is abstract.
1891 // If this set has exactly one element, return that element.
1892 Method* Dependencies::find_unique_concrete_method(InstanceKlass* ctxk, Method* m, Klass** participant) {
1893 // Return nullptr if m is marked old; must have been a redefined method.
1894 if (m->is_old()) {
1895 return nullptr;
1896 }
1897 if (m->is_default_method()) {
1898 return nullptr; // not supported
1899 }
1900 assert(verify_method_context(ctxk, m), "proper context");
1901 ConcreteMethodFinder wf(m);
1902 wf.record_witnesses(1);
1903 Klass* wit = wf.find_witness(ctxk);
1904 if (wit != nullptr) return nullptr; // Too many witnesses.
1905 Method* fm = wf.found_method(0); // Will be nullptr if num_parts == 0.
1906 if (participant != nullptr) {
1907 (*participant) = wf.participant(0);
1908 }
1909 if (!Dependencies::is_concrete_method(fm, nullptr)) {
1910 fm = nullptr; // ignore abstract methods
1911 }
1912 if (Dependencies::is_concrete_method(m, ctxk)) {
1913 if (fm == nullptr) {
1914 // It turns out that m was always the only implementation.
1915 fm = m;
1916 } else if (fm != m) {
1917 // Two conflicting implementations after all.
1918 // (This can happen if m is inherited into ctxk and fm overrides it.)
1919 return nullptr;
1920 }
1921 } else if (Dependencies::find_witness_AME(ctxk, fm) != nullptr) {
1922 // Found a concrete subtype which does not override abstract root method.
1923 return nullptr;
1924 } else if (!overrides(fm, m)) {
1925 // Found method doesn't override abstract root method.
1926 return nullptr;
1927 }
1928 assert(Dependencies::is_concrete_root_method(fm, ctxk) == Dependencies::is_concrete_method(m, ctxk), "mismatch");
1929 #ifndef PRODUCT
1930 // Make sure the dependency mechanism will pass this discovery:
1931 if (VerifyDependencies && fm != nullptr) {
1932 guarantee(nullptr == (void *)check_unique_concrete_method(ctxk, fm),
1933 "verify dep.");
1934 }
1935 #endif //PRODUCT
1936 return fm;
1937 }
1938
1939 // If a class (or interface) has a unique concrete method uniqm, return nullptr.
1940 // Otherwise, return a class that contains an interfering method.
1941 Klass* Dependencies::check_unique_concrete_method(InstanceKlass* ctxk,
1942 Method* uniqm,
1943 Klass* resolved_klass,
1944 Method* resolved_method,
1945 KlassDepChange* changes) {
1946 assert(!ctxk->is_interface() || ctxk == resolved_klass, "sanity");
1947 assert(!resolved_method->can_be_statically_bound() || resolved_method == uniqm, "sanity");
1948 assert(resolved_klass->is_subtype_of(resolved_method->method_holder()), "sanity");
1949
1950 if (!InstanceKlass::cast(resolved_klass)->is_linked() ||
1951 !resolved_method->method_holder()->is_linked() ||
1952 resolved_method->can_be_statically_bound()) {
1953 // Dependency is redundant, but benign. Just keep it to avoid unnecessary recompilation.
1954 return nullptr; // no vtable index available
1955 }
1956
1957 LinkedConcreteMethodFinder mf(InstanceKlass::cast(resolved_klass), resolved_method, uniqm);
1958 return mf.find_witness(ctxk, changes);
1959 }
1960
1961 // Find the set of all non-abstract methods under ctxk that match m.
1962 // (The method m must be defined or inherited in ctxk.)
1963 // Include m itself in the set, unless it is abstract.
1964 // If this set has exactly one element, return that element.
1965 // Not yet linked subclasses of ctxk are ignored since they don't have any instances yet.
1966 // Additionally, resolved_klass and resolved_method complete the description of the call site being analyzed.
1967 Method* Dependencies::find_unique_concrete_method(InstanceKlass* ctxk, Method* m, Klass* resolved_klass, Method* resolved_method) {
1968 // Return nullptr if m is marked old; must have been a redefined method.
1969 if (m->is_old()) {
1970 return nullptr;
1971 }
1972 if (!InstanceKlass::cast(resolved_klass)->is_linked() ||
1973 !resolved_method->method_holder()->is_linked() ||
1974 resolved_method->can_be_statically_bound()) {
1975 return m; // nothing to do: no witness under ctxk
1976 }
1977 LinkedConcreteMethodFinder wf(InstanceKlass::cast(resolved_klass), resolved_method);
1978 assert(Dependencies::verify_method_context(ctxk, m), "proper context");
1979 wf.record_witnesses(1);
1980 Klass* wit = wf.find_witness(ctxk);
1981 if (wit != nullptr) {
1982 return nullptr; // Too many witnesses.
