1 /*
2 * Copyright (c) 2005, 2023, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "ci/ciArrayKlass.hpp"
27 #include "ci/ciEnv.hpp"
28 #include "ci/ciKlass.hpp"
29 #include "ci/ciMethod.hpp"
30 #include "classfile/javaClasses.inline.hpp"
31 #include "classfile/vmClasses.hpp"
32 #include "code/dependencies.hpp"
33 #include "compiler/compileLog.hpp"
34 #include "compiler/compileBroker.hpp"
35 #include "compiler/compileTask.hpp"
36 #include "memory/resourceArea.hpp"
37 #include "oops/klass.hpp"
38 #include "oops/oop.inline.hpp"
39 #include "oops/method.inline.hpp"
40 #include "oops/objArrayKlass.hpp"
41 #include "runtime/flags/flagSetting.hpp"
42 #include "runtime/handles.hpp"
43 #include "runtime/handles.inline.hpp"
44 #include "runtime/javaThread.inline.hpp"
45 #include "runtime/jniHandles.inline.hpp"
46 #include "runtime/mutexLocker.hpp"
47 #include "runtime/perfData.hpp"
48 #include "runtime/vmThread.hpp"
49 #include "utilities/copy.hpp"
50
51
52 #ifdef ASSERT
53 static bool must_be_in_vm() {
54 Thread* thread = Thread::current();
55 if (thread->is_Java_thread()) {
56 return JavaThread::cast(thread)->thread_state() == _thread_in_vm;
57 } else {
58 return true; // Could be VMThread or GC thread
59 }
60 }
61 #endif //ASSERT
62
63 bool Dependencies::_verify_in_progress = false; // don't -Xlog:dependencies
64
65 void Dependencies::initialize(ciEnv* env) {
66 Arena* arena = env->arena();
67 _oop_recorder = env->oop_recorder();
68 _log = env->log();
69 _dep_seen = new(arena) GrowableArray<int>(arena, 500, 0, 0);
70 #if INCLUDE_JVMCI
71 _using_dep_values = false;
72 #endif
73 DEBUG_ONLY(_deps[end_marker] = nullptr);
74 for (int i = (int)FIRST_TYPE; i < (int)TYPE_LIMIT; i++) {
75 _deps[i] = new(arena) GrowableArray<ciBaseObject*>(arena, 10, 0, 0);
76 }
77 _content_bytes = nullptr;
78 _size_in_bytes = (size_t)-1;
79
80 assert(TYPE_LIMIT <= (1<<LG2_TYPE_LIMIT), "sanity");
81 }
82
83 void Dependencies::assert_evol_method(ciMethod* m) {
84 assert_common_1(evol_method, m);
85 }
86
87 void Dependencies::assert_leaf_type(ciKlass* ctxk) {
88 if (ctxk->is_array_klass()) {
89 // As a special case, support this assertion on an array type,
90 // which reduces to an assertion on its element type.
91 // Note that this cannot be done with assertions that
92 // relate to concreteness or abstractness.
93 ciType* elemt = ctxk->as_array_klass()->base_element_type();
94 if (!elemt->is_instance_klass()) return; // Ex: int[][]
95 ctxk = elemt->as_instance_klass();
96 //if (ctxk->is_final()) return; // Ex: String[][]
97 }
98 check_ctxk(ctxk);
99 assert_common_1(leaf_type, ctxk);
100 }
101
102 void Dependencies::assert_abstract_with_unique_concrete_subtype(ciKlass* ctxk, ciKlass* conck) {
103 check_ctxk_abstract(ctxk);
104 assert_common_2(abstract_with_unique_concrete_subtype, ctxk, conck);
105 }
106
107 void Dependencies::assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm) {
108 check_ctxk(ctxk);
109 check_unique_method(ctxk, uniqm);
110 assert_common_2(unique_concrete_method_2, ctxk, uniqm);
111 }
112
113 void Dependencies::assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm, ciKlass* resolved_klass, ciMethod* resolved_method) {
114 check_ctxk(ctxk);
115 check_unique_method(ctxk, uniqm);
116 if (UseVtableBasedCHA) {
117 assert_common_4(unique_concrete_method_4, ctxk, uniqm, resolved_klass, resolved_method);
118 } else {
119 assert_common_2(unique_concrete_method_2, ctxk, uniqm);
120 }
121 }
122
123 void Dependencies::assert_unique_implementor(ciInstanceKlass* ctxk, ciInstanceKlass* uniqk) {
124 check_ctxk(ctxk);
125 check_unique_implementor(ctxk, uniqk);
126 assert_common_2(unique_implementor, ctxk, uniqk);
127 }
128
129 void Dependencies::assert_has_no_finalizable_subclasses(ciKlass* ctxk) {
130 check_ctxk(ctxk);
131 assert_common_1(no_finalizable_subclasses, ctxk);
132 }
133
134 void Dependencies::assert_call_site_target_value(ciCallSite* call_site, ciMethodHandle* method_handle) {
135 assert_common_2(call_site_target_value, call_site, method_handle);
136 }
137
138 #if INCLUDE_JVMCI
139
140 Dependencies::Dependencies(Arena* arena, OopRecorder* oop_recorder, CompileLog* log) {
141 _oop_recorder = oop_recorder;
142 _log = log;
143 _dep_seen = new(arena) GrowableArray<int>(arena, 500, 0, 0);
144 _using_dep_values = true;
145 DEBUG_ONLY(_dep_values[end_marker] = nullptr);
146 for (int i = (int)FIRST_TYPE; i < (int)TYPE_LIMIT; i++) {
147 _dep_values[i] = new(arena) GrowableArray<DepValue>(arena, 10, 0, DepValue());
148 }
149 _content_bytes = nullptr;
150 _size_in_bytes = (size_t)-1;
151
152 assert(TYPE_LIMIT <= (1<<LG2_TYPE_LIMIT), "sanity");
153 }
154
155 void Dependencies::assert_evol_method(Method* m) {
156 assert_common_1(evol_method, DepValue(_oop_recorder, m));
157 }
158
159 void Dependencies::assert_has_no_finalizable_subclasses(Klass* ctxk) {
160 check_ctxk(ctxk);
161 assert_common_1(no_finalizable_subclasses, DepValue(_oop_recorder, ctxk));
162 }
163
164 void Dependencies::assert_leaf_type(Klass* ctxk) {
165 if (ctxk->is_array_klass()) {
166 // As a special case, support this assertion on an array type,
167 // which reduces to an assertion on its element type.
168 // Note that this cannot be done with assertions that
169 // relate to concreteness or abstractness.
170 BasicType elemt = ArrayKlass::cast(ctxk)->element_type();
171 if (is_java_primitive(elemt)) return; // Ex: int[][]
172 ctxk = ObjArrayKlass::cast(ctxk)->bottom_klass();
173 //if (ctxk->is_final()) return; // Ex: String[][]
174 }
175 check_ctxk(ctxk);
176 assert_common_1(leaf_type, DepValue(_oop_recorder, ctxk));
177 }
178
179 void Dependencies::assert_abstract_with_unique_concrete_subtype(Klass* ctxk, Klass* conck) {
180 check_ctxk_abstract(ctxk);
181 DepValue ctxk_dv(_oop_recorder, ctxk);
182 DepValue conck_dv(_oop_recorder, conck, &ctxk_dv);
183 assert_common_2(abstract_with_unique_concrete_subtype, ctxk_dv, conck_dv);
184 }
185
186 void Dependencies::assert_unique_implementor(InstanceKlass* ctxk, InstanceKlass* uniqk) {
187 check_ctxk(ctxk);
188 assert(ctxk->is_interface(), "not an interface");
189 assert(ctxk->implementor() == uniqk, "not a unique implementor");
190 assert_common_2(unique_implementor, DepValue(_oop_recorder, ctxk), DepValue(_oop_recorder, uniqk));
191 }
192
193 void Dependencies::assert_unique_concrete_method(Klass* ctxk, Method* uniqm) {
194 check_ctxk(ctxk);
195 check_unique_method(ctxk, uniqm);
196 assert_common_2(unique_concrete_method_2, DepValue(_oop_recorder, ctxk), DepValue(_oop_recorder, uniqm));
197 }
198
199 void Dependencies::assert_call_site_target_value(oop call_site, oop method_handle) {
200 assert_common_2(call_site_target_value, DepValue(_oop_recorder, JNIHandles::make_local(call_site)), DepValue(_oop_recorder, JNIHandles::make_local(method_handle)));
201 }
202
203 #endif // INCLUDE_JVMCI
204
205
206 // Helper function. If we are adding a new dep. under ctxk2,
207 // try to find an old dep. under a broader* ctxk1. If there is
208 //
209 bool Dependencies::maybe_merge_ctxk(GrowableArray<ciBaseObject*>* deps,
210 int ctxk_i, ciKlass* ctxk2) {
211 ciKlass* ctxk1 = deps->at(ctxk_i)->as_metadata()->as_klass();
212 if (ctxk2->is_subtype_of(ctxk1)) {
213 return true; // success, and no need to change
214 } else if (ctxk1->is_subtype_of(ctxk2)) {
215 // new context class fully subsumes previous one
216 deps->at_put(ctxk_i, ctxk2);
217 return true;
218 } else {
219 return false;
220 }
221 }
222
223 void Dependencies::assert_common_1(DepType dept, ciBaseObject* x) {
224 assert(dep_args(dept) == 1, "sanity");
225 log_dependency(dept, x);
226 GrowableArray<ciBaseObject*>* deps = _deps[dept];
227
228 // see if the same (or a similar) dep is already recorded
229 if (note_dep_seen(dept, x)) {
230 assert(deps->find(x) >= 0, "sanity");
231 } else {
232 deps->append(x);
233 }
234 }
235
236 void Dependencies::assert_common_2(DepType dept,
237 ciBaseObject* x0, ciBaseObject* x1) {
238 assert(dep_args(dept) == 2, "sanity");
239 log_dependency(dept, x0, x1);
240 GrowableArray<ciBaseObject*>* deps = _deps[dept];
241
242 // see if the same (or a similar) dep is already recorded
243 bool has_ctxk = has_explicit_context_arg(dept);
244 if (has_ctxk) {
245 assert(dep_context_arg(dept) == 0, "sanity");
246 if (note_dep_seen(dept, x1)) {
247 // look in this bucket for redundant assertions
248 const int stride = 2;
249 for (int i = deps->length(); (i -= stride) >= 0; ) {
250 ciBaseObject* y1 = deps->at(i+1);
251 if (x1 == y1) { // same subject; check the context
252 if (maybe_merge_ctxk(deps, i+0, x0->as_metadata()->as_klass())) {
253 return;
254 }
255 }
256 }
257 }
258 } else {
259 bool dep_seen_x0 = note_dep_seen(dept, x0); // records x0 for future queries
260 bool dep_seen_x1 = note_dep_seen(dept, x1); // records x1 for future queries
261 if (dep_seen_x0 && dep_seen_x1) {
262 // look in this bucket for redundant assertions
263 const int stride = 2;
264 for (int i = deps->length(); (i -= stride) >= 0; ) {
265 ciBaseObject* y0 = deps->at(i+0);
266 ciBaseObject* y1 = deps->at(i+1);
267 if (x0 == y0 && x1 == y1) {
268 return;
269 }
270 }
271 }
272 }
273
274 // append the assertion in the correct bucket:
275 deps->append(x0);
276 deps->append(x1);
277 }
278
279 void Dependencies::assert_common_4(DepType dept,
280 ciKlass* ctxk, ciBaseObject* x1, ciBaseObject* x2, ciBaseObject* x3) {
281 assert(has_explicit_context_arg(dept), "sanity");
282 assert(dep_context_arg(dept) == 0, "sanity");
283 assert(dep_args(dept) == 4, "sanity");
284 log_dependency(dept, ctxk, x1, x2, x3);
285 GrowableArray<ciBaseObject*>* deps = _deps[dept];
286
287 // see if the same (or a similar) dep is already recorded
288 bool dep_seen_x1 = note_dep_seen(dept, x1); // records x1 for future queries
289 bool dep_seen_x2 = note_dep_seen(dept, x2); // records x2 for future queries
290 bool dep_seen_x3 = note_dep_seen(dept, x3); // records x3 for future queries
291 if (dep_seen_x1 && dep_seen_x2 && dep_seen_x3) {
292 // look in this bucket for redundant assertions
293 const int stride = 4;
294 for (int i = deps->length(); (i -= stride) >= 0; ) {
295 ciBaseObject* y1 = deps->at(i+1);
296 ciBaseObject* y2 = deps->at(i+2);
297 ciBaseObject* y3 = deps->at(i+3);
298 if (x1 == y1 && x2 == y2 && x3 == y3) { // same subjects; check the context
299 if (maybe_merge_ctxk(deps, i+0, ctxk)) {
300 return;
301 }
302 }
303 }
304 }
305 // append the assertion in the correct bucket:
306 deps->append(ctxk);
307 deps->append(x1);
308 deps->append(x2);
309 deps->append(x3);
310 }
311
312 #if INCLUDE_JVMCI
313 bool Dependencies::maybe_merge_ctxk(GrowableArray<DepValue>* deps,
314 int ctxk_i, DepValue ctxk2_dv) {
315 Klass* ctxk1 = deps->at(ctxk_i).as_klass(_oop_recorder);
316 Klass* ctxk2 = ctxk2_dv.as_klass(_oop_recorder);
317 if (ctxk2->is_subtype_of(ctxk1)) {
318 return true; // success, and no need to change
319 } else if (ctxk1->is_subtype_of(ctxk2)) {
