1 /*
2 * Copyright (c) 2017, 2025, Red Hat, Inc. All rights reserved.
3 * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
4 * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
5 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
6 *
7 * This code is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License version 2 only, as
9 * published by the Free Software Foundation.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 *
25 */
26
27 #include "gc/shared/tlab_globals.hpp"
28 #include "gc/shenandoah/shenandoahAsserts.hpp"
29 #include "gc/shenandoah/shenandoahForwarding.inline.hpp"
30 #include "gc/shenandoah/shenandoahGeneration.hpp"
31 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
32 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
33 #include "gc/shenandoah/shenandoahOldGeneration.hpp"
34 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
35 #include "gc/shenandoah/shenandoahRootProcessor.hpp"
36 #include "gc/shenandoah/shenandoahScanRemembered.inline.hpp"
37 #include "gc/shenandoah/shenandoahTaskqueue.inline.hpp"
38 #include "gc/shenandoah/shenandoahUtils.hpp"
39 #include "gc/shenandoah/shenandoahVerifier.hpp"
40 #include "gc/shenandoah/shenandoahYoungGeneration.hpp"
41 #include "memory/allocation.hpp"
42 #include "memory/iterator.inline.hpp"
43 #include "memory/resourceArea.hpp"
44 #include "oops/compressedOops.inline.hpp"
45 #include "runtime/atomic.hpp"
46 #include "runtime/orderAccess.hpp"
47 #include "runtime/threads.hpp"
48 #include "utilities/align.hpp"
49
50 // Avoid name collision on verify_oop (defined in macroAssembler_arm.hpp)
51 #ifdef verify_oop
52 #undef verify_oop
53 #endif
54
55 static bool is_instance_ref_klass(Klass* k) {
56 return k->is_instance_klass() && InstanceKlass::cast(k)->reference_type() != REF_NONE;
57 }
58
59 class ShenandoahVerifyOopClosure : public BasicOopIterateClosure {
60 private:
61 const char* _phase;
62 ShenandoahVerifier::VerifyOptions _options;
63 ShenandoahVerifierStack* _stack;
64 ShenandoahHeap* _heap;
65 MarkBitMap* _map;
66 ShenandoahLivenessData* _ld;
67 void* _interior_loc;
68 oop _loc;
69 ReferenceIterationMode _ref_mode;
70 ShenandoahGeneration* _generation;
71
72 public:
73 ShenandoahVerifyOopClosure(ShenandoahGeneration* generation, ShenandoahVerifierStack* stack,
74 MarkBitMap* map, ShenandoahLivenessData* ld,
75 const char* phase, ShenandoahVerifier::VerifyOptions options) :
76 _phase(phase),
77 _options(options),
78 _stack(stack),
79 _heap(ShenandoahHeap::heap()),
80 _map(map),
81 _ld(ld),
82 _interior_loc(nullptr),
83 _loc(nullptr),
84 _generation(generation) {
85 if (options._verify_marked == ShenandoahVerifier::_verify_marked_complete_except_references ||
86 options._verify_marked == ShenandoahVerifier::_verify_marked_complete_satb_empty ||
87 options._verify_marked == ShenandoahVerifier::_verify_marked_disable) {
88 // Unknown status for Reference.referent field. Do not touch it, it might be dead.
89 // Normally, barriers would prevent us from seeing the dead referents, but verifier
90 // runs with barriers disabled.
91 _ref_mode = DO_FIELDS_EXCEPT_REFERENT;
92 } else {
93 // Otherwise do all fields.
94 _ref_mode = DO_FIELDS;
95 }
96 }
97
98 ReferenceIterationMode reference_iteration_mode() override {
99 return _ref_mode;
100 }
101
102 private:
103 void check(ShenandoahAsserts::SafeLevel level, oop obj, bool test, const char* label) {
104 if (!test) {
105 ShenandoahAsserts::print_failure(level, obj, _interior_loc, _loc, _phase, label, __FILE__, __LINE__);
106 }
107 }
108
109 template <class T>
110 void do_oop_work(T* p) {
111 T o = RawAccess<>::oop_load(p);
112 if (!CompressedOops::is_null(o)) {
113 // Basic verification should happen before we touch anything else.
