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(" witness = %s%s",
834 (put_star ? "*": ""),
835 witness->external_name());
836 if (witness->is_instance_klass()) {
837 st->print(" (%s)", InstanceKlass::cast(witness)->init_state_name());
838 }
839 st->cr();
840 }
841 }
842
843 void Dependencies::DepStream::log_dependency(Klass* witness) {
844 if (_deps == nullptr && xtty == nullptr) return; // fast cutout for runtime
845 ResourceMark rm;
846 const int nargs = argument_count();
847 GrowableArray<DepArgument>* args = new GrowableArray<DepArgument>(nargs);
848 for (int j = 0; j < nargs; j++) {
849 if (is_oop_argument(j)) {
850 args->push(argument_oop(j));
851 } else {
852 args->push(argument(j));
853 }
854 }
855 int argslen = args->length();
856 if (_deps != nullptr && _deps->log() != nullptr) {
857 if (ciEnv::current() != nullptr) {
858 Dependencies::write_dependency_to(_deps->log(), type(), args, witness);
859 } else {
860 // Treat the CompileLog as an xmlstream instead
861 Dependencies::write_dependency_to((xmlStream*)_deps->log(), type(), args, witness);
862 }
863 } else {
864 Dependencies::write_dependency_to(xtty, type(), args, witness);
865 }
866 guarantee(argslen == args->length(), "args array cannot grow inside nested ResoureMark scope");
867 }
868
869 void Dependencies::DepStream::print_dependency(outputStream* st, Klass* witness, bool verbose) {
870 ResourceMark rm;
871 int nargs = argument_count();
872 GrowableArray<DepArgument>* args = new GrowableArray<DepArgument>(nargs);
873 for (int j = 0; j < nargs; j++) {
874 if (is_oop_argument(j)) {
875 args->push(argument_oop(j));
876 } else {
877 args->push(argument(j));
878 }
879 }
880 int argslen = args->length();
881 Dependencies::print_dependency(type(), args, witness, st);
882 if (verbose) {
883 if (_code != nullptr) {
884 st->print(" code: ");
885 _code->print_value_on(st);
886 st->cr();
887 }
888 }
889 guarantee(argslen == args->length(), "args array cannot grow inside nested ResoureMark scope");
890 }
891
892
893 /// Dependency stream support (decodes dependencies from an nmethod):
894
895 #ifdef ASSERT
896 void Dependencies::DepStream::initial_asserts(size_t byte_limit) {
897 assert(must_be_in_vm(), "raw oops here");
898 _byte_limit = byte_limit;
899 _type = undefined_dependency; // defeat "already at end" assert
900 assert((_code!=nullptr) + (_deps!=nullptr) == 1, "one or t'other");
901 }
902 #endif //ASSERT
903
904 bool Dependencies::DepStream::next() {
905 assert(_type != end_marker, "already at end");
906 if (_bytes.position() == 0 && _code != nullptr
907 && _code->dependencies_size() == 0) {
908 // Method has no dependencies at all.
909 return false;
910 }
911 int code_byte = (_bytes.read_byte() & 0xFF);
912 if (code_byte == end_marker) {
913 DEBUG_ONLY(_type = end_marker);
914 return false;
915 } else {
916 int ctxk_bit = (code_byte & Dependencies::default_context_type_bit);
917 code_byte -= ctxk_bit;
918 DepType dept = (DepType)code_byte;
919 _type = dept;
920 Dependencies::check_valid_dependency_type(dept);
921 int stride = _dep_args[dept];
922 assert(stride == dep_args(dept), "sanity");
923 int skipj = -1;
924 if (ctxk_bit != 0) {
925 skipj = 0; // currently the only context argument is at zero
926 assert(skipj == dep_context_arg(dept), "zero arg always ctxk");
927 }
928 for (int j = 0; j < stride; j++) {
929 _xi[j] = (j == skipj)? 0: _bytes.read_int();
930 }
931 DEBUG_ONLY(_xi[stride] = -1); // help detect overruns
932 return true;
933 }
934 }
935
936 inline Metadata* Dependencies::DepStream::recorded_metadata_at(int i) {
937 Metadata* o = nullptr;
938 if (_code != nullptr) {
939 o = _code->metadata_at(i);
940 } else {
941 o = _deps->oop_recorder()->metadata_at(i);
942 }
943 return o;
944 }
945
946 inline oop Dependencies::DepStream::recorded_oop_at(int i) {
947 return (_code != nullptr)
948 ? _code->oop_at(i)
949 : JNIHandles::resolve(_deps->oop_recorder()->oop_at(i));
950 }
951
952 Metadata* Dependencies::DepStream::argument(int i) {
953 Metadata* result = recorded_metadata_at(argument_index(i));
954
955 if (result == nullptr) { // Explicit context argument can be compressed
956 int ctxkj = dep_context_arg(type()); // -1 if no explicit context arg
957 if (ctxkj >= 0 && i == ctxkj && ctxkj+1 < argument_count()) {
958 result = ctxk_encoded_as_null(type(), argument(ctxkj+1));
959 }
960 }
961
962 assert(result == nullptr || result->is_klass() || result->is_method(), "must be");
963 return result;
964 }
965
966 /**
967 * Returns a unique identifier for each dependency argument.
968 */
969 uintptr_t Dependencies::DepStream::get_identifier(int i) {
970 if (is_oop_argument(i)) {
971 return (uintptr_t)(oopDesc*)argument_oop(i);
972 } else {
973 return (uintptr_t)argument(i);
974 }
975 }
976
977 oop Dependencies::DepStream::argument_oop(int i) {
978 oop result = recorded_oop_at(argument_index(i));
979 assert(oopDesc::is_oop_or_null(result), "must be");
980 return result;
981 }
982
983 InstanceKlass* Dependencies::DepStream::context_type() {
984 assert(must_be_in_vm(), "raw oops here");
985
986 // Most dependencies have an explicit context type argument.
987 {
988 int ctxkj = dep_context_arg(type()); // -1 if no explicit context arg
989 if (ctxkj >= 0) {
990 Metadata* k = argument(ctxkj);
991 assert(k != nullptr && k->is_klass(), "type check");
992 return InstanceKlass::cast((Klass*)k);
993 }
994 }
995
996 // Some dependencies are using the klass of the first object
997 // argument as implicit context type.
998 {
999 int ctxkj = dep_implicit_context_arg(type());
1000 if (ctxkj >= 0) {
1001 Klass* k = argument_oop(ctxkj)->klass();
1002 assert(k != nullptr, "type check");
1003 return InstanceKlass::cast(k);
1004 }
1005 }
1006
1007 // And some dependencies don't have a context type at all,
1008 // e.g. evol_method.
1009 return nullptr;
1010 }
1011
1012 // ----------------- DependencySignature --------------------------------------
1013 bool DependencySignature::equals(DependencySignature const& s1, DependencySignature const& s2) {
1014 if ((s1.type() != s2.type()) || (s1.args_count() != s2.args_count())) {
1015 return false;
1016 }
1017
1018 for (int i = 0; i < s1.args_count(); i++) {
1019 if (s1.arg(i) != s2.arg(i)) {
1020 return false;
1021 }
1022 }
1023 return true;
1024 }
1025
1026 /// Checking dependencies
1027
1028 // This hierarchy walker inspects subtypes of a given type, trying to find a "bad" class which breaks a dependency.
1029 // Such a class is called a "witness" to the broken dependency.
1030 // While searching around, we ignore "participants", which are already known to the dependency.
