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