114 // For performance reasons, only fully verify non-marked field values.
115 // We are here when the host object for *p is already marked.
116 oop obj = CompressedOops::decode_raw_not_null(o);
117 verify_oop_at_basic(p, obj);
118
119 if (is_instance_ref_klass(ShenandoahForwarding::klass(obj))) {
120 obj = ShenandoahForwarding::get_forwardee(obj);
121 }
122 if (in_generation(obj) && _map->par_mark(obj)) {
123 verify_oop_at(p, obj);
124 _stack->push(ShenandoahVerifierTask(obj));
125 }
126 }
127 }
128
129 bool in_generation(oop obj) const {
130 ShenandoahHeapRegion* region = _heap->heap_region_containing(obj);
131 return _generation->contains(region);
132 }
133
134 void verify_oop(oop obj, bool basic = false) {
135 // Perform consistency checks with gradually decreasing safety level. This guarantees
136 // that failure report would not try to touch something that was not yet verified to be
137 // safe to process.
138
139 check(ShenandoahAsserts::_safe_unknown, obj, _heap->is_in_reserved(obj),
140 "oop must be in heap bounds");
141 check(ShenandoahAsserts::_safe_unknown, obj, is_object_aligned(obj),
142 "oop must be aligned");
143 check(ShenandoahAsserts::_safe_unknown, obj, os::is_readable_pointer(obj),
144 "oop must be accessible");
145
146 ShenandoahHeapRegion *obj_reg = _heap->heap_region_containing(obj);
147
148 narrowKlass nk = 0;
149 const Klass* obj_klass = nullptr;
150 const bool klass_valid = ShenandoahAsserts::extract_klass_safely(obj, nk, obj_klass);
151
152 check(ShenandoahAsserts::_safe_unknown, obj, klass_valid,
153 "Object klass pointer unreadable or invalid");
154
155 // Verify that obj is not in dead space:
156 {
157 // Do this before touching obj->size()
158 check(ShenandoahAsserts::_safe_unknown, obj, Metaspace::contains(obj_klass),
159 "Object klass pointer must go to metaspace");
160
161 HeapWord *obj_addr = cast_from_oop<HeapWord*>(obj);
162 check(ShenandoahAsserts::_safe_unknown, obj, obj_addr < obj_reg->top(),
163 "Object start should be within the region");
164
165 if (!obj_reg->is_humongous()) {
166 check(ShenandoahAsserts::_safe_unknown, obj, (obj_addr + ShenandoahForwarding::size(obj)) <= obj_reg->top(),
167 "Object end should be within the region");
168 } else {
169 size_t humongous_start = obj_reg->index();
170 size_t humongous_end = humongous_start + (ShenandoahForwarding::size(obj) >> ShenandoahHeapRegion::region_size_words_shift());
171 for (size_t idx = humongous_start + 1; idx < humongous_end; idx++) {
172 check(ShenandoahAsserts::_safe_unknown, obj, _heap->get_region(idx)->is_humongous_continuation(),
173 "Humongous object is in continuation that fits it");
174 }
175 }
176
177 check(ShenandoahAsserts::_safe_unknown, obj, obj_reg->is_active(),
178 "Object should be in active region");
179
180 // ------------ obj is safe at this point --------------
181
182 if (basic) {
183 return;
184 }
185
186 switch (_options._verify_liveness) {
187 case ShenandoahVerifier::_verify_liveness_disable:
188 // skip
189 break;
190 case ShenandoahVerifier::_verify_liveness_complete:
191 _ld[obj_reg->index()].add_then_fetch((uint) ShenandoahForwarding::size(obj), memory_order_relaxed);
192 // fallthrough for fast failure for un-live regions:
193 case ShenandoahVerifier::_verify_liveness_conservative:
194 check(ShenandoahAsserts::_safe_oop, obj, obj_reg->has_live() ||
195 (obj_reg->is_old() && _generation->is_young()),