1031 class AbstractClassHierarchyWalker {
1032 public:
1033 enum { PARTICIPANT_LIMIT = 3 };
1034
1035 private:
1036 // if non-zero, tells how many witnesses to convert to participants
1037 uint _record_witnesses;
1038
1039 // special classes which are not allowed to be witnesses:
1040 Klass* _participants[PARTICIPANT_LIMIT+1];
1041 uint _num_participants;
1042
1043 #ifdef ASSERT
1044 uint _nof_requests; // one-shot walker
1045 #endif // ASSERT
1046
1047 static PerfCounter* _perf_find_witness_anywhere_calls_count;
1048 static PerfCounter* _perf_find_witness_anywhere_steps_count;
1049 static PerfCounter* _perf_find_witness_in_calls_count;
1050
1051 protected:
1052 virtual Klass* find_witness_in(KlassDepChange& changes) = 0;
1053 virtual Klass* find_witness_anywhere(InstanceKlass* context_type) = 0;
1054
1055 AbstractClassHierarchyWalker(Klass* participant) : _record_witnesses(0), _num_participants(0)
1056 #ifdef ASSERT
1057 , _nof_requests(0)
1058 #endif // ASSERT
1059 {
1060 for (uint i = 0; i < PARTICIPANT_LIMIT+1; i++) {
1061 _participants[i] = nullptr;
1062 }
1063 if (participant != nullptr) {
1064 add_participant(participant);
1065 }
1066 }
1067
1068 bool is_participant(Klass* k) {
1069 for (uint i = 0; i < _num_participants; i++) {
1070 if (_participants[i] == k) {
1071 return true;
1072 }
1073 }
1074 return false;
1075 }
1076
1077 bool record_witness(Klass* witness) {
1078 if (_record_witnesses > 0) {
1079 --_record_witnesses;
1080 add_participant(witness);
1081 return false; // not a witness
1082 } else {
1083 return true; // is a witness
1084 }
1085 }
1086
1087 class CountingClassHierarchyIterator : public ClassHierarchyIterator {
1088 private:
1089 jlong _nof_steps;
1090 public:
1091 CountingClassHierarchyIterator(InstanceKlass* root) : ClassHierarchyIterator(root), _nof_steps(0) {}
1092
1093 void next() {
1094 _nof_steps++;
1095 ClassHierarchyIterator::next();
1096 }
1097
1098 ~CountingClassHierarchyIterator() {
1099 if (UsePerfData) {
1100 _perf_find_witness_anywhere_steps_count->inc(_nof_steps);
1101 }
1102 }
1103 };
1104
1105 public:
1106 uint num_participants() { return _num_participants; }
1107 Klass* participant(uint n) {
1108 assert(n <= _num_participants, "oob");
1109 if (n < _num_participants) {
1110 return _participants[n];
1111 } else {
1112 return nullptr;
1113 }
1114 }
1115
1116 void add_participant(Klass* participant) {
1117 assert(!is_participant(participant), "sanity");
1118 assert(_num_participants + _record_witnesses < PARTICIPANT_LIMIT, "oob");
1119 uint np = _num_participants++;
1120 _participants[np] = participant;
1121 }
1122
1123 void record_witnesses(uint add) {
1124 if (add > PARTICIPANT_LIMIT) add = PARTICIPANT_LIMIT;
1125 assert(_num_participants + add < PARTICIPANT_LIMIT, "oob");
1126 _record_witnesses = add;
1127 }
1128
1129 Klass* find_witness(InstanceKlass* context_type, KlassDepChange* changes = nullptr);
1130
1131 static void init();
1132 static void print_statistics();
1133 };
1134
1135 PerfCounter* AbstractClassHierarchyWalker::_perf_find_witness_anywhere_calls_count = nullptr;
1136 PerfCounter* AbstractClassHierarchyWalker::_perf_find_witness_anywhere_steps_count = nullptr;
1137 PerfCounter* AbstractClassHierarchyWalker::_perf_find_witness_in_calls_count = nullptr;
1138
1139 void AbstractClassHierarchyWalker::init() {
1140 if (UsePerfData) {
1141 EXCEPTION_MARK;
1142 _perf_find_witness_anywhere_calls_count =
1143 PerfDataManager::create_counter(SUN_CI, "findWitnessAnywhere", PerfData::U_Events, CHECK);
1144 _perf_find_witness_anywhere_steps_count =
1145 PerfDataManager::create_counter(SUN_CI, "findWitnessAnywhereSteps", PerfData::U_Events, CHECK);
1146 _perf_find_witness_in_calls_count =
1147 PerfDataManager::create_counter(SUN_CI, "findWitnessIn", PerfData::U_Events, CHECK);
1148 }
1149 }
1150
1151 Klass* AbstractClassHierarchyWalker::find_witness(InstanceKlass* context_type, KlassDepChange* changes) {
1152 // Current thread must be in VM (not native mode, as in CI):
1153 assert(must_be_in_vm(), "raw oops here");
1154 // Must not move the class hierarchy during this check:
1155 assert_locked_or_safepoint(Compile_lock);
1156 assert(_nof_requests++ == 0, "repeated requests are not supported");
1157
1158 assert(changes == nullptr || changes->involves_context(context_type), "irrelevant dependency");
1159
1160 // (Note: Interfaces do not have subclasses.)
1161 // If it is an interface, search its direct implementors.
1162 // (Their subclasses are additional indirect implementors. See InstanceKlass::add_implementor().)
1163 if (context_type->is_interface()) {
1164 int nof_impls = context_type->nof_implementors();
1165 if (nof_impls == 0) {
1166 return nullptr; // no implementors
1167 } else if (nof_impls == 1) { // unique implementor
1168 assert(context_type != context_type->implementor(), "not unique");
1169 context_type = context_type->implementor();
1170 } else { // nof_impls >= 2
1171 // Avoid this case: *I.m > { A.m, C }; B.m > C
1172 // Here, I.m has 2 concrete implementations, but m appears unique
1173 // as A.m, because the search misses B.m when checking C.
1174 // The inherited method B.m was getting missed by the walker
1175 // when interface 'I' was the starting point.
1176 // %%% Until this is fixed more systematically, bail out.
1177 return context_type;
1178 }
1179 }
1180 assert(!context_type->is_interface(), "no interfaces allowed");
1181
1182 if (changes != nullptr) {
1183 if (UsePerfData) {
1184 _perf_find_witness_in_calls_count->inc();
1185 }
1186 return find_witness_in(*changes);
1187 } else {
1188 if (UsePerfData) {
1189 _perf_find_witness_anywhere_calls_count->inc();
1190 }
1191 return find_witness_anywhere(context_type);
1192 }
1193 }
1194
1195 class ConcreteSubtypeFinder : public AbstractClassHierarchyWalker {
1196 private:
1197 bool is_witness(Klass* k);
1198
1199 protected:
1200 virtual Klass* find_witness_in(KlassDepChange& changes);
1201 virtual Klass* find_witness_anywhere(InstanceKlass* context_type);
1202
1203 public:
1204 ConcreteSubtypeFinder(Klass* participant = nullptr) : AbstractClassHierarchyWalker(participant) {}
1205 };
1206
1207 bool ConcreteSubtypeFinder::is_witness(Klass* k) {
1208 if (Dependencies::is_concrete_klass(k)) {
1209 return record_witness(k); // concrete subtype
1210 } else {
1211 return false; // not a concrete class
1212 }
1213 }
1214
1215 Klass* ConcreteSubtypeFinder::find_witness_in(KlassDepChange& changes) {
1216 // When looking for unexpected concrete types, do not look beneath expected ones:
1217 // * CX > CC > C' is OK, even if C' is new.
1218 // * CX > { CC, C' } is not OK if C' is new, and C' is the witness.
1219 Klass* new_type = changes.as_new_klass_change()->new_type();
1220 assert(!is_participant(new_type), "only old classes are participants");
1221 // If the new type is a subtype of a participant, we are done.
1222 for (uint i = 0; i < num_participants(); i++) {
1223 if (changes.involves_context(participant(i))) {
1224 // new guy is protected from this check by previous participant
1225 return nullptr;
1226 }
1227 }
1228 if (is_witness(new_type)) {
1229 return new_type;
1230 }
1231 // No witness found. The dependency remains unbroken.