320 // new context class fully subsumes previous one
321 deps->at_put(ctxk_i, ctxk2_dv);
322 return true;
323 } else {
324 return false;
325 }
326 }
327
328 void Dependencies::assert_common_1(DepType dept, DepValue x) {
329 assert(dep_args(dept) == 1, "sanity");
330 //log_dependency(dept, x);
331 GrowableArray<DepValue>* deps = _dep_values[dept];
332
333 // see if the same (or a similar) dep is already recorded
334 if (note_dep_seen(dept, x)) {
335 assert(deps->find(x) >= 0, "sanity");
336 } else {
337 deps->append(x);
338 }
339 }
340
341 void Dependencies::assert_common_2(DepType dept,
342 DepValue x0, DepValue x1) {
343 assert(dep_args(dept) == 2, "sanity");
344 //log_dependency(dept, x0, x1);
345 GrowableArray<DepValue>* deps = _dep_values[dept];
346
347 // see if the same (or a similar) dep is already recorded
348 bool has_ctxk = has_explicit_context_arg(dept);
349 if (has_ctxk) {
350 assert(dep_context_arg(dept) == 0, "sanity");
351 if (note_dep_seen(dept, x1)) {
352 // look in this bucket for redundant assertions
353 const int stride = 2;
354 for (int i = deps->length(); (i -= stride) >= 0; ) {
355 DepValue y1 = deps->at(i+1);
356 if (x1 == y1) { // same subject; check the context
357 if (maybe_merge_ctxk(deps, i+0, x0)) {
358 return;
359 }
360 }
361 }
362 }
363 } else {
364 bool dep_seen_x0 = note_dep_seen(dept, x0); // records x0 for future queries
365 bool dep_seen_x1 = note_dep_seen(dept, x1); // records x1 for future queries
366 if (dep_seen_x0 && dep_seen_x1) {
367 // look in this bucket for redundant assertions
368 const int stride = 2;
369 for (int i = deps->length(); (i -= stride) >= 0; ) {
370 DepValue y0 = deps->at(i+0);
371 DepValue y1 = deps->at(i+1);
372 if (x0 == y0 && x1 == y1) {
373 return;
374 }
375 }
376 }
377 }
378
379 // append the assertion in the correct bucket:
380 deps->append(x0);
381 deps->append(x1);
382 }
383 #endif // INCLUDE_JVMCI
384
385 /// Support for encoding dependencies into an nmethod:
386
387 void Dependencies::copy_to(nmethod* nm) {
388 address beg = nm->dependencies_begin();
389 address end = nm->dependencies_end();
390 guarantee(end - beg >= (ptrdiff_t) size_in_bytes(), "bad sizing");
391 Copy::disjoint_words((HeapWord*) content_bytes(),
392 (HeapWord*) beg,
393 size_in_bytes() / sizeof(HeapWord));
394 assert(size_in_bytes() % sizeof(HeapWord) == 0, "copy by words");
395 }
396
397 static int sort_dep(ciBaseObject** p1, ciBaseObject** p2, int narg) {
398 for (int i = 0; i < narg; i++) {
399 int diff = p1[i]->ident() - p2[i]->ident();
400 if (diff != 0) return diff;
401 }
402 return 0;
403 }
404 static int sort_dep_arg_1(ciBaseObject** p1, ciBaseObject** p2)
405 { return sort_dep(p1, p2, 1); }
406 static int sort_dep_arg_2(ciBaseObject** p1, ciBaseObject** p2)
407 { return sort_dep(p1, p2, 2); }
408 static int sort_dep_arg_3(ciBaseObject** p1, ciBaseObject** p2)
409 { return sort_dep(p1, p2, 3); }
410 static int sort_dep_arg_4(ciBaseObject** p1, ciBaseObject** p2)
411 { return sort_dep(p1, p2, 4); }
412
413 #if INCLUDE_JVMCI
414 // metadata deps are sorted before object deps
415 static int sort_dep_value(Dependencies::DepValue* p1, Dependencies::DepValue* p2, int narg) {
416 for (int i = 0; i < narg; i++) {
417 int diff = p1[i].sort_key() - p2[i].sort_key();
418 if (diff != 0) return diff;
419 }
420 return 0;
421 }
422 static int sort_dep_value_arg_1(Dependencies::DepValue* p1, Dependencies::DepValue* p2)
423 { return sort_dep_value(p1, p2, 1); }
424 static int sort_dep_value_arg_2(Dependencies::DepValue* p1, Dependencies::DepValue* p2)
425 { return sort_dep_value(p1, p2, 2); }
426 static int sort_dep_value_arg_3(Dependencies::DepValue* p1, Dependencies::DepValue* p2)
427 { return sort_dep_value(p1, p2, 3); }
428 #endif // INCLUDE_JVMCI
429
430 void Dependencies::sort_all_deps() {
431 #if INCLUDE_JVMCI
432 if (_using_dep_values) {
433 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
434 DepType dept = (DepType)deptv;
435 GrowableArray<DepValue>* deps = _dep_values[dept];
436 if (deps->length() <= 1) continue;
437 switch (dep_args(dept)) {
438 case 1: deps->sort(sort_dep_value_arg_1, 1); break;
439 case 2: deps->sort(sort_dep_value_arg_2, 2); break;
440 case 3: deps->sort(sort_dep_value_arg_3, 3); break;
441 default: ShouldNotReachHere(); break;
442 }
443 }
444 return;
445 }
446 #endif // INCLUDE_JVMCI
447 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
448 DepType dept = (DepType)deptv;
449 GrowableArray<ciBaseObject*>* deps = _deps[dept];
450 if (deps->length() <= 1) continue;
451 switch (dep_args(dept)) {
452 case 1: deps->sort(sort_dep_arg_1, 1); break;
453 case 2: deps->sort(sort_dep_arg_2, 2); break;
454 case 3: deps->sort(sort_dep_arg_3, 3); break;
455 case 4: deps->sort(sort_dep_arg_4, 4); break;
456 default: ShouldNotReachHere(); break;
457 }
458 }
459 }
460
461 size_t Dependencies::estimate_size_in_bytes() {
462 size_t est_size = 100;
463 #if INCLUDE_JVMCI
464 if (_using_dep_values) {
465 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
466 DepType dept = (DepType)deptv;
467 GrowableArray<DepValue>* deps = _dep_values[dept];
468 est_size += deps->length() * 2; // tags and argument(s)
469 }
470 return est_size;
471 }
472 #endif // INCLUDE_JVMCI
473 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
474 DepType dept = (DepType)deptv;
475 GrowableArray<ciBaseObject*>* deps = _deps[dept];
476 est_size += deps->length()*2; // tags and argument(s)
477 }
478 return est_size;
479 }
480
481 ciKlass* Dependencies::ctxk_encoded_as_null(DepType dept, ciBaseObject* x) {
482 switch (dept) {
483 case unique_concrete_method_2:
484 case unique_concrete_method_4:
485 return x->as_metadata()->as_method()->holder();
486 default:
487 return nullptr; // let nullptr be nullptr
488 }
489 }
490
491 Klass* Dependencies::ctxk_encoded_as_null(DepType dept, Metadata* x) {
492 assert(must_be_in_vm(), "raw oops here");
493 switch (dept) {
494 case unique_concrete_method_2:
495 case unique_concrete_method_4:
496 assert(x->is_method(), "sanity");
497 return ((Method*)x)->method_holder();
498 default:
499 return nullptr; // let nullptr be nullptr
500 }
501 }
502
503 void Dependencies::encode_content_bytes() {
504 sort_all_deps();
505
506 // cast is safe, no deps can overflow INT_MAX
507 CompressedWriteStream bytes((int)estimate_size_in_bytes());
508
509 #if INCLUDE_JVMCI
510 if (_using_dep_values) {
511 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
512 DepType dept = (DepType)deptv;
513 GrowableArray<DepValue>* deps = _dep_values[dept];
514 if (deps->length() == 0) continue;
515 int stride = dep_args(dept);
516 int ctxkj = dep_context_arg(dept); // -1 if no context arg
517 assert(stride > 0, "sanity");
518 for (int i = 0; i < deps->length(); i += stride) {
519 jbyte code_byte = (jbyte)dept;
520 int skipj = -1;
521 if (ctxkj >= 0 && ctxkj+1 < stride) {
522 Klass* ctxk = deps->at(i+ctxkj+0).as_klass(_oop_recorder);
523 DepValue x = deps->at(i+ctxkj+1); // following argument
524 if (ctxk == ctxk_encoded_as_null(dept, x.as_metadata(_oop_recorder))) {
525 skipj = ctxkj; // we win: maybe one less oop to keep track of
526 code_byte |= default_context_type_bit;
527 }
528 }
529 bytes.write_byte(code_byte);
530 for (int j = 0; j < stride; j++) {
531 if (j == skipj) continue;
532 DepValue v = deps->at(i+j);
533 int idx = v.index();
534 bytes.write_int(idx);
535 }
536 }
537 }
538 } else {
539 #endif // INCLUDE_JVMCI
540 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
541 DepType dept = (DepType)deptv;
542 GrowableArray<ciBaseObject*>* deps = _deps[dept];
543 if (deps->length() == 0) continue;
544 int stride = dep_args(dept);
545 int ctxkj = dep_context_arg(dept); // -1 if no context arg
546 assert(stride > 0, "sanity");
547 for (int i = 0; i < deps->length(); i += stride) {
548 jbyte code_byte = (jbyte)dept;
549 int skipj = -1;
550 if (ctxkj >= 0 && ctxkj+1 < stride) {
551 ciKlass* ctxk = deps->at(i+ctxkj+0)->as_metadata()->as_klass();
552 ciBaseObject* x = deps->at(i+ctxkj+1); // following argument
553 if (ctxk == ctxk_encoded_as_null(dept, x)) {
554 skipj = ctxkj; // we win: maybe one less oop to keep track of
555 code_byte |= default_context_type_bit;
556 }
557 }
558 bytes.write_byte(code_byte);
559 for (int j = 0; j < stride; j++) {
560 if (j == skipj) continue;
561 ciBaseObject* v = deps->at(i+j);
562 int idx;
563 if (v->is_object()) {
564 idx = _oop_recorder->find_index(v->as_object()->constant_encoding());
565 } else {
566 ciMetadata* meta = v->as_metadata();
567 idx = _oop_recorder->find_index(meta->constant_encoding());
568 }
569 bytes.write_int(idx);
570 }
571 }
572 }
573 #if INCLUDE_JVMCI
574 }
575 #endif
576
577 // write a sentinel byte to mark the end
578 bytes.write_byte(end_marker);
579
580 // round it out to a word boundary
581 while (bytes.position() % sizeof(HeapWord) != 0) {
582 bytes.write_byte(end_marker);
583 }
584
585 // check whether the dept byte encoding really works
586 assert((jbyte)default_context_type_bit != 0, "byte overflow");
587
588 _content_bytes = bytes.buffer();
589 _size_in_bytes = bytes.position();
590 }
591
592
593 const char* Dependencies::_dep_name[TYPE_LIMIT] = {
594 "end_marker",
595 "evol_method",
596 "leaf_type",
597 "abstract_with_unique_concrete_subtype",
598 "unique_concrete_method_2",
599 "unique_concrete_method_4",
600 "unique_implementor",
601 "no_finalizable_subclasses",
602 "call_site_target_value"
603 };
604
605 int Dependencies::_dep_args[TYPE_LIMIT] = {
606 -1,// end_marker
607 1, // evol_method m
608 1, // leaf_type ctxk
609 2, // abstract_with_unique_concrete_subtype ctxk, k
610 2, // unique_concrete_method_2 ctxk, m
611 4, // unique_concrete_method_4 ctxk, m, resolved_klass, resolved_method
612 2, // unique_implementor ctxk, implementor
613 1, // no_finalizable_subclasses ctxk
614 2 // call_site_target_value call_site, method_handle
615 };
616
617 const char* Dependencies::dep_name(Dependencies::DepType dept) {
618 if (!dept_in_mask(dept, all_types)) return "?bad-dep?";
619 return _dep_name[dept];
620 }
621
622 int Dependencies::dep_args(Dependencies::DepType dept) {
623 if (!dept_in_mask(dept, all_types)) return -1;
624 return _dep_args[dept];
625 }
626
627 void Dependencies::check_valid_dependency_type(DepType dept) {
628 guarantee(FIRST_TYPE <= dept && dept < TYPE_LIMIT, "invalid dependency type: %d", (int) dept);
629 }
630
631 Dependencies::DepType Dependencies::validate_dependencies(CompileTask* task, char** failure_detail) {
632 int klass_violations = 0;
633 DepType result = end_marker;
634 for (Dependencies::DepStream deps(this); deps.next(); ) {
635 Klass* witness = deps.check_dependency();
636 if (witness != nullptr) {
637 if (klass_violations == 0) {
638 result = deps.type();
639 if (failure_detail != nullptr && klass_violations == 0) {
640 // Use a fixed size buffer to prevent the string stream from
641 // resizing in the context of an inner resource mark.