1983 }
1984 // p == nullptr when no participants are found (wf.num_participants() == 0).
1985 // fm == nullptr case has 2 meanings:
1986 // * when p == nullptr: no method found;
1987 // * when p != nullptr: AbstractMethodError-throwing method found.
1988 // Also, found method should always be accompanied by a participant class.
1989 Klass* p = wf.participant(0);
1990 Method* fm = wf.found_method(0);
1991 assert(fm == nullptr || p != nullptr, "no participant");
1992 // Normalize all error-throwing cases to nullptr.
1993 if (fm == Universe::throw_illegal_access_error() ||
1994 fm == Universe::throw_no_such_method_error() ||
1995 !Dependencies::is_concrete_method(fm, p)) {
1996 fm = nullptr; // error-throwing method
1997 }
1998 if (Dependencies::is_concrete_method(m, ctxk)) {
1999 if (p == nullptr) {
2000 // It turns out that m was always the only implementation.
2001 assert(fm == nullptr, "sanity");
2002 fm = m;
2003 }
2004 }
2005 #ifndef PRODUCT
2006 // Make sure the dependency mechanism will pass this discovery:
2007 if (VerifyDependencies && fm != nullptr) {
2008 guarantee(nullptr == check_unique_concrete_method(ctxk, fm, resolved_klass, resolved_method),
2009 "verify dep.");
2010 }
2011 #endif // PRODUCT
2012 assert(fm == nullptr || !fm->is_abstract(), "sanity");
2013 // Old CHA conservatively reports concrete methods in abstract classes
2014 // irrespective of whether they have concrete subclasses or not.
2015 // Also, abstract root method case is not fully supported.
2016 #ifdef ASSERT
2017 Klass* uniqp = nullptr;
2018 Method* uniqm = Dependencies::find_unique_concrete_method(ctxk, m, &uniqp);
2019 assert(uniqm == nullptr || uniqm == fm ||
2020 m->is_abstract() ||
2021 uniqm->method_holder()->is_abstract() ||
2022 (fm == nullptr && uniqm != nullptr && uniqp != nullptr && !InstanceKlass::cast(uniqp)->is_linked()),
2023 "sanity");
2024 #endif // ASSERT
2025 return fm;
2026 }
2027
2028 Klass* Dependencies::check_has_no_finalizable_subclasses(InstanceKlass* ctxk, NewKlassDepChange* changes) {
2029 InstanceKlass* search_at = ctxk;
2030 if (changes != nullptr) {
2031 search_at = changes->new_type(); // just look at the new bit
2032 }
2033 return find_finalizable_subclass(search_at);
2034 }
2035
2036 Klass* Dependencies::check_call_site_target_value(oop call_site, oop method_handle, CallSiteDepChange* changes) {
2037 assert(call_site != nullptr, "sanity");
2038 assert(method_handle != nullptr, "sanity");
2039 assert(call_site->is_a(vmClasses::CallSite_klass()), "sanity");
2040
2041 if (changes == nullptr) {
2042 // Validate all CallSites
2043 if (java_lang_invoke_CallSite::target(call_site) != method_handle)
2044 return call_site->klass(); // assertion failed
2045 } else {
2046 // Validate the given CallSite
2047 if (call_site == changes->call_site() && java_lang_invoke_CallSite::target(call_site) != changes->method_handle()) {
2048 assert(method_handle != changes->method_handle(), "must be");
2049 return call_site->klass(); // assertion failed
2050 }
2051 }
2052 return nullptr; // assertion still valid
2053 }
2054
2055 void Dependencies::DepStream::trace_and_log_witness(Klass* witness) {
2056 if (_verify_in_progress) return; // don't log
2057 if (witness != nullptr) {
2058 LogTarget(Debug, dependencies) lt;
2059 if (lt.is_enabled()) {
2060 LogStream ls(<);
2061 print_dependency(&ls, witness, /*verbose=*/ true);
2062 }
2063 // The following is a no-op unless logging is enabled:
2064 log_dependency(witness);
2065 }
2066 }
2067
2068 Klass* Dependencies::DepStream::check_new_klass_dependency(NewKlassDepChange* changes) {
2069 assert_locked_or_safepoint(Compile_lock);
2070 Dependencies::check_valid_dependency_type(type());
2071
2072 Klass* witness = nullptr;
2073 switch (type()) {
2074 case evol_method:
2075 witness = check_evol_method(method_argument(0));
2076 break;
2077 case leaf_type:
2078 witness = check_leaf_type(context_type());
2079 break;
2080 case abstract_with_unique_concrete_subtype:
2081 witness = check_abstract_with_unique_concrete_subtype(context_type(), type_argument(1), changes);
2082 break;
2083 case unique_concrete_method_2:
2084 witness = check_unique_concrete_method(context_type(), method_argument(1), changes);
2085 break;
2086 case unique_concrete_method_4:
2087 witness = check_unique_concrete_method(context_type(), method_argument(1), type_argument(2), method_argument(3), changes);
2088 break;
2089 case unique_implementor:
2090 witness = check_unique_implementor(context_type(), type_argument(1), changes);
2091 break;
2092 case no_finalizable_subclasses:
2093 witness = check_has_no_finalizable_subclasses(context_type(), changes);
2094 break;
2095 default:
2096 witness = nullptr;
2097 break;
2098 }
2099 trace_and_log_witness(witness);
2100 return witness;
2101 }
2102
2103 Klass* Dependencies::DepStream::check_klass_init_dependency(KlassInitDepChange* changes) {
2104 assert_locked_or_safepoint(Compile_lock);
2105 Dependencies::check_valid_dependency_type(type());
2106
2107 // No new types added. Only unique_concrete_method_4 is sensitive to class initialization changes.