1232 return nullptr;
1233 }
1234
1235 Klass* ConcreteSubtypeFinder::find_witness_anywhere(InstanceKlass* context_type) {
1236 for (CountingClassHierarchyIterator iter(context_type); !iter.done(); iter.next()) {
1237 Klass* sub = iter.klass();
1238 // Do not report participant types.
1239 if (is_participant(sub)) {
1240 // Don't walk beneath a participant since it hides witnesses.
1241 iter.skip_subclasses();
1242 } else if (is_witness(sub)) {
1243 return sub; // found a witness
1244 }
1245 }
1246 // No witness found. The dependency remains unbroken.
1247 return nullptr;
1248 }
1249
1250 class ConcreteMethodFinder : public AbstractClassHierarchyWalker {
1251 private:
1252 Symbol* _name;
1253 Symbol* _signature;
1254
1255 // cache of method lookups
1256 Method* _found_methods[PARTICIPANT_LIMIT+1];
1257
1258 bool is_witness(Klass* k);
1259
1260 protected:
1261 virtual Klass* find_witness_in(KlassDepChange& changes);
1262 virtual Klass* find_witness_anywhere(InstanceKlass* context_type);
1263
1264 public:
1265 bool witnessed_reabstraction_in_supers(Klass* k);
1266
1267 ConcreteMethodFinder(Method* m, Klass* participant = nullptr) : AbstractClassHierarchyWalker(participant) {
1268 assert(m != nullptr && m->is_method(), "sanity");
1269 _name = m->name();
1270 _signature = m->signature();
1271
1272 for (int i = 0; i < PARTICIPANT_LIMIT+1; i++) {
1273 _found_methods[i] = nullptr;
1274 }
1275 }
1276
1277 // Note: If n==num_participants, returns nullptr.
1278 Method* found_method(uint n) {
1279 assert(n <= num_participants(), "oob");
1280 Method* fm = _found_methods[n];
1281 assert(n == num_participants() || fm != nullptr, "proper usage");
1282 if (fm != nullptr && fm->method_holder() != participant(n)) {
1283 // Default methods from interfaces can be added to classes. In
1284 // that case the holder of the method is not the class but the
1285 // interface where it's defined.
1286 assert(fm->is_default_method(), "sanity");
1287 return nullptr;
1288 }
1289 return fm;
1290 }
1291
1292 void add_participant(Klass* participant) {
1293 AbstractClassHierarchyWalker::add_participant(participant);
1294 _found_methods[num_participants()] = nullptr;
1295 }
1296
1297 bool record_witness(Klass* witness, Method* m) {
1298 _found_methods[num_participants()] = m;
1299 return AbstractClassHierarchyWalker::record_witness(witness);
1300 }
1301
1302 private:
1303 static PerfCounter* _perf_find_witness_anywhere_calls_count;
1304 static PerfCounter* _perf_find_witness_anywhere_steps_count;
1305 static PerfCounter* _perf_find_witness_in_calls_count;
1306
1307 public:
1308 static void init();
1309 static void print_statistics();
1310 };
1311
1312 bool ConcreteMethodFinder::is_witness(Klass* k) {
1313 if (is_participant(k)) {
1314 return false; // do not report participant types
1315 }
1316 if (k->is_instance_klass()) {
1317 InstanceKlass* ik = InstanceKlass::cast(k);
1318 // Search class hierarchy first, skipping private implementations
1319 // as they never override any inherited methods
1320 Method* m = ik->find_instance_method(_name, _signature, Klass::PrivateLookupMode::skip);
1321 if (Dependencies::is_concrete_method(m, ik)) {
1322 return record_witness(k, m); // concrete method found
1323 } else {
1324 // Check for re-abstraction of method
1325 if (!ik->is_interface() && m != nullptr && m->is_abstract()) {
1326 // Found a matching abstract method 'm' in the class hierarchy.
1327 // This is fine iff 'k' is an abstract class and all concrete subtypes
1328 // of 'k' override 'm' and are participates of the current search.
1329 ConcreteSubtypeFinder wf;
1330 for (uint i = 0; i < num_participants(); i++) {
1331 Klass* p = participant(i);
1332 wf.add_participant(p);
1333 }
1334 Klass* w = wf.find_witness(ik);
1335 if (w != nullptr) {
1336 Method* wm = InstanceKlass::cast(w)->find_instance_method(_name, _signature, Klass::PrivateLookupMode::skip);
1337 if (!Dependencies::is_concrete_method(wm, w)) {
1338 // Found a concrete subtype 'w' which does not override abstract method 'm'.
1339 // Bail out because 'm' could be called with 'w' as receiver (leading to an
1340 // AbstractMethodError) and thus the method we are looking for is not unique.
1341 return record_witness(k, m);
1342 }
1343 }
1344 }
1345 // Check interface defaults also, if any exist.
1346 Array<Method*>* default_methods = ik->default_methods();
1347 if (default_methods != nullptr) {
1348 Method* dm = ik->find_method(default_methods, _name, _signature);
1349 if (Dependencies::is_concrete_method(dm, nullptr)) {
1350 return record_witness(k, dm); // default method found
1351 }
1352 }
1353 return false; // no concrete method found
1354 }
1355 } else {
1356 return false; // no methods to find in an array type
1357 }
1358 }
1359
1360 Klass* ConcreteMethodFinder::find_witness_in(KlassDepChange& changes) {
1361 // When looking for unexpected concrete methods, look beneath expected ones, to see if there are overrides.
1362 // * CX.m > CC.m > C'.m is not OK, if C'.m is new, and C' is the witness.
1363 Klass* new_type = changes.as_new_klass_change()->new_type();
1364 assert(!is_participant(new_type), "only old classes are participants");
1365 if (is_witness(new_type)) {
1366 return new_type;
1367 } else {
1368 // No witness found, but is_witness() doesn't detect method re-abstraction in case of spot-checking.
1369 if (witnessed_reabstraction_in_supers(new_type)) {
1370 return new_type;
1371 }
1372 }
1373 // No witness found. The dependency remains unbroken.
1374 return nullptr;
1375 }
1376
1377 bool ConcreteMethodFinder::witnessed_reabstraction_in_supers(Klass* k) {
1378 if (!k->is_instance_klass()) {
1379 return false; // no methods to find in an array type
1380 } else {
1381 // Looking for a case when an abstract method is inherited into a concrete class.
1382 if (Dependencies::is_concrete_klass(k) && !k->is_interface()) {
1383 Method* m = InstanceKlass::cast(k)->find_instance_method(_name, _signature, Klass::PrivateLookupMode::skip);
1384 if (m != nullptr) {
1385 return false; // no reabstraction possible: local method found
1386 }
1387 for (InstanceKlass* super = k->java_super(); super != nullptr; super = super->java_super()) {
1388 m = super->find_instance_method(_name, _signature, Klass::PrivateLookupMode::skip);
1389 if (m != nullptr) { // inherited method found
1390 if (m->is_abstract() || m->is_overpass()) {
1391 return record_witness(super, m); // abstract method found
1392 }
1393 return false;
1394 }
1395 }
1396 // Miranda.
1397 return true;
1398 }
1399 return false;
1400 }
1401 }
1402
1403
1404 Klass* ConcreteMethodFinder::find_witness_anywhere(InstanceKlass* context_type) {
1405 // Walk hierarchy under a context type, looking for unexpected types.
1406 for (CountingClassHierarchyIterator iter(context_type); !iter.done(); iter.next()) {
1407 Klass* sub = iter.klass();
1408 if (is_witness(sub)) {
1409 return sub; // found a witness
1410 }
1411 }
1412 // No witness found. The dependency remains unbroken.
1413 return nullptr;
1414 }
1415
1416 // For some method m and some class ctxk (subclass of method holder),
1417 // enumerate all distinct overrides of m in concrete subclasses of ctxk.
1418 // It relies on vtable/itable information to perform method selection on each linked subclass
1419 // and ignores all non yet linked ones (speculatively treat them as "effectively abstract").