642 char* buffer = NEW_RESOURCE_ARRAY(char, O_BUFLEN);
643 stringStream st(buffer, O_BUFLEN);
644 deps.print_dependency(&st, witness, true);
645 *failure_detail = st.as_string();
646 }
647 }
648 klass_violations++;
649 if (xtty == nullptr) {
650 // If we're not logging then a single violation is sufficient,
651 // otherwise we want to log all the dependences which were
652 // violated.
653 break;
654 }
655 }
656 }
657
658 return result;
659 }
660
661 // for the sake of the compiler log, print out current dependencies:
662 void Dependencies::log_all_dependencies() {
663 if (log() == nullptr) return;
664 ResourceMark rm;
665 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
666 DepType dept = (DepType)deptv;
667 GrowableArray<ciBaseObject*>* deps = _deps[dept];
668 int deplen = deps->length();
669 if (deplen == 0) {
670 continue;
671 }
672 int stride = dep_args(dept);
673 GrowableArray<ciBaseObject*>* ciargs = new GrowableArray<ciBaseObject*>(stride);
674 for (int i = 0; i < deps->length(); i += stride) {
675 for (int j = 0; j < stride; j++) {
676 // flush out the identities before printing
677 ciargs->push(deps->at(i+j));
678 }
679 write_dependency_to(log(), dept, ciargs);
680 ciargs->clear();
681 }
682 guarantee(deplen == deps->length(), "deps array cannot grow inside nested ResoureMark scope");
683 }
684 }
685
686 void Dependencies::write_dependency_to(CompileLog* log,
687 DepType dept,
688 GrowableArray<DepArgument>* args,
689 Klass* witness) {
690 if (log == nullptr) {
691 return;
692 }
693 ResourceMark rm;
694 ciEnv* env = ciEnv::current();
695 GrowableArray<ciBaseObject*>* ciargs = new GrowableArray<ciBaseObject*>(args->length());
696 for (GrowableArrayIterator<DepArgument> it = args->begin(); it != args->end(); ++it) {
697 DepArgument arg = *it;
698 if (arg.is_oop()) {
699 ciargs->push(env->get_object(arg.oop_value()));
700 } else {
701 ciargs->push(env->get_metadata(arg.metadata_value()));
702 }
703 }
704 int argslen = ciargs->length();
705 Dependencies::write_dependency_to(log, dept, ciargs, witness);
706 guarantee(argslen == ciargs->length(), "ciargs array cannot grow inside nested ResoureMark scope");
707 }
708
709 void Dependencies::write_dependency_to(CompileLog* log,
710 DepType dept,
711 GrowableArray<ciBaseObject*>* args,
712 Klass* witness) {
713 if (log == nullptr) {
714 return;
715 }
716 ResourceMark rm;
717 GrowableArray<int>* argids = new GrowableArray<int>(args->length());
718 for (GrowableArrayIterator<ciBaseObject*> it = args->begin(); it != args->end(); ++it) {
719 ciBaseObject* obj = *it;
720 if (obj->is_object()) {
721 argids->push(log->identify(obj->as_object()));
722 } else {
723 argids->push(log->identify(obj->as_metadata()));
724 }
725 }
726 if (witness != nullptr) {
727 log->begin_elem("dependency_failed");
728 } else {
729 log->begin_elem("dependency");
730 }
731 log->print(" type='%s'", dep_name(dept));
732 const int ctxkj = dep_context_arg(dept); // -1 if no context arg
733 if (ctxkj >= 0 && ctxkj < argids->length()) {
734 log->print(" ctxk='%d'", argids->at(ctxkj));
735 }
736 // write remaining arguments, if any.
737 for (int j = 0; j < argids->length(); j++) {
738 if (j == ctxkj) continue; // already logged
739 if (j == 1) {
740 log->print( " x='%d'", argids->at(j));
741 } else {
742 log->print(" x%d='%d'", j, argids->at(j));
743 }
744 }
745 if (witness != nullptr) {
746 log->object("witness", witness);
747 log->stamp();
748 }
749 log->end_elem();
750 }
751
752 void Dependencies::write_dependency_to(xmlStream* xtty,
753 DepType dept,
754 GrowableArray<DepArgument>* args,
755 Klass* witness) {
756 if (xtty == nullptr) {
757 return;
758 }
759 Thread* thread = Thread::current();
760 HandleMark rm(thread);
761 ttyLocker ttyl;
762 int ctxkj = dep_context_arg(dept); // -1 if no context arg
763 if (witness != nullptr) {
764 xtty->begin_elem("dependency_failed");
765 } else {
766 xtty->begin_elem("dependency");
767 }
768 xtty->print(" type='%s'", dep_name(dept));
769 if (ctxkj >= 0) {
770 xtty->object("ctxk", args->at(ctxkj).metadata_value());
771 }
772 // write remaining arguments, if any.
773 for (int j = 0; j < args->length(); j++) {
774 if (j == ctxkj) continue; // already logged
775 DepArgument arg = args->at(j);
776 if (j == 1) {
777 if (arg.is_oop()) {
778 xtty->object("x", Handle(thread, arg.oop_value()));
779 } else {
780 xtty->object("x", arg.metadata_value());
781 }
782 } else {
783 char xn[12];
784 os::snprintf_checked(xn, sizeof(xn), "x%d", j);
785 if (arg.is_oop()) {
786 xtty->object(xn, Handle(thread, arg.oop_value()));
787 } else {
788 xtty->object(xn, arg.metadata_value());
789 }
790 }
791 }
792 if (witness != nullptr) {
793 xtty->object("witness", witness);
794 xtty->stamp();
795 }
796 xtty->end_elem();
797 }
798
799 void Dependencies::print_dependency(DepType dept, GrowableArray<DepArgument>* args,
800 Klass* witness, outputStream* st) {
801 ResourceMark rm;
802 ttyLocker ttyl; // keep the following output all in one block
803 st->print_cr("%s of type %s",
804 (witness == nullptr)? "Dependency": "Failed dependency",
805 dep_name(dept));
806 // print arguments
807 int ctxkj = dep_context_arg(dept); // -1 if no context arg
808 for (int j = 0; j < args->length(); j++) {
809 DepArgument arg = args->at(j);
810 bool put_star = false;
811 if (arg.is_null()) continue;
812 const char* what;
813 if (j == ctxkj) {
814 assert(arg.is_metadata(), "must be");
815 what = "context";
816 put_star = !Dependencies::is_concrete_klass((Klass*)arg.metadata_value());
817 } else if (arg.is_method()) {
818 what = "method ";
819 put_star = !Dependencies::is_concrete_method((Method*)arg.metadata_value(), nullptr);
820 } else if (arg.is_klass()) {
821 what = "class ";
822 } else {
823 what = "object ";
824 }
825 st->print(" %s = %s", what, (put_star? "*": ""));
826 if (arg.is_klass()) {
827 st->print("%s", ((Klass*)arg.metadata_value())->external_name());
828 } else if (arg.is_method()) {
829 ((Method*)arg.metadata_value())->print_value_on(st);
830 } else if (arg.is_oop()) {
831 arg.oop_value()->print_value_on(st);
832 } else {
833 ShouldNotReachHere(); // Provide impl for this type.
834 }
835
836 st->cr();
837 }
838 if (witness != nullptr) {
839 bool put_star = !Dependencies::is_concrete_klass(witness);
840 st->print_cr(" witness = %s%s",
841 (put_star? "*": ""),
842 witness->external_name());
843 }
844 }
845
846 void Dependencies::DepStream::log_dependency(Klass* witness) {
847 if (_deps == nullptr && xtty == nullptr) return; // fast cutout for runtime
848 ResourceMark rm;
849 const int nargs = argument_count();
850 GrowableArray<DepArgument>* args = new GrowableArray<DepArgument>(nargs);
851 for (int j = 0; j < nargs; j++) {
852 if (is_oop_argument(j)) {
853 args->push(argument_oop(j));
854 } else {
855 args->push(argument(j));
856 }
857 }
858 int argslen = args->length();
859 if (_deps != nullptr && _deps->log() != nullptr) {
860 if (ciEnv::current() != nullptr) {
861 Dependencies::write_dependency_to(_deps->log(), type(), args, witness);
862 } else {
863 // Treat the CompileLog as an xmlstream instead
864 Dependencies::write_dependency_to((xmlStream*)_deps->log(), type(), args, witness);
865 }
866 } else {
867 Dependencies::write_dependency_to(xtty, type(), args, witness);
868 }
869 guarantee(argslen == args->length(), "args array cannot grow inside nested ResoureMark scope");
870 }
871
872 void Dependencies::DepStream::print_dependency(outputStream* st, Klass* witness, bool verbose) {
873 ResourceMark rm;
874 int nargs = argument_count();
875 GrowableArray<DepArgument>* args = new GrowableArray<DepArgument>(nargs);
876 for (int j = 0; j < nargs; j++) {
877 if (is_oop_argument(j)) {
878 args->push(argument_oop(j));
879 } else {
880 args->push(argument(j));
881 }
882 }
883 int argslen = args->length();
884 Dependencies::print_dependency(type(), args, witness, st);
885 if (verbose) {
886 if (_code != nullptr) {
887 st->print(" code: ");
888 _code->print_value_on(st);
889 st->cr();
890 }
891 }
892 guarantee(argslen == args->length(), "args array cannot grow inside nested ResoureMark scope");
893 }
894
895
896 /// Dependency stream support (decodes dependencies from an nmethod):
897
898 #ifdef ASSERT
899 void Dependencies::DepStream::initial_asserts(size_t byte_limit) {
900 assert(must_be_in_vm(), "raw oops here");
901 _byte_limit = byte_limit;
902 _type = (DepType)(end_marker-1); // defeat "already at end" assert
903 assert((_code!=nullptr) + (_deps!=nullptr) == 1, "one or t'other");
904 }
905 #endif //ASSERT
906
907 bool Dependencies::DepStream::next() {
908 assert(_type != end_marker, "already at end");
909 if (_bytes.position() == 0 && _code != nullptr
910 && _code->dependencies_size() == 0) {
911 // Method has no dependencies at all.