2108 Klass* witness = nullptr;
2109 switch (type()) {
2110 case unique_concrete_method_4:
2111 witness = check_unique_concrete_method(context_type(), method_argument(1), type_argument(2), method_argument(3), changes);
2112 break;
2113 default:
2114 witness = nullptr;
2115 break;
2116 }
2117 trace_and_log_witness(witness);
2118 return witness;
2119 }
2120
2121 Klass* Dependencies::DepStream::check_klass_dependency(KlassDepChange* changes) {
2122 assert_locked_or_safepoint(Compile_lock);
2123 Dependencies::check_valid_dependency_type(type());
2124
2125 if (changes != nullptr) {
2126 if (changes->is_klass_init_change()) {
2127 return check_klass_init_dependency(changes->as_klass_init_change());
2128 } else {
2129 return check_new_klass_dependency(changes->as_new_klass_change());
2130 }
2131 } else {
2132 Klass* witness = check_new_klass_dependency(nullptr);
2133 // check_klass_init_dependency duplicates check_new_klass_dependency checks when class hierarchy change info is absent.
2134 assert(witness != nullptr || check_klass_init_dependency(nullptr) == nullptr, "missed dependency");
2135 return witness;
2136 }
2137 }
2138
2139 Klass* Dependencies::DepStream::check_call_site_dependency(CallSiteDepChange* changes) {
2140 assert_locked_or_safepoint(Compile_lock);
2141 Dependencies::check_valid_dependency_type(type());
2142
2143 Klass* witness = nullptr;
2144 switch (type()) {
2145 case call_site_target_value:
2146 witness = check_call_site_target_value(argument_oop(0), argument_oop(1), changes);
2147 break;
2148 default:
2149 witness = nullptr;
2150 break;
2151 }
2152 trace_and_log_witness(witness);
2153 return witness;
2154 }
2155
2156
2157 Klass* Dependencies::DepStream::spot_check_dependency_at(DepChange& changes) {
2158 // Handle klass dependency
2159 if (changes.is_klass_change() && changes.as_klass_change()->involves_context(context_type()))
2160 return check_klass_dependency(changes.as_klass_change());
2161
2162 // Handle CallSite dependency
2163 if (changes.is_call_site_change())
2164 return check_call_site_dependency(changes.as_call_site_change());
2165
2166 // irrelevant dependency; skip it
2167 return nullptr;
2168 }
2169
2170
2171 void DepChange::print() { print_on(tty); }
2172
2173 void DepChange::print_on(outputStream* st) {
2174 int nsup = 0, nint = 0;
2175 for (ContextStream str(*this); str.next(); ) {
2176 InstanceKlass* k = str.klass();
2177 switch (str.change_type()) {
2178 case Change_new_type:
2179 st->print_cr(" dependee = %s", k->external_name());
2180 break;
2181 case Change_new_sub:
2182 if (!WizardMode) {
2183 ++nsup;
2184 } else {
2185 st->print_cr(" context super = %s", k->external_name());
2186 }
2187 break;
2188 case Change_new_impl:
2189 if (!WizardMode) {
2190 ++nint;
2191 } else {
2192 st->print_cr(" context interface = %s", k->external_name());
2193 }
2194 break;
2195 default:
2196 break;
2197 }
2198 }
2199 if (nsup + nint != 0) {
2200 st->print_cr(" context supers = %d, interfaces = %d", nsup, nint);
2201 }
2202 }
2203
2204 void DepChange::ContextStream::start() {
2205 InstanceKlass* type = (_changes.is_klass_change() ? _changes.as_klass_change()->type() : (InstanceKlass*) nullptr);
2206 _change_type = (type == nullptr ? NO_CHANGE : Start_Klass);
2207 _klass = type;
2208 _ti_base = nullptr;
2209 _ti_index = 0;
2210 _ti_limit = 0;
2211 }
2212
2213 bool DepChange::ContextStream::next() {
2214 switch (_change_type) {
2215 case Start_Klass: // initial state; _klass is the new type