1420 class LinkedConcreteMethodFinder : public AbstractClassHierarchyWalker {
1421 private:
1422 InstanceKlass* _resolved_klass; // resolved class (JVMS-5.4.3.1)
1423 InstanceKlass* _declaring_klass; // the holder of resolved method (JVMS-5.4.3.3)
1424 int _vtable_index; // vtable/itable index of the resolved method
1425 bool _do_itable_lookup; // choose between itable and vtable lookup logic
1426
1427 // cache of method lookups
1428 Method* _found_methods[PARTICIPANT_LIMIT+1];
1429
1430 bool is_witness(Klass* k);
1431 Method* select_method(InstanceKlass* recv_klass);
1432 static int compute_vtable_index(InstanceKlass* resolved_klass, Method* resolved_method, bool& is_itable_index);
1433 static bool is_concrete_klass(InstanceKlass* ik);
1434
1435 void add_participant(Method* m, Klass* participant) {
1436 uint np = num_participants();
1437 AbstractClassHierarchyWalker::add_participant(participant);
1438 assert(np + 1 == num_participants(), "sanity");
1439 _found_methods[np] = m; // record the method for the participant
1440 }
1441
1442 bool record_witness(Klass* witness, Method* m) {
1443 for (uint i = 0; i < num_participants(); i++) {
1444 if (found_method(i) == m) {
1445 return false; // already recorded
1446 }
1447 }
1448 // Record not yet seen method.
1449 _found_methods[num_participants()] = m;
1450 return AbstractClassHierarchyWalker::record_witness(witness);
1451 }
1452
1453 void initialize(Method* participant) {
1454 for (uint i = 0; i < PARTICIPANT_LIMIT+1; i++) {
1455 _found_methods[i] = nullptr;
1456 }
1457 if (participant != nullptr) {
1458 add_participant(participant, participant->method_holder());
1459 }
1460 }
1461
1462 protected:
1463 virtual Klass* find_witness_in(KlassDepChange& changes);
1464 virtual Klass* find_witness_anywhere(InstanceKlass* context_type);
1465
1466 public:
1467 // In order to perform method selection, the following info is needed:
1468 // (1) interface or virtual call;
1469 // (2) vtable/itable index;
1470 // (3) declaring class (in case of interface call).
1471 //
1472 // It is prepared based on the results of method resolution: resolved class and resolved method (as specified in JVMS-5.4.3.3).
1473 // Optionally, a method which was previously determined as a unique target (uniqm) is added as a participant
1474 // to enable dependency spot-checking and speed up the search.
1475 LinkedConcreteMethodFinder(InstanceKlass* resolved_klass, Method* resolved_method, Method* uniqm = nullptr) : AbstractClassHierarchyWalker(nullptr) {
1476 assert(resolved_klass->is_linked(), "required");
1477 assert(resolved_method->method_holder()->is_linked(), "required");
1478 assert(!resolved_method->can_be_statically_bound(), "no vtable index available");
1479
1480 _resolved_klass = resolved_klass;
1481 _declaring_klass = resolved_method->method_holder();
1482 _vtable_index = compute_vtable_index(resolved_klass, resolved_method,
1483 _do_itable_lookup); // out parameter
1484 assert(_vtable_index >= 0, "invalid vtable index");
1485
1486 initialize(uniqm);
1487 }
1488
1489 // Note: If n==num_participants, returns nullptr.
1490 Method* found_method(uint n) {
1491 assert(n <= num_participants(), "oob");
1492 assert(participant(n) != nullptr || n == num_participants(), "proper usage");
1493 return _found_methods[n];
1494 }
1495 };
1496
1497 Klass* LinkedConcreteMethodFinder::find_witness_in(KlassDepChange& changes) {
1498 Klass* type = changes.type();
1499
1500 assert(!is_participant(type), "only old classes are participants");
1501
1502 if (is_witness(type)) {
1503 return type;
1504 }
1505 return nullptr; // No witness found. The dependency remains unbroken.
1506 }
1507
1508 Klass* LinkedConcreteMethodFinder::find_witness_anywhere(InstanceKlass* context_type) {
1509 for (CountingClassHierarchyIterator iter(context_type); !iter.done(); iter.next()) {
1510 Klass* sub = iter.klass();
1511 if (is_witness(sub)) {
1512 return sub;
1513 }
1514 if (sub->is_instance_klass() && !InstanceKlass::cast(sub)->is_linked()) {
1515 iter.skip_subclasses(); // ignore not yet linked classes
1516 }
1517 }
1518 return nullptr; // No witness found. The dependency remains unbroken.
1519 }
1520
1521 bool LinkedConcreteMethodFinder::is_witness(Klass* k) {
1522 if (is_participant(k)) {
1523 return false; // do not report participant types
1524 } else if (k->is_instance_klass()) {
1525 InstanceKlass* ik = InstanceKlass::cast(k);
1526 if (is_concrete_klass(ik)) {
1527 Method* m = select_method(ik);
1528 return record_witness(ik, m);
1529 } else {
1530 return false; // ignore non-concrete holder class
1531 }
1532 } else {
1533 return false; // no methods to find in an array type
1534 }
1535 }
1536
1537 Method* LinkedConcreteMethodFinder::select_method(InstanceKlass* recv_klass) {
1538 Method* selected_method = nullptr;
1539 if (_do_itable_lookup) {
1540 assert(_declaring_klass->is_interface(), "sanity");
1541 bool implements_interface; // initialized by method_at_itable_or_null()
1542 selected_method = recv_klass->method_at_itable_or_null(_declaring_klass, _vtable_index,
1543 implements_interface); // out parameter
1544 assert(implements_interface, "not implemented");
1545 } else {
1546 selected_method = recv_klass->method_at_vtable(_vtable_index);
1547 }
1548 return selected_method; // nullptr when corresponding slot is empty (AbstractMethodError case)
1549 }
1550
1551 int LinkedConcreteMethodFinder::compute_vtable_index(InstanceKlass* resolved_klass, Method* resolved_method,
1552 // out parameter
1553 bool& is_itable_index) {
1554 if (resolved_klass->is_interface() && resolved_method->has_itable_index()) {
1555 is_itable_index = true;
1556 return resolved_method->itable_index();
1557 }
1558 // Check for default or miranda method first.
1559 InstanceKlass* declaring_klass = resolved_method->method_holder();
1560 if (!resolved_klass->is_interface() && declaring_klass->is_interface()) {
1561 is_itable_index = false;
1562 return resolved_klass->vtable_index_of_interface_method(resolved_method);
1563 }
1564 // At this point we are sure that resolved_method is virtual and not
1565 // a default or miranda method; therefore, it must have a valid vtable index.
1566 assert(resolved_method->has_vtable_index(), "");
1567 is_itable_index = false;
1568 return resolved_method->vtable_index();
1569 }
1570
1571 bool LinkedConcreteMethodFinder::is_concrete_klass(InstanceKlass* ik) {
1572 if (!Dependencies::is_concrete_klass(ik)) {
1573 return false; // not concrete
1574 }
1575 if (ik->is_interface()) {
1576 return false; // interfaces aren't concrete
1577 }
1578 if (!ik->is_linked()) {
1579 return false; // not yet linked classes don't have instances
1580 }
1581 return true;
1582 }
1583
1584 #ifdef ASSERT
1585 // Assert that m is inherited into ctxk, without intervening overrides.
1586 // (May return true even if this is not true, in corner cases where we punt.)
1587 bool Dependencies::verify_method_context(InstanceKlass* ctxk, Method* m) {
1588 if (m->is_private()) {
1589 return false; // Quick lose. Should not happen.
1590 }
1591 if (m->method_holder() == ctxk) {
1592 return true; // Quick win.
1593 }
1594 if (!(m->is_public() || m->is_protected())) {
1595 // The override story is complex when packages get involved.
1596 return true; // Must punt the assertion to true.
1597 }
1598 Method* lm = ctxk->lookup_method(m->name(), m->signature());
1599 if (lm == nullptr) {
1600 // It might be an interface method
1601 lm = ctxk->lookup_method_in_ordered_interfaces(m->name(), m->signature());
1602 }
1603 if (lm == m) {
1604 // Method m is inherited into ctxk.