912 return false;
913 }
914 int code_byte = (_bytes.read_byte() & 0xFF);
915 if (code_byte == end_marker) {
916 DEBUG_ONLY(_type = end_marker);
917 return false;
918 } else {
919 int ctxk_bit = (code_byte & Dependencies::default_context_type_bit);
920 code_byte -= ctxk_bit;
921 DepType dept = (DepType)code_byte;
922 _type = dept;
923 Dependencies::check_valid_dependency_type(dept);
924 int stride = _dep_args[dept];
925 assert(stride == dep_args(dept), "sanity");
926 int skipj = -1;
927 if (ctxk_bit != 0) {
928 skipj = 0; // currently the only context argument is at zero
929 assert(skipj == dep_context_arg(dept), "zero arg always ctxk");
930 }
931 for (int j = 0; j < stride; j++) {
932 _xi[j] = (j == skipj)? 0: _bytes.read_int();
933 }
934 DEBUG_ONLY(_xi[stride] = -1); // help detect overruns
935 return true;
936 }
937 }
938
939 inline Metadata* Dependencies::DepStream::recorded_metadata_at(int i) {
940 Metadata* o = nullptr;
941 if (_code != nullptr) {
942 o = _code->metadata_at(i);
943 } else {
944 o = _deps->oop_recorder()->metadata_at(i);
945 }
946 return o;
947 }
948
949 inline oop Dependencies::DepStream::recorded_oop_at(int i) {
950 return (_code != nullptr)
951 ? _code->oop_at(i)
952 : JNIHandles::resolve(_deps->oop_recorder()->oop_at(i));
953 }
954
955 Metadata* Dependencies::DepStream::argument(int i) {
956 Metadata* result = recorded_metadata_at(argument_index(i));
957
958 if (result == nullptr) { // Explicit context argument can be compressed
959 int ctxkj = dep_context_arg(type()); // -1 if no explicit context arg
960 if (ctxkj >= 0 && i == ctxkj && ctxkj+1 < argument_count()) {
961 result = ctxk_encoded_as_null(type(), argument(ctxkj+1));
962 }
963 }
964
965 assert(result == nullptr || result->is_klass() || result->is_method(), "must be");
966 return result;
967 }
968
969 /**
970 * Returns a unique identifier for each dependency argument.
971 */
972 uintptr_t Dependencies::DepStream::get_identifier(int i) {
973 if (is_oop_argument(i)) {
974 return (uintptr_t)(oopDesc*)argument_oop(i);
975 } else {
976 return (uintptr_t)argument(i);
977 }
978 }
979
980 oop Dependencies::DepStream::argument_oop(int i) {
981 oop result = recorded_oop_at(argument_index(i));
982 assert(oopDesc::is_oop_or_null(result), "must be");
983 return result;
984 }
985
986 InstanceKlass* Dependencies::DepStream::context_type() {
987 assert(must_be_in_vm(), "raw oops here");
988
989 // Most dependencies have an explicit context type argument.
990 {
991 int ctxkj = dep_context_arg(type()); // -1 if no explicit context arg
992 if (ctxkj >= 0) {
993 Metadata* k = argument(ctxkj);
994 assert(k != nullptr && k->is_klass(), "type check");
995 return InstanceKlass::cast((Klass*)k);
996 }
997 }
998
999 // Some dependencies are using the klass of the first object
1000 // argument as implicit context type.
1001 {
1002 int ctxkj = dep_implicit_context_arg(type());
1003 if (ctxkj >= 0) {
1004 Klass* k = argument_oop(ctxkj)->klass();
1005 assert(k != nullptr, "type check");
1006 return InstanceKlass::cast(k);
1007 }
1008 }
1009
1010 // And some dependencies don't have a context type at all,
1011 // e.g. evol_method.
1012 return nullptr;
1013 }
1014
1015 // ----------------- DependencySignature --------------------------------------
1016 bool DependencySignature::equals(DependencySignature const& s1, DependencySignature const& s2) {
1017 if ((s1.type() != s2.type()) || (s1.args_count() != s2.args_count())) {
1018 return false;
1019 }
1020
1021 for (int i = 0; i < s1.args_count(); i++) {
1022 if (s1.arg(i) != s2.arg(i)) {
1023 return false;
1024 }
1025 }
1026 return true;
1027 }
1028
1029 /// Checking dependencies
1030
1031 // This hierarchy walker inspects subtypes of a given type, trying to find a "bad" class which breaks a dependency.
1032 // Such a class is called a "witness" to the broken dependency.
1033 // While searching around, we ignore "participants", which are already known to the dependency.
1034 class AbstractClassHierarchyWalker {
1035 public:
1036 enum { PARTICIPANT_LIMIT = 3 };
1037
1038 private:
1039 // if non-zero, tells how many witnesses to convert to participants
1040 uint _record_witnesses;
1041
1042 // special classes which are not allowed to be witnesses:
1043 Klass* _participants[PARTICIPANT_LIMIT+1];
1044 uint _num_participants;
1045
1046 #ifdef ASSERT
1047 uint _nof_requests; // one-shot walker
1048 #endif // ASSERT
1049
1050 static PerfCounter* _perf_find_witness_anywhere_calls_count;
1051 static PerfCounter* _perf_find_witness_anywhere_steps_count;
1052 static PerfCounter* _perf_find_witness_in_calls_count;
1053
1054 protected:
1055 virtual Klass* find_witness_in(KlassDepChange& changes) = 0;
1056 virtual Klass* find_witness_anywhere(InstanceKlass* context_type) = 0;
1057
1058 AbstractClassHierarchyWalker(Klass* participant) : _record_witnesses(0), _num_participants(0)
1059 #ifdef ASSERT
1060 , _nof_requests(0)
1061 #endif // ASSERT
1062 {
1063 for (uint i = 0; i < PARTICIPANT_LIMIT+1; i++) {
1064 _participants[i] = nullptr;
1065 }
1066 if (participant != nullptr) {
1067 add_participant(participant);
1068 }
1069 }
1070
1071 bool is_participant(Klass* k) {
1072 for (uint i = 0; i < _num_participants; i++) {
1073 if (_participants[i] == k) {
1074 return true;
1075 }
1076 }
1077 return false;
1078 }
1079
1080 bool record_witness(Klass* witness) {
1081 if (_record_witnesses > 0) {
1082 --_record_witnesses;
1083 add_participant(witness);
1084 return false; // not a witness
1085 } else {
1086 return true; // is a witness
1087 }
1088 }
1089
1090 class CountingClassHierarchyIterator : public ClassHierarchyIterator {
1091 private:
1092 jlong _nof_steps;
1093 public:
1094 CountingClassHierarchyIterator(InstanceKlass* root) : ClassHierarchyIterator(root), _nof_steps(0) {}
1095
1096 void next() {
1097 _nof_steps++;
1098 ClassHierarchyIterator::next();
1099 }
1100
1101 ~CountingClassHierarchyIterator() {
1102 if (UsePerfData) {
1103 _perf_find_witness_anywhere_steps_count->inc(_nof_steps);
1104 }
1105 }
1106 };
1107
1108 public:
1109 uint num_participants() { return _num_participants; }
1110 Klass* participant(uint n) {
1111 assert(n <= _num_participants, "oob");
1112 if (n < _num_participants) {
1113 return _participants[n];
1114 } else {
1115 return nullptr;
1116 }
1117 }
1118
1119 void add_participant(Klass* participant) {
1120 assert(!is_participant(participant), "sanity");
1121 assert(_num_participants + _record_witnesses < PARTICIPANT_LIMIT, "oob");
1122 uint np = _num_participants++;
1123 _participants[np] = participant;
1124 }
1125
1126 void record_witnesses(uint add) {
1127 if (add > PARTICIPANT_LIMIT) add = PARTICIPANT_LIMIT;
1128 assert(_num_participants + add < PARTICIPANT_LIMIT, "oob");
1129 _record_witnesses = add;
1130 }
1131
1132 Klass* find_witness(InstanceKlass* context_type, KlassDepChange* changes = nullptr);
1133
1134 static void init();
1135 static void print_statistics();
1136 };
1137
1138 PerfCounter* AbstractClassHierarchyWalker::_perf_find_witness_anywhere_calls_count = nullptr;
1139 PerfCounter* AbstractClassHierarchyWalker::_perf_find_witness_anywhere_steps_count = nullptr;
1140 PerfCounter* AbstractClassHierarchyWalker::_perf_find_witness_in_calls_count = nullptr;
1141
1142 void AbstractClassHierarchyWalker::init() {
1143 if (UsePerfData) {
1144 EXCEPTION_MARK;
1145 _perf_find_witness_anywhere_calls_count =
1146 PerfDataManager::create_counter(SUN_CI, "findWitnessAnywhere", PerfData::U_Events, CHECK);
1147 _perf_find_witness_anywhere_steps_count =
1148 PerfDataManager::create_counter(SUN_CI, "findWitnessAnywhereSteps", PerfData::U_Events, CHECK);
1149 _perf_find_witness_in_calls_count =
1150 PerfDataManager::create_counter(SUN_CI, "findWitnessIn", PerfData::U_Events, CHECK);
1151 }
1152 }
1153
1154 Klass* AbstractClassHierarchyWalker::find_witness(InstanceKlass* context_type, KlassDepChange* changes) {
1155 // Current thread must be in VM (not native mode, as in CI):
1156 assert(must_be_in_vm(), "raw oops here");
1157 // Must not move the class hierarchy during this check:
1158 assert_locked_or_safepoint(Compile_lock);
1159 assert(_nof_requests++ == 0, "repeated requests are not supported");
1160
1161 assert(changes == nullptr || changes->involves_context(context_type), "irrelevant dependency");
1162
1163 // (Note: Interfaces do not have subclasses.)
1164 // If it is an interface, search its direct implementors.
1165 // (Their subclasses are additional indirect implementors. See InstanceKlass::add_implementor().)
1166 if (context_type->is_interface()) {
1167 int nof_impls = context_type->nof_implementors();
1168 if (nof_impls == 0) {
1169 return nullptr; // no implementors
1170 } else if (nof_impls == 1) { // unique implementor
1171 assert(context_type != context_type->implementor(), "not unique");
1172 context_type = context_type->implementor();
1173 } else { // nof_impls >= 2
1174 // Avoid this case: *I.m > { A.m, C }; B.m > C
1175 // Here, I.m has 2 concrete implementations, but m appears unique
1176 // as A.m, because the search misses B.m when checking C.
1177 // The inherited method B.m was getting missed by the walker
1178 // when interface 'I' was the starting point.
1179 // %%% Until this is fixed more systematically, bail out.
1180 return context_type;
1181 }
1182 }
1183 assert(!context_type->is_interface(), "no interfaces allowed");
1184
1185 if (changes != nullptr) {
1186 if (UsePerfData) {
1187 _perf_find_witness_in_calls_count->inc();
1188 }
1189 return find_witness_in(*changes);
1190 } else {
1191 if (UsePerfData) {
1192 _perf_find_witness_anywhere_calls_count->inc();
1193 }
1194 return find_witness_anywhere(context_type);
1195 }
1196 }
1197
1198 class ConcreteSubtypeFinder : public AbstractClassHierarchyWalker {
1199 private:
1200 bool is_witness(Klass* k);
1201
1202 protected:
1203 virtual Klass* find_witness_in(KlassDepChange& changes);
1204 virtual Klass* find_witness_anywhere(InstanceKlass* context_type);
1205
1206 public:
1207 ConcreteSubtypeFinder(Klass* participant = nullptr) : AbstractClassHierarchyWalker(participant) {}
1208 };
1209
1210 bool ConcreteSubtypeFinder::is_witness(Klass* k) {
1211 if (Dependencies::is_concrete_klass(k)) {
1212 return record_witness(k); // concrete subtype
1213 } else {
1214 return false; // not a concrete class
1215 }
1216 }
1217
1218 Klass* ConcreteSubtypeFinder::find_witness_in(KlassDepChange& changes) {
1219 // When looking for unexpected concrete types, do not look beneath expected ones:
1220 // * CX > CC > C' is OK, even if C' is new.