2216 _ti_base = _klass->transitive_interfaces();
2217 _ti_index = 0;
2218 _change_type = Change_new_type;
2219 return true;
2220 case Change_new_type:
2221 // fall through:
2222 _change_type = Change_new_sub;
2223 case Change_new_sub:
2224 // 6598190: brackets workaround Sun Studio C++ compiler bug 6629277
2225 {
2226 _klass = _klass->java_super();
2227 if (_klass != nullptr) {
2228 return true;
2229 }
2230 }
2231 // else set up _ti_limit and fall through:
2232 _ti_limit = (_ti_base == nullptr) ? 0 : _ti_base->length();
2233 _change_type = Change_new_impl;
2234 case Change_new_impl:
2235 if (_ti_index < _ti_limit) {
2236 _klass = _ti_base->at(_ti_index++);
2237 return true;
2238 }
2239 // fall through:
2240 _change_type = NO_CHANGE; // iterator is exhausted
2241 case NO_CHANGE:
2242 break;
2243 default:
2244 ShouldNotReachHere();
2245 }
2246 return false;
2247 }
2248
2249 void KlassDepChange::initialize() {
2250 // entire transaction must be under this lock:
2251 assert_lock_strong(Compile_lock);
2252
2253 // Mark all dependee and all its superclasses
2254 // Mark transitive interfaces
2255 for (ContextStream str(*this); str.next(); ) {
2256 InstanceKlass* d = str.klass();
2257 assert(!d->is_marked_dependent(), "checking");
2258 d->set_is_marked_dependent(true);
2259 }
2260 }
2261
2262 KlassDepChange::~KlassDepChange() {
2263 // Unmark all dependee and all its superclasses
2264 // Unmark transitive interfaces
2265 for (ContextStream str(*this); str.next(); ) {
2266 InstanceKlass* d = str.klass();
2267 d->set_is_marked_dependent(false);
2268 }
2269 }
2270
2271 bool KlassDepChange::involves_context(Klass* k) {
2272 if (k == nullptr || !k->is_instance_klass()) {
2273 return false;
2274 }
2275 InstanceKlass* ik = InstanceKlass::cast(k);
2276 bool is_contained = ik->is_marked_dependent();
2277 assert(is_contained == type()->is_subtype_of(k),
2278 "correct marking of potential context types");
2279 return is_contained;
2280 }
2281
2282 void Dependencies::print_statistics() {
2283 AbstractClassHierarchyWalker::print_statistics();
2284 }
2285
2286 void AbstractClassHierarchyWalker::print_statistics() {
2287 if (UsePerfData) {
2288 jlong deps_find_witness_calls = _perf_find_witness_anywhere_calls_count->get_value();
2289 jlong deps_find_witness_steps = _perf_find_witness_anywhere_steps_count->get_value();
2290 jlong deps_find_witness_singles = _perf_find_witness_in_calls_count->get_value();
2291
2292 ttyLocker ttyl;
2293 tty->print_cr("Dependency check (find_witness) "
2294 "calls=" JLONG_FORMAT ", steps=" JLONG_FORMAT " (avg=%.1f), singles=" JLONG_FORMAT,
2295 deps_find_witness_calls,
2296 deps_find_witness_steps,
2297 (double)deps_find_witness_steps / deps_find_witness_calls,
2298 deps_find_witness_singles);
2299 if (xtty != nullptr) {
2300 xtty->elem("deps_find_witness calls='" JLONG_FORMAT "' steps='" JLONG_FORMAT "' singles='" JLONG_FORMAT "'",
2301 deps_find_witness_calls,
2302 deps_find_witness_steps,
2303 deps_find_witness_singles);
2304 }
2305 }
2306 }
2307
2308 CallSiteDepChange::CallSiteDepChange(Handle call_site, Handle method_handle) :
2309 _call_site(call_site),
2310 _method_handle(method_handle) {
2311 assert(_call_site()->is_a(vmClasses::CallSite_klass()), "must be");
2312 assert(_method_handle.is_null() || _method_handle()->is_a(vmClasses::MethodHandle_klass()), "must be");
2313 }
2314
2315 void dependencies_init() {
2316 AbstractClassHierarchyWalker::init();
2317 }