1605 return true;
1606 }
1607 if (lm != nullptr) {
1608 if (!(lm->is_public() || lm->is_protected())) {
1609 // Method is [package-]private, so the override story is complex.
1610 return true; // Must punt the assertion to true.
1611 }
1612 if (lm->is_static()) {
1613 // Static methods don't override non-static so punt
1614 return true;
1615 }
1616 if (!Dependencies::is_concrete_method(lm, ctxk) &&
1617 !Dependencies::is_concrete_method(m, ctxk)) {
1618 // They are both non-concrete
1619 if (lm->method_holder()->is_subtype_of(m->method_holder())) {
1620 // Method m is overridden by lm, but both are non-concrete.
1621 return true;
1622 }
1623 if (lm->method_holder()->is_interface() && m->method_holder()->is_interface() &&
1624 ctxk->is_subtype_of(m->method_holder()) && ctxk->is_subtype_of(lm->method_holder())) {
1625 // Interface method defined in multiple super interfaces
1626 return true;
1627 }
1628 }
1629 }
1630 ResourceMark rm;
1631 tty->print_cr("Dependency method not found in the associated context:");
1632 tty->print_cr(" context = %s", ctxk->external_name());
1633 tty->print( " method = "); m->print_short_name(tty); tty->cr();
1634 if (lm != nullptr) {
1635 tty->print( " found = "); lm->print_short_name(tty); tty->cr();
1636 }
1637 return false;
1638 }
1639 #endif // ASSERT
1640
1641 bool Dependencies::is_concrete_klass(Klass* k) {
1642 if (k->is_abstract()) return false;
1643 // %%% We could treat classes which are concrete but
1644 // have not yet been instantiated as virtually abstract.
1645 // This would require a deoptimization barrier on first instantiation.
1646 //if (k->is_not_instantiated()) return false;
1647 return true;
1648 }
1649
1650 bool Dependencies::is_concrete_method(Method* m, Klass* k) {
1651 // nullptr is not a concrete method.
1652 if (m == nullptr) {
1653 return false;
1654 }
1655 // Statics are irrelevant to virtual call sites.
1656 if (m->is_static()) {
1657 return false;
1658 }
1659 // Abstract methods are not concrete.
1660 if (m->is_abstract()) {
1661 return false;
1662 }
1663 // Overpass (error) methods are not concrete if k is abstract.
1664 if (m->is_overpass() && k != nullptr) {
1665 return !k->is_abstract();
1666 }
1667 // Note "true" is conservative answer: overpass clause is false if k == nullptr,
1668 // implies return true if answer depends on overpass clause.
1669 return true;
1670 }
1671
1672 Klass* Dependencies::find_finalizable_subclass(InstanceKlass* ik) {
1673 for (ClassHierarchyIterator iter(ik); !iter.done(); iter.next()) {
1674 Klass* sub = iter.klass();
1675 if (sub->has_finalizer() && !sub->is_interface()) {
1676 return sub;
1677 }
1678 }
1679 return nullptr; // not found
1680 }
1681
1682 bool Dependencies::is_concrete_klass(ciInstanceKlass* k) {
1683 if (k->is_abstract()) return false;
1684 // We could also return false if k does not yet appear to be
1685 // instantiated, if the VM version supports this distinction also.
1686 //if (k->is_not_instantiated()) return false;
1687 return true;
1688 }
1689
1690 bool Dependencies::has_finalizable_subclass(ciInstanceKlass* k) {
1691 return k->has_finalizable_subclass();
1692 }
1693
1694 // Any use of the contents (bytecodes) of a method must be
1695 // marked by an "evol_method" dependency, if those contents
1696 // can change. (Note: A method is always dependent on itself.)
1697 Klass* Dependencies::check_evol_method(Method* m) {
1698 assert(must_be_in_vm(), "raw oops here");
1699 // Did somebody do a JVMTI RedefineClasses while our backs were turned?
1700 // Or is there a now a breakpoint?
1701 // (Assumes compiled code cannot handle bkpts; change if UseFastBreakpoints.)
1702 if (m->is_old()
1703 || m->number_of_breakpoints() > 0) {
1704 return m->method_holder();
1705 } else {
1706 return nullptr;
1707 }
1708 }
1709
1710 // This is a strong assertion: It is that the given type
1711 // has no subtypes whatever. It is most useful for
1712 // optimizing checks on reflected types or on array types.
1713 // (Checks on types which are derived from real instances
1714 // can be optimized more strongly than this, because we
1715 // know that the checked type comes from a concrete type,
1716 // and therefore we can disregard abstract types.)
1717 Klass* Dependencies::check_leaf_type(InstanceKlass* ctxk) {
1718 assert(must_be_in_vm(), "raw oops here");
1719 assert_locked_or_safepoint(Compile_lock);
1720 Klass* sub = ctxk->subklass();
1721 if (sub != nullptr) {
1722 return sub;
1723 } else if (ctxk->nof_implementors() != 0) {
1724 // if it is an interface, it must be unimplemented
1725 // (if it is not an interface, nof_implementors is always zero)
1726 InstanceKlass* impl = ctxk->implementor();
1727 assert(impl != nullptr, "must be set");
1728 return impl;
1729 } else {
1730 return nullptr;
1731 }
1732 }
1733
1734 // Test the assertion that conck is the only concrete subtype* of ctxk.
1735 // The type conck itself is allowed to have have further concrete subtypes.
1736 // This allows the compiler to narrow occurrences of ctxk by conck,
1737 // when dealing with the types of actual instances.
1738 Klass* Dependencies::check_abstract_with_unique_concrete_subtype(InstanceKlass* ctxk,
1739 Klass* conck,
1740 NewKlassDepChange* changes) {
1741 ConcreteSubtypeFinder wf(conck);
1742 Klass* k = wf.find_witness(ctxk, changes);
1743 return k;
1744 }
1745
1746
1747 // Find the unique concrete proper subtype of ctxk, or nullptr if there
1748 // is more than one concrete proper subtype. If there are no concrete
1749 // proper subtypes, return ctxk itself, whether it is concrete or not.
1750 // The returned subtype is allowed to have have further concrete subtypes.
1751 // That is, return CC1 for CX > CC1 > CC2, but nullptr for CX > { CC1, CC2 }.
1752 Klass* Dependencies::find_unique_concrete_subtype(InstanceKlass* ctxk) {
1753 ConcreteSubtypeFinder wf(ctxk); // Ignore ctxk when walking.
1754 wf.record_witnesses(1); // Record one other witness when walking.
1755 Klass* wit = wf.find_witness(ctxk);
1756 if (wit != nullptr) return nullptr; // Too many witnesses.
1757 Klass* conck = wf.participant(0);
1758 if (conck == nullptr) {
1759 return ctxk; // Return ctxk as a flag for "no subtypes".
1760 } else {
1761 #ifndef PRODUCT
1762 // Make sure the dependency mechanism will pass this discovery:
1763 if (VerifyDependencies) {
1764 // Turn off dependency tracing while actually testing deps.
1765 FlagSetting fs(_verify_in_progress, true);
1766 if (!Dependencies::is_concrete_klass(ctxk)) {
1767 guarantee(nullptr == (void *)
1768 check_abstract_with_unique_concrete_subtype(ctxk, conck),
1769 "verify dep.");
1770 }
1771 }
1772 #endif //PRODUCT
1773 return conck;
1774 }
1775 }
1776
1777 // Try to determine whether root method in some context is concrete or not based on the information about the unique method
1778 // in that context. It exploits the fact that concrete root method is always inherited into the context when there's a unique method.
1779 // Hence, unique method holder is always a supertype of the context class when root method is concrete.
1780 // Examples for concrete_root_method
1781 // C (C.m uniqm)
1782 // |
1783 // CX (ctxk) uniqm is inherited into context.