1221 // * CX > { CC, C' } is not OK if C' is new, and C' is the witness.
1222 Klass* new_type = changes.as_new_klass_change()->new_type();
1223 assert(!is_participant(new_type), "only old classes are participants");
1224 // If the new type is a subtype of a participant, we are done.
1225 for (uint i = 0; i < num_participants(); i++) {
1226 if (changes.involves_context(participant(i))) {
1227 // new guy is protected from this check by previous participant
1228 return nullptr;
1229 }
1230 }
1231 if (is_witness(new_type)) {
1232 return new_type;
1233 }
1234 // No witness found. The dependency remains unbroken.
1235 return nullptr;
1236 }
1237
1238 Klass* ConcreteSubtypeFinder::find_witness_anywhere(InstanceKlass* context_type) {
1239 for (CountingClassHierarchyIterator iter(context_type); !iter.done(); iter.next()) {
1240 Klass* sub = iter.klass();
1241 // Do not report participant types.
1242 if (is_participant(sub)) {
1243 // Don't walk beneath a participant since it hides witnesses.
1244 iter.skip_subclasses();
1245 } else if (is_witness(sub)) {
1246 return sub; // found a witness
1247 }
1248 }
1249 // No witness found. The dependency remains unbroken.
1250 return nullptr;
1251 }
1252
1253 class ConcreteMethodFinder : public AbstractClassHierarchyWalker {
1254 private:
1255 Symbol* _name;
1256 Symbol* _signature;
1257
1258 // cache of method lookups
1259 Method* _found_methods[PARTICIPANT_LIMIT+1];
1260
1261 bool is_witness(Klass* k);
1262
1263 protected:
1264 virtual Klass* find_witness_in(KlassDepChange& changes);
1265 virtual Klass* find_witness_anywhere(InstanceKlass* context_type);
1266
1267 public:
1268 bool witnessed_reabstraction_in_supers(Klass* k);
1269
1270 ConcreteMethodFinder(Method* m, Klass* participant = nullptr) : AbstractClassHierarchyWalker(participant) {
1271 assert(m != nullptr && m->is_method(), "sanity");
1272 _name = m->name();
1273 _signature = m->signature();
1274
1275 for (int i = 0; i < PARTICIPANT_LIMIT+1; i++) {
1276 _found_methods[i] = nullptr;
1277 }
1278 }
1279
1280 // Note: If n==num_participants, returns nullptr.
1281 Method* found_method(uint n) {
1282 assert(n <= num_participants(), "oob");
1283 Method* fm = _found_methods[n];
1284 assert(n == num_participants() || fm != nullptr, "proper usage");
1285 if (fm != nullptr && fm->method_holder() != participant(n)) {
1286 // Default methods from interfaces can be added to classes. In
1287 // that case the holder of the method is not the class but the
1288 // interface where it's defined.
1289 assert(fm->is_default_method(), "sanity");
1290 return nullptr;
1291 }
1292 return fm;
1293 }
1294
1295 void add_participant(Klass* participant) {
1296 AbstractClassHierarchyWalker::add_participant(participant);
1297 _found_methods[num_participants()] = nullptr;
1298 }
1299
1300 bool record_witness(Klass* witness, Method* m) {
1301 _found_methods[num_participants()] = m;
1302 return AbstractClassHierarchyWalker::record_witness(witness);
1303 }
1304
1305 private:
1306 static PerfCounter* _perf_find_witness_anywhere_calls_count;
1307 static PerfCounter* _perf_find_witness_anywhere_steps_count;
1308 static PerfCounter* _perf_find_witness_in_calls_count;
1309
1310 public:
1311 static void init();
1312 static void print_statistics();
1313 };
1314
1315 bool ConcreteMethodFinder::is_witness(Klass* k) {
1316 if (is_participant(k)) {
1317 return false; // do not report participant types
1318 }
1319 if (k->is_instance_klass()) {
1320 InstanceKlass* ik = InstanceKlass::cast(k);
1321 // Search class hierarchy first, skipping private implementations
1322 // as they never override any inherited methods
1323 Method* m = ik->find_instance_method(_name, _signature, Klass::PrivateLookupMode::skip);
1324 if (Dependencies::is_concrete_method(m, ik)) {
1325 return record_witness(k, m); // concrete method found
1326 } else {
1327 // Check for re-abstraction of method
1328 if (!ik->is_interface() && m != nullptr && m->is_abstract()) {
1329 // Found a matching abstract method 'm' in the class hierarchy.
1330 // This is fine iff 'k' is an abstract class and all concrete subtypes
1331 // of 'k' override 'm' and are participates of the current search.
1332 ConcreteSubtypeFinder wf;
1333 for (uint i = 0; i < num_participants(); i++) {
1334 Klass* p = participant(i);
1335 wf.add_participant(p);
1336 }
1337 Klass* w = wf.find_witness(ik);
1338 if (w != nullptr) {
1339 Method* wm = InstanceKlass::cast(w)->find_instance_method(_name, _signature, Klass::PrivateLookupMode::skip);
1340 if (!Dependencies::is_concrete_method(wm, w)) {
1341 // Found a concrete subtype 'w' which does not override abstract method 'm'.
1342 // Bail out because 'm' could be called with 'w' as receiver (leading to an
1343 // AbstractMethodError) and thus the method we are looking for is not unique.
1344 return record_witness(k, m);
1345 }
1346 }
1347 }
1348 // Check interface defaults also, if any exist.
1349 Array<Method*>* default_methods = ik->default_methods();
1350 if (default_methods != nullptr) {
1351 Method* dm = ik->find_method(default_methods, _name, _signature);
1352 if (Dependencies::is_concrete_method(dm, nullptr)) {
1353 return record_witness(k, dm); // default method found
1354 }
1355 }
1356 return false; // no concrete method found
1357 }
1358 } else {
1359 return false; // no methods to find in an array type
1360 }
1361 }
1362
1363 Klass* ConcreteMethodFinder::find_witness_in(KlassDepChange& changes) {
1364 // When looking for unexpected concrete methods, look beneath expected ones, to see if there are overrides.
1365 // * CX.m > CC.m > C'.m is not OK, if C'.m is new, and C' is the witness.
1366 Klass* new_type = changes.as_new_klass_change()->new_type();
1367 assert(!is_participant(new_type), "only old classes are participants");
1368 if (is_witness(new_type)) {
1369 return new_type;
1370 } else {
1371 // No witness found, but is_witness() doesn't detect method re-abstraction in case of spot-checking.
1372 if (witnessed_reabstraction_in_supers(new_type)) {
1373 return new_type;
1374 }
1375 }
1376 // No witness found. The dependency remains unbroken.
1377 return nullptr;
1378 }
1379
1380 bool ConcreteMethodFinder::witnessed_reabstraction_in_supers(Klass* k) {
1381 if (!k->is_instance_klass()) {
1382 return false; // no methods to find in an array type
1383 } else {
1384 // Looking for a case when an abstract method is inherited into a concrete class.
1385 if (Dependencies::is_concrete_klass(k) && !k->is_interface()) {
1386 Method* m = InstanceKlass::cast(k)->find_instance_method(_name, _signature, Klass::PrivateLookupMode::skip);
1387 if (m != nullptr) {
1388 return false; // no reabstraction possible: local method found
1389 }
1390 for (InstanceKlass* super = k->java_super(); super != nullptr; super = super->java_super()) {
1391 m = super->find_instance_method(_name, _signature, Klass::PrivateLookupMode::skip);
1392 if (m != nullptr) { // inherited method found
1393 if (m->is_abstract() || m->is_overpass()) {
1394 return record_witness(super, m); // abstract method found
1395 }
1396 return false;
1397 }
1398 }
1399 // Miranda.
1400 return true;
1401 }
1402 return false;
1403 }
1404 }
1405
1406
1407 Klass* ConcreteMethodFinder::find_witness_anywhere(InstanceKlass* context_type) {
1408 // Walk hierarchy under a context type, looking for unexpected types.
1409 for (CountingClassHierarchyIterator iter(context_type); !iter.done(); iter.next()) {
1410 Klass* sub = iter.klass();
1411 if (is_witness(sub)) {
1412 return sub; // found a witness
1413 }
1414 }
1415 // No witness found. The dependency remains unbroken.
1416 return nullptr;
1417 }
1418
1419 // For some method m and some class ctxk (subclass of method holder),
1420 // enumerate all distinct overrides of m in concrete subclasses of ctxk.
1421 // It relies on vtable/itable information to perform method selection on each linked subclass
1422 // and ignores all non yet linked ones (speculatively treat them as "effectively abstract").
1423 class LinkedConcreteMethodFinder : public AbstractClassHierarchyWalker {
1424 private:
1425 InstanceKlass* _resolved_klass; // resolved class (JVMS-5.4.3.1)
1426 InstanceKlass* _declaring_klass; // the holder of resolved method (JVMS-5.4.3.3)
1427 int _vtable_index; // vtable/itable index of the resolved method
1428 bool _do_itable_lookup; // choose between itable and vtable lookup logic
1429
1430 // cache of method lookups
1431 Method* _found_methods[PARTICIPANT_LIMIT+1];
1432
1433 bool is_witness(Klass* k);
1434 Method* select_method(InstanceKlass* recv_klass);
1435 static int compute_vtable_index(InstanceKlass* resolved_klass, Method* resolved_method, bool& is_itable_index);
1436 static bool is_concrete_klass(InstanceKlass* ik);
1437
1438 void add_participant(Method* m, Klass* participant) {
1439 uint np = num_participants();
1440 AbstractClassHierarchyWalker::add_participant(participant);
1441 assert(np + 1 == num_participants(), "sanity");
1442 _found_methods[np] = m; // record the method for the participant
1443 }
1444
1445 bool record_witness(Klass* witness, Method* m) {
1446 for (uint i = 0; i < num_participants(); i++) {
1447 if (found_method(i) == m) {
1448 return false; // already recorded
1449 }
1450 }
1451 // Record not yet seen method.
1452 _found_methods[num_participants()] = m;
1453 return AbstractClassHierarchyWalker::record_witness(witness);
1454 }
1455
1456 void initialize(Method* participant) {
1457 for (uint i = 0; i < PARTICIPANT_LIMIT+1; i++) {
1458 _found_methods[i] = nullptr;
1459 }
1460 if (participant != nullptr) {
1461 add_participant(participant, participant->method_holder());
1462 }
1463 }
1464
1465 protected:
1466 virtual Klass* find_witness_in(KlassDepChange& changes);
1467 virtual Klass* find_witness_anywhere(InstanceKlass* context_type);
1468
1469 public:
1470 // In order to perform method selection, the following info is needed:
1471 // (1) interface or virtual call;
1472 // (2) vtable/itable index;
1473 // (3) declaring class (in case of interface call).
1474 //
1475 // It is prepared based on the results of method resolution: resolved class and resolved method (as specified in JVMS-5.4.3.3).
1476 // Optionally, a method which was previously determined as a unique target (uniqm) is added as a participant
1477 // to enable dependency spot-checking and speed up the search.
1478 LinkedConcreteMethodFinder(InstanceKlass* resolved_klass, Method* resolved_method, Method* uniqm = nullptr) : AbstractClassHierarchyWalker(nullptr) {
1479 assert(UseVtableBasedCHA, "required");
1480 assert(resolved_klass->is_linked(), "required");
1481 assert(resolved_method->method_holder()->is_linked(), "required");
1482 assert(!resolved_method->can_be_statically_bound(), "no vtable index available");
1483
1484 _resolved_klass = resolved_klass;
1485 _declaring_klass = resolved_method->method_holder();
1486 _vtable_index = compute_vtable_index(resolved_klass, resolved_method,
1487 _do_itable_lookup); // out parameter
1488 assert(_vtable_index >= 0, "invalid vtable index");
1489
1490 initialize(uniqm);
1491 }
1492
1493 // Note: If n==num_participants, returns nullptr.
