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