1784 //
1785 // CX (ctxk) (CX.m uniqm) here uniqm is defined in ctxk.
1786 // Examples for !concrete_root_method
1787 // CX (ctxk)
1788 // |
1789 // C (C.m uniqm) uniqm is in subtype of ctxk.
1790 bool Dependencies::is_concrete_root_method(Method* uniqm, InstanceKlass* ctxk) {
1791 if (uniqm == nullptr) {
1792 return false; // match Dependencies::is_concrete_method() behavior
1793 }
1794 // Theoretically, the "direction" of subtype check matters here.
1795 // On one hand, in case of interface context with a single implementor, uniqm can be in a superclass of the implementor which
1796 // is not related to context class.
1797 // On another hand, uniqm could come from an interface unrelated to the context class, but right now it is not possible:
1798 // it is required that uniqm->method_holder() is the participant (uniqm->method_holder() <: ctxk), hence a default method
1799 // can't be used as unique.
1800 if (ctxk->is_interface()) {
1801 InstanceKlass* implementor = ctxk->implementor();
1802 assert(implementor != ctxk, "single implementor only"); // should have been invalidated earlier
1803 ctxk = implementor;
1804 }
1805 InstanceKlass* holder = uniqm->method_holder();
1806 assert(!holder->is_interface(), "no default methods allowed");
1807 assert(ctxk->is_subclass_of(holder) || holder->is_subclass_of(ctxk), "not related");
1808 return ctxk->is_subclass_of(holder);
1809 }
1810
1811 // If a class (or interface) has a unique concrete method uniqm, return nullptr.
1812 // Otherwise, return a class that contains an interfering method.
1813 Klass* Dependencies::check_unique_concrete_method(InstanceKlass* ctxk,
1814 Method* uniqm,
1815 NewKlassDepChange* changes) {
1816 ConcreteMethodFinder wf(uniqm, uniqm->method_holder());
1817 Klass* k = wf.find_witness(ctxk, changes);
1818 if (k != nullptr) {
1819 return k;
1820 }
1821 if (!Dependencies::is_concrete_root_method(uniqm, ctxk) || changes != nullptr) {
1822 Klass* conck = find_witness_AME(ctxk, uniqm, changes);
1823 if (conck != nullptr) {
1824 // Found a concrete subtype 'conck' which does not override abstract root method.
1825 return conck;
1826 }
1827 }
1828 return nullptr;
1829 }
1830
1831 Klass* Dependencies::check_unique_implementor(InstanceKlass* ctxk, Klass* uniqk, NewKlassDepChange* changes) {
1832 assert(ctxk->is_interface(), "sanity");
1833 assert(ctxk->nof_implementors() > 0, "no implementors");
1834 if (ctxk->nof_implementors() == 1) {
1835 assert(ctxk->implementor() == uniqk, "sanity");
1836 return nullptr;
1837 }
1838 return ctxk; // no unique implementor
1839 }
1840
1841 // Search for AME.
1842 // There are two version of checks.
1843 // 1) Spot checking version(Classload time). Newly added class is checked for AME.
1844 // Checks whether abstract/overpass method is inherited into/declared in newly added concrete class.
1845 // 2) Compile time analysis for abstract/overpass(abstract klass) root_m. The non uniqm subtrees are checked for concrete classes.
1846 Klass* Dependencies::find_witness_AME(InstanceKlass* ctxk, Method* m, KlassDepChange* changes) {
1847 if (m != nullptr) {
1848 if (changes != nullptr) {
1849 // Spot checking version.
1850 ConcreteMethodFinder wf(m);
1851 Klass* new_type = changes->as_new_klass_change()->new_type();
1852 if (wf.witnessed_reabstraction_in_supers(new_type)) {
1853 return new_type;
1854 }
1855 } else {
1856 // Note: It is required that uniqm->method_holder() is the participant (see ClassHierarchyWalker::found_method()).
1857 ConcreteSubtypeFinder wf(m->method_holder());
1858 Klass* conck = wf.find_witness(ctxk);
1859 if (conck != nullptr) {
1860 Method* cm = InstanceKlass::cast(conck)->find_instance_method(m->name(), m->signature(), Klass::PrivateLookupMode::skip);
1861 if (!Dependencies::is_concrete_method(cm, conck)) {
1862 return conck;
1863 }
1864 }
1865 }
1866 }
1867 return nullptr;
1868 }
1869
1870 // This function is used by find_unique_concrete_method(non vtable based)
1871 // to check whether subtype method overrides the base method.
1872 static bool overrides(Method* sub_m, Method* base_m) {
1873 assert(base_m != nullptr, "base method should be non null");
1874 if (sub_m == nullptr) {
1875 return false;
1876 }
1877 /**
1878 * If base_m is public or protected then sub_m always overrides.
1879 * If base_m is !public, !protected and !private (i.e. base_m is package private)
1880 * then sub_m should be in the same package as that of base_m.
1881 * For package private base_m this is conservative approach as it allows only subset of all allowed cases in
1882 * the jvm specification.
1883 **/
1884 if (base_m->is_public() || base_m->is_protected() ||
1885 base_m->method_holder()->is_same_class_package(sub_m->method_holder())) {
1886 return true;
1887 }
1888 return false;
1889 }
1890
1891 // Find the set of all non-abstract methods under ctxk that match m.
1892 // (The method m must be defined or inherited in ctxk.)
1893 // Include m itself in the set, unless it is abstract.
1894 // If this set has exactly one element, return that element.
1895 Method* Dependencies::find_unique_concrete_method(InstanceKlass* ctxk, Method* m, Klass** participant) {
1896 // Return nullptr if m is marked old; must have been a redefined method.
1897 if (m->is_old()) {
1898 return nullptr;
1899 }
1900 if (m->is_default_method()) {
1901 return nullptr; // not supported
1902 }
1903 assert(verify_method_context(ctxk, m), "proper context");
1904 ConcreteMethodFinder wf(m);
1905 wf.record_witnesses(1);
1906 Klass* wit = wf.find_witness(ctxk);
1907 if (wit != nullptr) return nullptr; // Too many witnesses.
1908 Method* fm = wf.found_method(0); // Will be nullptr if num_parts == 0.
1909 if (participant != nullptr) {
1910 (*participant) = wf.participant(0);
1911 }
1912 if (!Dependencies::is_concrete_method(fm, nullptr)) {
1913 fm = nullptr; // ignore abstract methods
1914 }
1915 if (Dependencies::is_concrete_method(m, ctxk)) {
1916 if (fm == nullptr) {
1917 // It turns out that m was always the only implementation.
1918 fm = m;
1919 } else if (fm != m) {
1920 // Two conflicting implementations after all.
1921 // (This can happen if m is inherited into ctxk and fm overrides it.)
1922 return nullptr;
1923 }
1924 } else if (Dependencies::find_witness_AME(ctxk, fm) != nullptr) {
1925 // Found a concrete subtype which does not override abstract root method.
1926 return nullptr;
1927 } else if (!overrides(fm, m)) {
1928 // Found method doesn't override abstract root method.
1929 return nullptr;
1930 }
1931 assert(Dependencies::is_concrete_root_method(fm, ctxk) == Dependencies::is_concrete_method(m, ctxk), "mismatch");
1932 #ifndef PRODUCT
1933 // Make sure the dependency mechanism will pass this discovery:
1934 if (VerifyDependencies && fm != nullptr) {
1935 guarantee(nullptr == (void *)check_unique_concrete_method(ctxk, fm),
1936 "verify dep.");
1937 }
1938 #endif //PRODUCT
1939 return fm;
1940 }
1941
1942 // If a class (or interface) has a unique concrete method uniqm, return nullptr.
1943 // Otherwise, return a class that contains an interfering method.