1494 Method* found_method(uint n) {
1495 assert(n <= num_participants(), "oob");
1496 assert(participant(n) != nullptr || n == num_participants(), "proper usage");
1497 return _found_methods[n];
1498 }
1499 };
1500
1501 Klass* LinkedConcreteMethodFinder::find_witness_in(KlassDepChange& changes) {
1502 Klass* type = changes.type();
1503
1504 assert(!is_participant(type), "only old classes are participants");
1505
1506 if (is_witness(type)) {
1507 return type;
1508 }
1509 return nullptr; // No witness found. The dependency remains unbroken.
1510 }
1511
1512 Klass* LinkedConcreteMethodFinder::find_witness_anywhere(InstanceKlass* context_type) {
1513 for (CountingClassHierarchyIterator iter(context_type); !iter.done(); iter.next()) {
1514 Klass* sub = iter.klass();
1515 if (is_witness(sub)) {
1516 return sub;
1517 }
1518 if (sub->is_instance_klass() && !InstanceKlass::cast(sub)->is_linked()) {
1519 iter.skip_subclasses(); // ignore not yet linked classes
1520 }
1521 }
1522 return nullptr; // No witness found. The dependency remains unbroken.
1523 }
1524
1525 bool LinkedConcreteMethodFinder::is_witness(Klass* k) {
1526 if (is_participant(k)) {
1527 return false; // do not report participant types
1528 } else if (k->is_instance_klass()) {
1529 InstanceKlass* ik = InstanceKlass::cast(k);
1530 if (is_concrete_klass(ik)) {
1531 Method* m = select_method(ik);
1532 return record_witness(ik, m);
1533 } else {
1534 return false; // ignore non-concrete holder class
1535 }
1536 } else {
1537 return false; // no methods to find in an array type
1538 }
1539 }
1540
1541 Method* LinkedConcreteMethodFinder::select_method(InstanceKlass* recv_klass) {
1542 Method* selected_method = nullptr;
1543 if (_do_itable_lookup) {
1544 assert(_declaring_klass->is_interface(), "sanity");
1545 bool implements_interface; // initialized by method_at_itable_or_null()
1546 selected_method = recv_klass->method_at_itable_or_null(_declaring_klass, _vtable_index,
1547 implements_interface); // out parameter
1548 assert(implements_interface, "not implemented");
1549 } else {
1550 selected_method = recv_klass->method_at_vtable(_vtable_index);
1551 }
1552 return selected_method; // nullptr when corresponding slot is empty (AbstractMethodError case)
1553 }
1554
1555 int LinkedConcreteMethodFinder::compute_vtable_index(InstanceKlass* resolved_klass, Method* resolved_method,
1556 // out parameter
1557 bool& is_itable_index) {
1558 if (resolved_klass->is_interface() && resolved_method->has_itable_index()) {
1559 is_itable_index = true;
1560 return resolved_method->itable_index();
1561 }
1562 // Check for default or miranda method first.
1563 InstanceKlass* declaring_klass = resolved_method->method_holder();
1564 if (!resolved_klass->is_interface() && declaring_klass->is_interface()) {
1565 is_itable_index = false;
1566 return resolved_klass->vtable_index_of_interface_method(resolved_method);
1567 }
1568 // At this point we are sure that resolved_method is virtual and not
1569 // a default or miranda method; therefore, it must have a valid vtable index.
1570 assert(resolved_method->has_vtable_index(), "");
1571 is_itable_index = false;
1572 return resolved_method->vtable_index();
1573 }
1574
1575 bool LinkedConcreteMethodFinder::is_concrete_klass(InstanceKlass* ik) {
1576 if (!Dependencies::is_concrete_klass(ik)) {
1577 return false; // not concrete
1578 }
1579 if (ik->is_interface()) {
1580 return false; // interfaces aren't concrete
1581 }
1582 if (!ik->is_linked()) {
1583 return false; // not yet linked classes don't have instances
1584 }
1585 return true;
1586 }
1587
1588 #ifdef ASSERT
1589 // Assert that m is inherited into ctxk, without intervening overrides.
1590 // (May return true even if this is not true, in corner cases where we punt.)
1591 bool Dependencies::verify_method_context(InstanceKlass* ctxk, Method* m) {
1592 if (m->is_private()) {
1593 return false; // Quick lose. Should not happen.
1594 }
1595 if (m->method_holder() == ctxk) {
1596 return true; // Quick win.
1597 }
1598 if (!(m->is_public() || m->is_protected())) {
1599 // The override story is complex when packages get involved.
1600 return true; // Must punt the assertion to true.
1601 }
1602 Method* lm = ctxk->lookup_method(m->name(), m->signature());
1603 if (lm == nullptr) {
1604 // It might be an interface method
1605 lm = ctxk->lookup_method_in_ordered_interfaces(m->name(), m->signature());
1606 }
1607 if (lm == m) {
1608 // Method m is inherited into ctxk.
1609 return true;
1610 }
1611 if (lm != nullptr) {
1612 if (!(lm->is_public() || lm->is_protected())) {
1613 // Method is [package-]private, so the override story is complex.
1614 return true; // Must punt the assertion to true.
1615 }
1616 if (lm->is_static()) {
1617 // Static methods don't override non-static so punt
1618 return true;
1619 }
1620 if (!Dependencies::is_concrete_method(lm, ctxk) &&
1621 !Dependencies::is_concrete_method(m, ctxk)) {
1622 // They are both non-concrete
1623 if (lm->method_holder()->is_subtype_of(m->method_holder())) {
1624 // Method m is overridden by lm, but both are non-concrete.
1625 return true;
1626 }
1627 if (lm->method_holder()->is_interface() && m->method_holder()->is_interface() &&
1628 ctxk->is_subtype_of(m->method_holder()) && ctxk->is_subtype_of(lm->method_holder())) {
1629 // Interface method defined in multiple super interfaces
1630 return true;
1631 }
1632 }
1633 }
1634 ResourceMark rm;
1635 tty->print_cr("Dependency method not found in the associated context:");
1636 tty->print_cr(" context = %s", ctxk->external_name());
1637 tty->print( " method = "); m->print_short_name(tty); tty->cr();
1638 if (lm != nullptr) {
1639 tty->print( " found = "); lm->print_short_name(tty); tty->cr();
1640 }
1641 return false;
1642 }
1643 #endif // ASSERT
1644
1645 bool Dependencies::is_concrete_klass(Klass* k) {
1646 if (k->is_abstract()) return false;
1647 // %%% We could treat classes which are concrete but
1648 // have not yet been instantiated as virtually abstract.
1649 // This would require a deoptimization barrier on first instantiation.
1650 //if (k->is_not_instantiated()) return false;
1651 return true;
1652 }
1653
1654 bool Dependencies::is_concrete_method(Method* m, Klass* k) {
1655 // nullptr is not a concrete method.
1656 if (m == nullptr) {
1657 return false;
1658 }
1659 // Statics are irrelevant to virtual call sites.
1660 if (m->is_static()) {
1661 return false;
1662 }
1663 // Abstract methods are not concrete.
1664 if (m->is_abstract()) {
1665 return false;
1666 }
1667 // Overpass (error) methods are not concrete if k is abstract.
1668 if (m->is_overpass() && k != nullptr) {
1669 return !k->is_abstract();
1670 }
1671 // Note "true" is conservative answer: overpass clause is false if k == nullptr,
1672 // implies return true if answer depends on overpass clause.
1673 return true;
1674 }
1675
1676 Klass* Dependencies::find_finalizable_subclass(InstanceKlass* ik) {
1677 for (ClassHierarchyIterator iter(ik); !iter.done(); iter.next()) {
1678 Klass* sub = iter.klass();
1679 if (sub->has_finalizer() && !sub->is_interface()) {
1680 return sub;
1681 }
1682 }
1683 return nullptr; // not found
1684 }
1685
1686 bool Dependencies::is_concrete_klass(ciInstanceKlass* k) {
1687 if (k->is_abstract()) return false;
1688 // We could also return false if k does not yet appear to be
1689 // instantiated, if the VM version supports this distinction also.
1690 //if (k->is_not_instantiated()) return false;
1691 return true;
1692 }
1693
1694 bool Dependencies::has_finalizable_subclass(ciInstanceKlass* k) {
1695 return k->has_finalizable_subclass();
1696 }
1697
1698 // Any use of the contents (bytecodes) of a method must be
1699 // marked by an "evol_method" dependency, if those contents
1700 // can change. (Note: A method is always dependent on itself.)
1701 Klass* Dependencies::check_evol_method(Method* m) {
1702 assert(must_be_in_vm(), "raw oops here");
1703 // Did somebody do a JVMTI RedefineClasses while our backs were turned?
1704 // Or is there a now a breakpoint?
1705 // (Assumes compiled code cannot handle bkpts; change if UseFastBreakpoints.)
1706 if (m->is_old()
1707 || m->number_of_breakpoints() > 0
1708 || m->mismatch()) {
1709 return m->method_holder();
1710 } else {
1711 return nullptr;
1712 }
1713 }
1714
1715 // This is a strong assertion: It is that the given type
1716 // has no subtypes whatever. It is most useful for
1717 // optimizing checks on reflected types or on array types.
1718 // (Checks on types which are derived from real instances
1719 // can be optimized more strongly than this, because we
1720 // know that the checked type comes from a concrete type,
1721 // and therefore we can disregard abstract types.)
1722 Klass* Dependencies::check_leaf_type(InstanceKlass* ctxk) {
1723 assert(must_be_in_vm(), "raw oops here");
1724 assert_locked_or_safepoint(Compile_lock);
1725 Klass* sub = ctxk->subklass();
1726 if (sub != nullptr) {
1727 return sub;
1728 } else if (ctxk->nof_implementors() != 0) {
1729 // if it is an interface, it must be unimplemented
1730 // (if it is not an interface, nof_implementors is always zero)
1731 InstanceKlass* impl = ctxk->implementor();
1732 assert(impl != nullptr, "must be set");
1733 return impl;
1734 } else {
1735 return nullptr;
1736 }
1737 }
1738
1739 // Test the assertion that conck is the only concrete subtype* of ctxk.
1740 // The type conck itself is allowed to have have further concrete subtypes.
1741 // This allows the compiler to narrow occurrences of ctxk by conck,
1742 // when dealing with the types of actual instances.
1743 Klass* Dependencies::check_abstract_with_unique_concrete_subtype(InstanceKlass* ctxk,
1744 Klass* conck,
1745 NewKlassDepChange* changes) {
1746 ConcreteSubtypeFinder wf(conck);
1747 Klass* k = wf.find_witness(ctxk, changes);
1748 return k;
1749 }
1750
1751
1752 // Find the unique concrete proper subtype of ctxk, or nullptr if there
1753 // is more than one concrete proper subtype. If there are no concrete
1754 // proper subtypes, return ctxk itself, whether it is concrete or not.
1755 // The returned subtype is allowed to have have further concrete subtypes.
1756 // That is, return CC1 for CX > CC1 > CC2, but nullptr for CX > { CC1, CC2 }.
1757 Klass* Dependencies::find_unique_concrete_subtype(InstanceKlass* ctxk) {
1758 ConcreteSubtypeFinder wf(ctxk); // Ignore ctxk when walking.
1759 wf.record_witnesses(1); // Record one other witness when walking.
1760 Klass* wit = wf.find_witness(ctxk);
1761 if (wit != nullptr) return nullptr; // Too many witnesses.
1762 Klass* conck = wf.participant(0);
1763 if (conck == nullptr) {
1764 return ctxk; // Return ctxk as a flag for "no subtypes".
1765 } else {
1766 #ifndef PRODUCT
1767 // Make sure the dependency mechanism will pass this discovery:
1768 if (VerifyDependencies) {
1769 // Turn off dependency tracing while actually testing deps.
1770 FlagSetting fs(_verify_in_progress, true);
1771 if (!Dependencies::is_concrete_klass(ctxk)) {
1772 guarantee(nullptr == (void *)
1773 check_abstract_with_unique_concrete_subtype(ctxk, conck),
1774 "verify dep.");
1775 }
1776 }
1777 #endif //PRODUCT
1778 return conck;
1779 }
1780 }
1781
1782 // Try to determine whether root method in some context is concrete or not based on the information about the unique method
1783 // in that context. It exploits the fact that concrete root method is always inherited into the context when there's a unique method.
