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