1944 Klass* Dependencies::check_unique_concrete_method(InstanceKlass* ctxk,
1945 Method* uniqm,
1946 Klass* resolved_klass,
1947 Method* resolved_method,
1948 KlassDepChange* changes) {
1949 assert(!ctxk->is_interface() || ctxk == resolved_klass, "sanity");
1950 assert(!resolved_method->can_be_statically_bound() || resolved_method == uniqm, "sanity");
1951 assert(resolved_klass->is_subtype_of(resolved_method->method_holder()), "sanity");
1952
1953 if (!InstanceKlass::cast(resolved_klass)->is_linked() ||
1954 !resolved_method->method_holder()->is_linked() ||
1955 resolved_method->can_be_statically_bound()) {
1956 // Dependency is redundant, but benign. Just keep it to avoid unnecessary recompilation.
1957 return nullptr; // no vtable index available
1958 }
1959
1960 LinkedConcreteMethodFinder mf(InstanceKlass::cast(resolved_klass), resolved_method, uniqm);
1961 return mf.find_witness(ctxk, changes);
1962 }
1963
1964 // Find the set of all non-abstract methods under ctxk that match m.
1965 // (The method m must be defined or inherited in ctxk.)
1966 // Include m itself in the set, unless it is abstract.
1967 // If this set has exactly one element, return that element.
1968 // Not yet linked subclasses of ctxk are ignored since they don't have any instances yet.
1969 // Additionally, resolved_klass and resolved_method complete the description of the call site being analyzed.
1970 Method* Dependencies::find_unique_concrete_method(InstanceKlass* ctxk, Method* m, Klass* resolved_klass, Method* resolved_method) {
1971 // Return nullptr if m is marked old; must have been a redefined method.
1972 if (m->is_old()) {
1973 return nullptr;
1974 }
1975 if (!InstanceKlass::cast(resolved_klass)->is_linked() ||
1976 !resolved_method->method_holder()->is_linked() ||
1977 resolved_method->can_be_statically_bound()) {
1978 return m; // nothing to do: no witness under ctxk
1979 }
1980 LinkedConcreteMethodFinder wf(InstanceKlass::cast(resolved_klass), resolved_method);
1981 assert(Dependencies::verify_method_context(ctxk, m), "proper context");
1982 wf.record_witnesses(1);
1983 Klass* wit = wf.find_witness(ctxk);
1984 if (wit != nullptr) {
1985 return nullptr; // Too many witnesses.
1986 }
1987 // p == nullptr when no participants are found (wf.num_participants() == 0).
1988 // fm == nullptr case has 2 meanings:
1989 // * when p == nullptr: no method found;
1990 // * when p != nullptr: AbstractMethodError-throwing method found.
1991 // Also, found method should always be accompanied by a participant class.
1992 Klass* p = wf.participant(0);
1993 Method* fm = wf.found_method(0);
1994 assert(fm == nullptr || p != nullptr, "no participant");
1995 // Normalize all error-throwing cases to nullptr.
1996 if (fm == Universe::throw_illegal_access_error() ||
1997 fm == Universe::throw_no_such_method_error() ||
1998 !Dependencies::is_concrete_method(fm, p)) {
1999 fm = nullptr; // error-throwing method
2000 }
2001 if (Dependencies::is_concrete_method(m, ctxk)) {
2002 if (p == nullptr) {
2003 // It turns out that m was always the only implementation.
2004 assert(fm == nullptr, "sanity");
2005 fm = m;
2006 }
2007 }
2008 #ifndef PRODUCT
2009 // Make sure the dependency mechanism will pass this discovery:
2010 if (VerifyDependencies && fm != nullptr) {
2011 guarantee(nullptr == check_unique_concrete_method(ctxk, fm, resolved_klass, resolved_method),
2012 "verify dep.");
2013 }
2014 #endif // PRODUCT
2015 assert(fm == nullptr || !fm->is_abstract(), "sanity");
2016 // Old CHA conservatively reports concrete methods in abstract classes
2017 // irrespective of whether they have concrete subclasses or not.
2018 // Also, abstract root method case is not fully supported.
2019 #ifdef ASSERT
2020 Klass* uniqp = nullptr;
2021 Method* uniqm = Dependencies::find_unique_concrete_method(ctxk, m, &uniqp);
2022 assert(uniqm == nullptr || uniqm == fm ||
2023 m->is_abstract() ||
2024 uniqm->method_holder()->is_abstract() ||
2025 (fm == nullptr && uniqm != nullptr && uniqp != nullptr && !InstanceKlass::cast(uniqp)->is_linked()),
2026 "sanity");
2027 #endif // ASSERT
2028 return fm;
2029 }
2030
2031 Klass* Dependencies::check_has_no_finalizable_subclasses(InstanceKlass* ctxk, NewKlassDepChange* changes) {
2032 InstanceKlass* search_at = ctxk;
2033 if (changes != nullptr) {
2034 search_at = changes->new_type(); // just look at the new bit
2035 }
2036 return find_finalizable_subclass(search_at);
2037 }
2038
2039 Klass* Dependencies::check_call_site_target_value(oop call_site, oop method_handle, CallSiteDepChange* changes) {
2040 assert(call_site != nullptr, "sanity");
2041 assert(method_handle != nullptr, "sanity");
2042 assert(call_site->is_a(vmClasses::CallSite_klass()), "sanity");
2043
2044 if (changes == nullptr) {
2045 // Validate all CallSites
2046 if (java_lang_invoke_CallSite::target(call_site) != method_handle)
2047 return call_site->klass(); // assertion failed
2048 } else {
2049 // Validate the given CallSite
2050 if (call_site == changes->call_site() && java_lang_invoke_CallSite::target(call_site) != changes->method_handle()) {
2051 assert(method_handle != changes->method_handle(), "must be");
2052 return call_site->klass(); // assertion failed
2053 }
2054 }
2055 return nullptr; // assertion still valid
2056 }
2057
2058 void Dependencies::DepStream::trace_and_log_witness(Klass* witness) {
2059 if (_verify_in_progress) return; // don't log
2060 if (witness != nullptr) {
2061 LogTarget(Debug, dependencies) lt;
2062 if (lt.is_enabled()) {
2063 LogStream ls(<);
2064 print_dependency(&ls, witness, /*verbose=*/ true);
2065 }
2066 // The following is a no-op unless logging is enabled:
2067 log_dependency(witness);
2068 }
2069 }
2070
2071 Klass* Dependencies::DepStream::check_new_klass_dependency(NewKlassDepChange* changes) {
2072 assert_locked_or_safepoint(Compile_lock);
2073 Dependencies::check_valid_dependency_type(type());
2074
2075 Klass* witness = nullptr;
2076 switch (type()) {
2077 case evol_method:
2078 witness = check_evol_method(method_argument(0));
2079 break;
2080 case leaf_type:
2081 witness = check_leaf_type(context_type());
2082 break;
2083 case abstract_with_unique_concrete_subtype:
2084 witness = check_abstract_with_unique_concrete_subtype(context_type(), type_argument(1), changes);
2085 break;
2086 case unique_concrete_method_2:
2087 witness = check_unique_concrete_method(context_type(), method_argument(1), changes);
2088 break;
2089 case unique_concrete_method_4:
2090 witness = check_unique_concrete_method(context_type(), method_argument(1), type_argument(2), method_argument(3), changes);
2091 break;
2092 case unique_implementor:
2093 witness = check_unique_implementor(context_type(), type_argument(1), changes);
2094 break;
2095 case no_finalizable_subclasses:
2096 witness = check_has_no_finalizable_subclasses(context_type(), changes);
2097 break;
2098 default:
2099 witness = nullptr;
2100 break;
2101 }
2102 trace_and_log_witness(witness);
2103 return witness;
2104 }
2105
2106 Klass* Dependencies::DepStream::check_klass_init_dependency(KlassInitDepChange* changes) {
2107 assert_locked_or_safepoint(Compile_lock);
2108 Dependencies::check_valid_dependency_type(type());
2109
2110 // No new types added. Only unique_concrete_method_4 is sensitive to class initialization changes.