1784 // Hence, unique method holder is always a supertype of the context class when root method is concrete.
1785 // Examples for concrete_root_method
1786 // C (C.m uniqm)
1787 // |
1788 // CX (ctxk) uniqm is inherited into context.
1789 //
1790 // CX (ctxk) (CX.m uniqm) here uniqm is defined in ctxk.
1791 // Examples for !concrete_root_method
1792 // CX (ctxk)
1793 // |
1794 // C (C.m uniqm) uniqm is in subtype of ctxk.
1795 bool Dependencies::is_concrete_root_method(Method* uniqm, InstanceKlass* ctxk) {
1796 if (uniqm == nullptr) {
1797 return false; // match Dependencies::is_concrete_method() behavior
1798 }
1799 // Theoretically, the "direction" of subtype check matters here.
1800 // On one hand, in case of interface context with a single implementor, uniqm can be in a superclass of the implementor which
1801 // is not related to context class.
1802 // On another hand, uniqm could come from an interface unrelated to the context class, but right now it is not possible:
1803 // it is required that uniqm->method_holder() is the participant (uniqm->method_holder() <: ctxk), hence a default method
1804 // can't be used as unique.
1805 if (ctxk->is_interface()) {
1806 InstanceKlass* implementor = ctxk->implementor();
1807 assert(implementor != ctxk, "single implementor only"); // should have been invalidated earlier
1808 ctxk = implementor;
1809 }
1810 InstanceKlass* holder = uniqm->method_holder();
1811 assert(!holder->is_interface(), "no default methods allowed");
1812 assert(ctxk->is_subclass_of(holder) || holder->is_subclass_of(ctxk), "not related");
1813 return ctxk->is_subclass_of(holder);
1814 }
1815
1816 // If a class (or interface) has a unique concrete method uniqm, return nullptr.
1817 // Otherwise, return a class that contains an interfering method.
1818 Klass* Dependencies::check_unique_concrete_method(InstanceKlass* ctxk,
1819 Method* uniqm,
1820 NewKlassDepChange* changes) {
1821 ConcreteMethodFinder wf(uniqm, uniqm->method_holder());
1822 Klass* k = wf.find_witness(ctxk, changes);
1823 if (k != nullptr) {
1824 return k;
1825 }
1826 if (!Dependencies::is_concrete_root_method(uniqm, ctxk) || changes != nullptr) {
1827 Klass* conck = find_witness_AME(ctxk, uniqm, changes);
1828 if (conck != nullptr) {
1829 // Found a concrete subtype 'conck' which does not override abstract root method.
1830 return conck;
1831 }
1832 }
1833 return nullptr;
1834 }
1835
1836 Klass* Dependencies::check_unique_implementor(InstanceKlass* ctxk, Klass* uniqk, NewKlassDepChange* changes) {
1837 assert(ctxk->is_interface(), "sanity");
1838 assert(ctxk->nof_implementors() > 0, "no implementors");
1839 if (ctxk->nof_implementors() == 1) {
1840 assert(ctxk->implementor() == uniqk, "sanity");
1841 return nullptr;
1842 }
1843 return ctxk; // no unique implementor
1844 }
1845
1846 // Search for AME.
1847 // There are two version of checks.
1848 // 1) Spot checking version(Classload time). Newly added class is checked for AME.
1849 // Checks whether abstract/overpass method is inherited into/declared in newly added concrete class.
1850 // 2) Compile time analysis for abstract/overpass(abstract klass) root_m. The non uniqm subtrees are checked for concrete classes.
1851 Klass* Dependencies::find_witness_AME(InstanceKlass* ctxk, Method* m, KlassDepChange* changes) {
1852 if (m != nullptr) {
1853 if (changes != nullptr) {
1854 // Spot checking version.
1855 ConcreteMethodFinder wf(m);
1856 Klass* new_type = changes->as_new_klass_change()->new_type();
1857 if (wf.witnessed_reabstraction_in_supers(new_type)) {
1858 return new_type;
1859 }
1860 } else {
1861 // Note: It is required that uniqm->method_holder() is the participant (see ClassHierarchyWalker::found_method()).
1862 ConcreteSubtypeFinder wf(m->method_holder());
1863 Klass* conck = wf.find_witness(ctxk);
1864 if (conck != nullptr) {
1865 Method* cm = InstanceKlass::cast(conck)->find_instance_method(m->name(), m->signature(), Klass::PrivateLookupMode::skip);
1866 if (!Dependencies::is_concrete_method(cm, conck)) {
1867 return conck;
1868 }
1869 }
1870 }
1871 }
1872 return nullptr;
1873 }
1874
1875 // This function is used by find_unique_concrete_method(non vtable based)
1876 // to check whether subtype method overrides the base method.
1877 static bool overrides(Method* sub_m, Method* base_m) {
1878 assert(base_m != nullptr, "base method should be non null");
1879 if (sub_m == nullptr) {
1880 return false;
1881 }
1882 /**
1883 * If base_m is public or protected then sub_m always overrides.
1884 * If base_m is !public, !protected and !private (i.e. base_m is package private)
1885 * then sub_m should be in the same package as that of base_m.
1886 * For package private base_m this is conservative approach as it allows only subset of all allowed cases in
1887 * the jvm specification.
1888 **/
1889 if (base_m->is_public() || base_m->is_protected() ||
1890 base_m->method_holder()->is_same_class_package(sub_m->method_holder())) {
1891 return true;
1892 }
1893 return false;
1894 }
1895
1896 // Find the set of all non-abstract methods under ctxk that match m.
1897 // (The method m must be defined or inherited in ctxk.)
1898 // Include m itself in the set, unless it is abstract.
1899 // If this set has exactly one element, return that element.
1900 Method* Dependencies::find_unique_concrete_method(InstanceKlass* ctxk, Method* m, Klass** participant) {
1901 // Return nullptr if m is marked old; must have been a redefined method.
1902 if (m->is_old()) {
1903 return nullptr;
1904 }
1905 if (m->is_default_method()) {
1906 return nullptr; // not supported
1907 }
1908 assert(verify_method_context(ctxk, m), "proper context");
1909 ConcreteMethodFinder wf(m);
1910 wf.record_witnesses(1);
1911 Klass* wit = wf.find_witness(ctxk);
1912 if (wit != nullptr) return nullptr; // Too many witnesses.
1913 Method* fm = wf.found_method(0); // Will be nullptr if num_parts == 0.
1914 if (participant != nullptr) {
1915 (*participant) = wf.participant(0);
1916 }
1917 if (!Dependencies::is_concrete_method(fm, nullptr)) {
1918 fm = nullptr; // ignore abstract methods
1919 }
1920 if (Dependencies::is_concrete_method(m, ctxk)) {
1921 if (fm == nullptr) {
1922 // It turns out that m was always the only implementation.
1923 fm = m;
1924 } else if (fm != m) {
1925 // Two conflicting implementations after all.
1926 // (This can happen if m is inherited into ctxk and fm overrides it.)
1927 return nullptr;
1928 }
1929 } else if (Dependencies::find_witness_AME(ctxk, fm) != nullptr) {
1930 // Found a concrete subtype which does not override abstract root method.
1931 return nullptr;
1932 } else if (!overrides(fm, m)) {
1933 // Found method doesn't override abstract root method.
1934 return nullptr;
1935 }
1936 assert(Dependencies::is_concrete_root_method(fm, ctxk) == Dependencies::is_concrete_method(m, ctxk), "mismatch");
1937 #ifndef PRODUCT
1938 // Make sure the dependency mechanism will pass this discovery:
1939 if (VerifyDependencies && fm != nullptr) {
1940 guarantee(nullptr == (void *)check_unique_concrete_method(ctxk, fm),
1941 "verify dep.");
1942 }
1943 #endif //PRODUCT
1944 return fm;
1945 }
1946
1947 // If a class (or interface) has a unique concrete method uniqm, return nullptr.
1948 // Otherwise, return a class that contains an interfering method.
1949 Klass* Dependencies::check_unique_concrete_method(InstanceKlass* ctxk,
1950 Method* uniqm,
1951 Klass* resolved_klass,
1952 Method* resolved_method,
1953 KlassDepChange* changes) {
1954 assert(UseVtableBasedCHA, "required");
1955 assert(!ctxk->is_interface() || ctxk == resolved_klass, "sanity");
1956 assert(!resolved_method->can_be_statically_bound() || resolved_method == uniqm, "sanity");
1957 assert(resolved_klass->is_subtype_of(resolved_method->method_holder()), "sanity");
1958
1959 if (!InstanceKlass::cast(resolved_klass)->is_linked() ||
1960 !resolved_method->method_holder()->is_linked() ||
1961 resolved_method->can_be_statically_bound()) {
1962 // Dependency is redundant, but benign. Just keep it to avoid unnecessary recompilation.
1963 return nullptr; // no vtable index available
1964 }
1965
1966 LinkedConcreteMethodFinder mf(InstanceKlass::cast(resolved_klass), resolved_method, uniqm);
1967 return mf.find_witness(ctxk, changes);
1968 }
1969
1970 // Find the set of all non-abstract methods under ctxk that match m.
1971 // (The method m must be defined or inherited in ctxk.)
1972 // Include m itself in the set, unless it is abstract.
1973 // If this set has exactly one element, return that element.
1974 // Not yet linked subclasses of ctxk are ignored since they don't have any instances yet.
1975 // Additionally, resolved_klass and resolved_method complete the description of the call site being analyzed.
1976 Method* Dependencies::find_unique_concrete_method(InstanceKlass* ctxk, Method* m, Klass* resolved_klass, Method* resolved_method) {
1977 // Return nullptr if m is marked old; must have been a redefined method.
1978 if (m->is_old()) {
1979 return nullptr;
1980 }
1981 if (!InstanceKlass::cast(resolved_klass)->is_linked() ||
1982 !resolved_method->method_holder()->is_linked() ||
1983 resolved_method->can_be_statically_bound()) {
1984 return m; // nothing to do: no witness under ctxk
1985 }
1986 LinkedConcreteMethodFinder wf(InstanceKlass::cast(resolved_klass), resolved_method);
1987 assert(Dependencies::verify_method_context(ctxk, m), "proper context");
1988 wf.record_witnesses(1);
1989 Klass* wit = wf.find_witness(ctxk);
1990 if (wit != nullptr) {
1991 return nullptr; // Too many witnesses.
1992 }
1993 // p == nullptr when no participants are found (wf.num_participants() == 0).
1994 // fm == nullptr case has 2 meanings:
1995 // * when p == nullptr: no method found;
1996 // * when p != nullptr: AbstractMethodError-throwing method found.
1997 // Also, found method should always be accompanied by a participant class.
1998 Klass* p = wf.participant(0);
1999 Method* fm = wf.found_method(0);
2000 assert(fm == nullptr || p != nullptr, "no participant");
2001 // Normalize all error-throwing cases to nullptr.
2002 if (fm == Universe::throw_illegal_access_error() ||
2003 fm == Universe::throw_no_such_method_error() ||
2004 !Dependencies::is_concrete_method(fm, p)) {
2005 fm = nullptr; // error-throwing method
2006 }
2007 if (Dependencies::is_concrete_method(m, ctxk)) {
2008 if (p == nullptr) {
2009 // It turns out that m was always the only implementation.
2010 assert(fm == nullptr, "sanity");
2011 fm = m;
2012 }
2013 }
2014 #ifndef PRODUCT
2015 // Make sure the dependency mechanism will pass this discovery:
2016 if (VerifyDependencies && fm != nullptr) {
2017 guarantee(nullptr == check_unique_concrete_method(ctxk, fm, resolved_klass, resolved_method),
2018 "verify dep.");
2019 }
2020 #endif // PRODUCT
2021 assert(fm == nullptr || !fm->is_abstract(), "sanity");
2022 // Old CHA conservatively reports concrete methods in abstract classes
2023 // irrespective of whether they have concrete subclasses or not.