2111 Klass* witness = nullptr;
2112 switch (type()) {
2113 case unique_concrete_method_4:
2114 witness = check_unique_concrete_method(context_type(), method_argument(1), type_argument(2), method_argument(3), changes);
2115 break;
2116 default:
2117 witness = nullptr;
2118 break;
2119 }
2120 trace_and_log_witness(witness);
2121 return witness;
2122 }
2123
2124 Klass* Dependencies::DepStream::check_klass_dependency(KlassDepChange* changes) {
2125 assert_locked_or_safepoint(Compile_lock);
2126 Dependencies::check_valid_dependency_type(type());
2127
2128 if (changes != nullptr) {
2129 if (changes->is_klass_init_change()) {
2130 return check_klass_init_dependency(changes->as_klass_init_change());
2131 } else {
2132 return check_new_klass_dependency(changes->as_new_klass_change());
2133 }
2134 } else {
2135 Klass* witness = check_new_klass_dependency(nullptr);
2136 // check_klass_init_dependency duplicates check_new_klass_dependency checks when class hierarchy change info is absent.
2137 assert(witness != nullptr || check_klass_init_dependency(nullptr) == nullptr, "missed dependency");
2138 return witness;
2139 }
2140 }
2141
2142 Klass* Dependencies::DepStream::check_call_site_dependency(CallSiteDepChange* changes) {
2143 assert_locked_or_safepoint(Compile_lock);
2144 Dependencies::check_valid_dependency_type(type());
2145
2146 Klass* witness = nullptr;
2147 switch (type()) {
2148 case call_site_target_value:
2149 witness = check_call_site_target_value(argument_oop(0), argument_oop(1), changes);
2150 break;
2151 default:
2152 witness = nullptr;
2153 break;
2154 }
2155 trace_and_log_witness(witness);
2156 return witness;
2157 }
2158
2159
2160 Klass* Dependencies::DepStream::spot_check_dependency_at(DepChange& changes) {
2161 // Handle klass dependency
2162 if (changes.is_klass_change() && changes.as_klass_change()->involves_context(context_type()))
2163 return check_klass_dependency(changes.as_klass_change());
2164
2165 // Handle CallSite dependency
2166 if (changes.is_call_site_change())
2167 return check_call_site_dependency(changes.as_call_site_change());
2168
2169 // irrelevant dependency; skip it
2170 return nullptr;
2171 }
2172
2173
2174 void DepChange::print() { print_on(tty); }
2175
2176 void DepChange::print_on(outputStream* st) {
2177 int nsup = 0, nint = 0;
2178 for (ContextStream str(*this); str.next(); ) {
2179 InstanceKlass* k = str.klass();
2180 switch (str.change_type()) {
2181 case Change_new_type:
2182 st->print_cr(" dependee = %s", k->external_name());
2183 break;
2184 case Change_new_sub:
2185 if (!WizardMode) {
2186 ++nsup;
2187 } else {
2188 st->print_cr(" context super = %s", k->external_name());
2189 }
2190 break;
2191 case Change_new_impl:
2192 if (!WizardMode) {
2193 ++nint;
2194 } else {
2195 st->print_cr(" context interface = %s", k->external_name());
2196 }
2197 break;
2198 default:
2199 break;
2200 }
2201 }
2202 if (nsup + nint != 0) {
2203 st->print_cr(" context supers = %d, interfaces = %d", nsup, nint);
2204 }
2205 }
2206
2207 void DepChange::ContextStream::start() {
2208 InstanceKlass* type = (_changes.is_klass_change() ? _changes.as_klass_change()->type() : (InstanceKlass*) nullptr);
2209 _change_type = (type == nullptr ? NO_CHANGE : Start_Klass);
2210 _klass = type;
2211 _ti_base = nullptr;
2212 _ti_index = 0;
2213 _ti_limit = 0;
2214 }
2215
2216 bool DepChange::ContextStream::next() {
2217 switch (_change_type) {
2218 case Start_Klass: // initial state; _klass is the new type
2219 _ti_base = _klass->transitive_interfaces();
2220 _ti_index = 0;
2221 _change_type = Change_new_type;
2222 return true;
2223 case Change_new_type:
2224 // fall through:
2225 _change_type = Change_new_sub;
2226 case Change_new_sub:
2227 // 6598190: brackets workaround Sun Studio C++ compiler bug 6629277
2228 {
2229 _klass = _klass->java_super();
2230 if (_klass != nullptr) {
2231 return true;
2232 }
2233 }
2234 // else set up _ti_limit and fall through:
2235 _ti_limit = (_ti_base == nullptr) ? 0 : _ti_base->length();
2236 _change_type = Change_new_impl;
2237 case Change_new_impl:
2238 if (_ti_index < _ti_limit) {
2239 _klass = _ti_base->at(_ti_index++);
2240 return true;
2241 }
2242 // fall through:
2243 _change_type = NO_CHANGE; // iterator is exhausted
2244 case NO_CHANGE:
2245 break;
2246 default:
2247 ShouldNotReachHere();
2248 }
2249 return false;
2250 }
2251
2252 void KlassDepChange::initialize() {
2253 // entire transaction must be under this lock:
2254 assert_lock_strong(Compile_lock);
2255
2256 // Mark all dependee and all its superclasses
2257 // Mark transitive interfaces
2258 for (ContextStream str(*this); str.next(); ) {
2259 InstanceKlass* d = str.klass();
2260 assert(!d->is_marked_dependent(), "checking");
2261 d->set_is_marked_dependent(true);
2262 }
2263 }
2264
2265 KlassDepChange::~KlassDepChange() {
2266 // Unmark all dependee and all its superclasses
2267 // Unmark transitive interfaces
2268 for (ContextStream str(*this); str.next(); ) {
2269 InstanceKlass* d = str.klass();
2270 d->set_is_marked_dependent(false);
2271 }
2272 }
2273
2274 bool KlassDepChange::involves_context(Klass* k) {
2275 if (k == nullptr || !k->is_instance_klass()) {
2276 return false;
2277 }
2278 InstanceKlass* ik = InstanceKlass::cast(k);
2279 bool is_contained = ik->is_marked_dependent();
2280 assert(is_contained == type()->is_subtype_of(k),
2281 "correct marking of potential context types");
2282 return is_contained;
2283 }
2284
2285 void Dependencies::print_statistics() {
2286 AbstractClassHierarchyWalker::print_statistics();
2287 }
2288
2289 void AbstractClassHierarchyWalker::print_statistics() {
2290 if (UsePerfData) {
2291 jlong deps_find_witness_calls = _perf_find_witness_anywhere_calls_count->get_value();
2292 jlong deps_find_witness_steps = _perf_find_witness_anywhere_steps_count->get_value();
2293 jlong deps_find_witness_singles = _perf_find_witness_in_calls_count->get_value();
2294
2295 ttyLocker ttyl;
2296 tty->print_cr("Dependency check (find_witness) "
2297 "calls=" JLONG_FORMAT ", steps=" JLONG_FORMAT " (avg=%.1f), singles=" JLONG_FORMAT,
2298 deps_find_witness_calls,
2299 deps_find_witness_steps,
2300 (double)deps_find_witness_steps / deps_find_witness_calls,
2301 deps_find_witness_singles);
2302 if (xtty != nullptr) {
2303 xtty->elem("deps_find_witness calls='" JLONG_FORMAT "' steps='" JLONG_FORMAT "' singles='" JLONG_FORMAT "'",
2304 deps_find_witness_calls,
2305 deps_find_witness_steps,
2306 deps_find_witness_singles);
2307 }
2308 }
2309 }
2310
2311 CallSiteDepChange::CallSiteDepChange(Handle call_site, Handle method_handle) :
2312 _call_site(call_site),
2313 _method_handle(method_handle) {
2314 assert(_call_site()->is_a(vmClasses::CallSite_klass()), "must be");
2315 assert(_method_handle.is_null() || _method_handle()->is_a(vmClasses::MethodHandle_klass()), "must be");
2316 }
2317
2318 void dependencies_init() {
2319 AbstractClassHierarchyWalker::init();
2320 }