2024 // Also, abstract root method case is not fully supported.
2025 #ifdef ASSERT
2026 Klass* uniqp = nullptr;
2027 Method* uniqm = Dependencies::find_unique_concrete_method(ctxk, m, &uniqp);
2028 assert(uniqm == nullptr || uniqm == fm ||
2029 m->is_abstract() ||
2030 uniqm->method_holder()->is_abstract() ||
2031 (fm == nullptr && uniqm != nullptr && uniqp != nullptr && !InstanceKlass::cast(uniqp)->is_linked()),
2032 "sanity");
2033 #endif // ASSERT
2034 return fm;
2035 }
2036
2037 Klass* Dependencies::check_has_no_finalizable_subclasses(InstanceKlass* ctxk, NewKlassDepChange* changes) {
2038 InstanceKlass* search_at = ctxk;
2039 if (changes != nullptr) {
2040 search_at = changes->new_type(); // just look at the new bit
2041 }
2042 return find_finalizable_subclass(search_at);
2043 }
2044
2045 Klass* Dependencies::check_call_site_target_value(oop call_site, oop method_handle, CallSiteDepChange* changes) {
2046 assert(call_site != nullptr, "sanity");
2047 assert(method_handle != nullptr, "sanity");
2048 assert(call_site->is_a(vmClasses::CallSite_klass()), "sanity");
2049
2050 if (changes == nullptr) {
2051 // Validate all CallSites
2052 if (java_lang_invoke_CallSite::target(call_site) != method_handle)
2053 return call_site->klass(); // assertion failed
2054 } else {
2055 // Validate the given CallSite
2056 if (call_site == changes->call_site() && java_lang_invoke_CallSite::target(call_site) != changes->method_handle()) {
2057 assert(method_handle != changes->method_handle(), "must be");
2058 return call_site->klass(); // assertion failed
2059 }
2060 }
2061 return nullptr; // assertion still valid
2062 }
2063
2064 void Dependencies::DepStream::trace_and_log_witness(Klass* witness) {
2065 if (_verify_in_progress) return; // don't log
2066 if (witness != nullptr) {
2067 LogTarget(Debug, dependencies) lt;
2068 if (lt.is_enabled()) {
2069 LogStream ls(<);
2070 print_dependency(&ls, witness, /*verbose=*/ true);
2071 }
2072 // The following is a no-op unless logging is enabled:
2073 log_dependency(witness);
2074 }
2075 }
2076
2077 Klass* Dependencies::DepStream::check_new_klass_dependency(NewKlassDepChange* changes) {
2078 assert_locked_or_safepoint(Compile_lock);
2079 Dependencies::check_valid_dependency_type(type());
2080
2081 Klass* witness = nullptr;
2082 switch (type()) {
2083 case evol_method:
2084 witness = check_evol_method(method_argument(0));
2085 break;
2086 case leaf_type:
2087 witness = check_leaf_type(context_type());
2088 break;
2089 case abstract_with_unique_concrete_subtype:
2090 witness = check_abstract_with_unique_concrete_subtype(context_type(), type_argument(1), changes);
2091 break;
2092 case unique_concrete_method_2:
2093 witness = check_unique_concrete_method(context_type(), method_argument(1), changes);
2094 break;
2095 case unique_concrete_method_4:
2096 witness = check_unique_concrete_method(context_type(), method_argument(1), type_argument(2), method_argument(3), changes);
2097 break;
2098 case unique_implementor:
2099 witness = check_unique_implementor(context_type(), type_argument(1), changes);
2100 break;
2101 case no_finalizable_subclasses:
2102 witness = check_has_no_finalizable_subclasses(context_type(), changes);
2103 break;
2104 default:
2105 witness = nullptr;
2106 break;
2107 }
2108 trace_and_log_witness(witness);
2109 return witness;
2110 }
2111
2112 Klass* Dependencies::DepStream::check_klass_init_dependency(KlassInitDepChange* changes) {
2113 assert_locked_or_safepoint(Compile_lock);
2114 Dependencies::check_valid_dependency_type(type());
2115
2116 // No new types added. Only unique_concrete_method_4 is sensitive to class initialization changes.
2117 Klass* witness = nullptr;
2118 switch (type()) {
2119 case unique_concrete_method_4:
2120 witness = check_unique_concrete_method(context_type(), method_argument(1), type_argument(2), method_argument(3), changes);
2121 break;
2122 default:
2123 witness = nullptr;
2124 break;
2125 }
2126 trace_and_log_witness(witness);
2127 return witness;
2128 }
2129
2130 Klass* Dependencies::DepStream::check_klass_dependency(KlassDepChange* changes) {
2131 assert_locked_or_safepoint(Compile_lock);
2132 Dependencies::check_valid_dependency_type(type());
2133
2134 if (changes != nullptr) {
2135 if (UseVtableBasedCHA && changes->is_klass_init_change()) {
2136 return check_klass_init_dependency(changes->as_klass_init_change());
2137 } else {
2138 return check_new_klass_dependency(changes->as_new_klass_change());
2139 }
2140 } else {
2141 Klass* witness = check_new_klass_dependency(nullptr);
2142 // check_klass_init_dependency duplicates check_new_klass_dependency checks when class hierarchy change info is absent.
2143 assert(witness != nullptr || check_klass_init_dependency(nullptr) == nullptr, "missed dependency");
2144 return witness;
2145 }
2146 }
2147
2148 Klass* Dependencies::DepStream::check_call_site_dependency(CallSiteDepChange* changes) {
2149 assert_locked_or_safepoint(Compile_lock);
2150 Dependencies::check_valid_dependency_type(type());
2151
2152 Klass* witness = nullptr;
2153 switch (type()) {
2154 case call_site_target_value:
2155 witness = check_call_site_target_value(argument_oop(0), argument_oop(1), changes);
2156 break;
2157 default:
2158 witness = nullptr;
2159 break;
2160 }
2161 trace_and_log_witness(witness);
2162 return witness;
2163 }
2164
2165
2166 Klass* Dependencies::DepStream::spot_check_dependency_at(DepChange& changes) {
2167 // Handle klass dependency
2168 if (changes.is_klass_change() && changes.as_klass_change()->involves_context(context_type()))
2169 return check_klass_dependency(changes.as_klass_change());
2170
2171 // Handle CallSite dependency
2172 if (changes.is_call_site_change())
2173 return check_call_site_dependency(changes.as_call_site_change());
2174
2175 // irrelevant dependency; skip it
2176 return nullptr;
2177 }
2178
2179
2180 void DepChange::print() { print_on(tty); }
2181
2182 void DepChange::print_on(outputStream* st) {
2183 int nsup = 0, nint = 0;
2184 for (ContextStream str(*this); str.next(); ) {
2185 InstanceKlass* k = str.klass();
2186 switch (str.change_type()) {
2187 case Change_new_type:
2188 st->print_cr(" dependee = %s", k->external_name());
2189 break;
2190 case Change_new_sub:
2191 if (!WizardMode) {
2192 ++nsup;
2193 } else {
2194 st->print_cr(" context super = %s", k->external_name());
2195 }
2196 break;
2197 case Change_new_impl:
2198 if (!WizardMode) {
2199 ++nint;
2200 } else {
2201 st->print_cr(" context interface = %s", k->external_name());
2202 }
2203 break;
2204 default:
2205 break;
2206 }
2207 }
2208 if (nsup + nint != 0) {
2209 st->print_cr(" context supers = %d, interfaces = %d", nsup, nint);
2210 }
2211 }
2212
2213 void DepChange::ContextStream::start() {
2214 InstanceKlass* type = (_changes.is_klass_change() ? _changes.as_klass_change()->type() : (InstanceKlass*) nullptr);
2215 _change_type = (type == nullptr ? NO_CHANGE : Start_Klass);
2216 _klass = type;
2217 _ti_base = nullptr;
2218 _ti_index = 0;
2219 _ti_limit = 0;
2220 }
2221
2222 bool DepChange::ContextStream::next() {
2223 switch (_change_type) {
2224 case Start_Klass: // initial state; _klass is the new type
2225 _ti_base = _klass->transitive_interfaces();
2226 _ti_index = 0;
2227 _change_type = Change_new_type;
2228 return true;
2229 case Change_new_type:
2230 // fall through:
2231 _change_type = Change_new_sub;
2232 case Change_new_sub:
2233 // 6598190: brackets workaround Sun Studio C++ compiler bug 6629277
2234 {
2235 _klass = _klass->java_super();
2236 if (_klass != nullptr) {
2237 return true;
2238 }
2239 }
2240 // else set up _ti_limit and fall through:
2241 _ti_limit = (_ti_base == nullptr) ? 0 : _ti_base->length();
2242 _change_type = Change_new_impl;
2243 case Change_new_impl:
2244 if (_ti_index < _ti_limit) {
2245 _klass = _ti_base->at(_ti_index++);
2246 return true;
2247 }
2248 // fall through:
2249 _change_type = NO_CHANGE; // iterator is exhausted
2250 case NO_CHANGE:
2251 break;
2252 default:
2253 ShouldNotReachHere();
2254 }
2255 return false;
2256 }
2257
2258 void KlassDepChange::initialize() {
2259 // entire transaction must be under this lock:
2260 assert_lock_strong(Compile_lock);
2261
2262 // Mark all dependee and all its superclasses
2263 // Mark transitive interfaces
2264 for (ContextStream str(*this); str.next(); ) {
2265 InstanceKlass* d = str.klass();
2266 assert(!d->is_marked_dependent(), "checking");
2267 d->set_is_marked_dependent(true);
2268 }
2269 }
2270
2271 KlassDepChange::~KlassDepChange() {
2272 // Unmark all dependee and all its superclasses
2273 // Unmark transitive interfaces
2274 for (ContextStream str(*this); str.next(); ) {
2275 InstanceKlass* d = str.klass();
2276 d->set_is_marked_dependent(false);
2277 }
2278 }
2279
2280 bool KlassDepChange::involves_context(Klass* k) {
2281 if (k == nullptr || !k->is_instance_klass()) {
2282 return false;
2283 }
2284 InstanceKlass* ik = InstanceKlass::cast(k);
2285 bool is_contained = ik->is_marked_dependent();
2286 assert(is_contained == type()->is_subtype_of(k),
2287 "correct marking of potential context types");
2288 return is_contained;
2289 }
2290
2291 void Dependencies::print_statistics() {
2292 AbstractClassHierarchyWalker::print_statistics();
2293 }
2294
2295 void AbstractClassHierarchyWalker::print_statistics() {
2296 if (UsePerfData) {
2297 jlong deps_find_witness_calls = _perf_find_witness_anywhere_calls_count->get_value();
2298 jlong deps_find_witness_steps = _perf_find_witness_anywhere_steps_count->get_value();
2299 jlong deps_find_witness_singles = _perf_find_witness_in_calls_count->get_value();
2300
2301 ttyLocker ttyl;
2302 tty->print_cr("Dependency check (find_witness) "
2303 "calls=" JLONG_FORMAT ", steps=" JLONG_FORMAT " (avg=%.1f), singles=" JLONG_FORMAT,
2304 deps_find_witness_calls,
2305 deps_find_witness_steps,
2306 (double)deps_find_witness_steps / deps_find_witness_calls,
2307 deps_find_witness_singles);
2308 if (xtty != nullptr) {
2309 xtty->elem("deps_find_witness calls='" JLONG_FORMAT "' steps='" JLONG_FORMAT "' singles='" JLONG_FORMAT "'",
2310 deps_find_witness_calls,
2311 deps_find_witness_steps,
2312 deps_find_witness_singles);
2313 }
2314 }
2315 }
2316
2317 CallSiteDepChange::CallSiteDepChange(Handle call_site, Handle method_handle) :
2318 _call_site(call_site),
2319 _method_handle(method_handle) {
2320 assert(_call_site()->is_a(vmClasses::CallSite_klass()), "must be");
2321 assert(_method_handle.is_null() || _method_handle()->is_a(vmClasses::MethodHandle_klass()), "must be");
2322 }
2323
2324 void dependencies_init() {
2325 AbstractClassHierarchyWalker::init();
2326 }