196 "Object must belong to region with live data");
197 break;
198 default:
199 assert(false, "Unhandled liveness verification");
200 }
201 }
202
203 oop fwd = ShenandoahForwarding::get_forwardee_raw_unchecked(obj);
204
205 ShenandoahHeapRegion* fwd_reg = nullptr;
206
207 if (obj != fwd) {
208 check(ShenandoahAsserts::_safe_oop, obj, _heap->is_in_reserved(fwd),
209 "Forwardee must be in heap bounds");
210 check(ShenandoahAsserts::_safe_oop, obj, !CompressedOops::is_null(fwd),
211 "Forwardee is set");
212 check(ShenandoahAsserts::_safe_oop, obj, is_object_aligned(fwd),
213 "Forwardee must be aligned");
214
215 // Do this before touching fwd->size()
216 Klass* fwd_klass = fwd->klass_or_null();
217 check(ShenandoahAsserts::_safe_oop, obj, fwd_klass != nullptr,
218 "Forwardee klass pointer should not be null");
219 check(ShenandoahAsserts::_safe_oop, obj, Metaspace::contains(fwd_klass),
220 "Forwardee klass pointer must go to metaspace");
221 check(ShenandoahAsserts::_safe_oop, obj, obj_klass == fwd_klass,
222 "Forwardee klass pointer must go to metaspace");
223
224 fwd_reg = _heap->heap_region_containing(fwd);
225
226 check(ShenandoahAsserts::_safe_oop, obj, fwd_reg->is_active(),
227 "Forwardee should be in active region");
228
229 // Verify that forwardee is not in the dead space:
230 check(ShenandoahAsserts::_safe_oop, obj, !fwd_reg->is_humongous(),
231 "Should have no humongous forwardees");
232
233 HeapWord *fwd_addr = cast_from_oop<HeapWord *>(fwd);
234 check(ShenandoahAsserts::_safe_oop, obj, fwd_addr < fwd_reg->top(),
235 "Forwardee start should be within the region");
236 check(ShenandoahAsserts::_safe_oop, obj, (fwd_addr + ShenandoahForwarding::size(fwd)) <= fwd_reg->top(),
237 "Forwardee end should be within the region");
238
239 oop fwd2 = ShenandoahForwarding::get_forwardee_raw_unchecked(fwd);
240 check(ShenandoahAsserts::_safe_oop, obj, (fwd == fwd2),
241 "Double forwarding");
242 } else {
243 fwd_reg = obj_reg;
244 }
245
246 // Do additional checks for special objects: their fields can hold metadata as well.
247 // We want to check class loading/unloading did not corrupt them. We can only reasonably
248 // trust the forwarded objects, as the from-space object can have the klasses effectively
249 // dead.
250
251 if (obj_klass == vmClasses::Class_klass()) {
252 const Metadata* klass = fwd->metadata_field(java_lang_Class::klass_offset());
253 check(ShenandoahAsserts::_safe_oop, obj,
254 klass == nullptr || Metaspace::contains(klass),
255 "Mirrored instance class should point to Metaspace");
256
257 const Metadata* array_klass = obj->metadata_field(java_lang_Class::array_klass_offset());
258 check(ShenandoahAsserts::_safe_oop, obj,
259 array_klass == nullptr || Metaspace::contains(array_klass),
260 "Mirrored array class should point to Metaspace");
261 }
262
263 // ------------ obj and fwd are safe at this point --------------
264 switch (_options._verify_marked) {
265 case ShenandoahVerifier::_verify_marked_disable:
266 // skip
267 break;
268 case ShenandoahVerifier::_verify_marked_incomplete:
269 check(ShenandoahAsserts::_safe_all, obj, _heap->marking_context()->is_marked(obj),
270 "Must be marked in incomplete bitmap");
271 break;
272 case ShenandoahVerifier::_verify_marked_complete:
273 check(ShenandoahAsserts::_safe_all, obj, _generation->complete_marking_context()->is_marked(obj),
274 "Must be marked in complete bitmap");
275 break;
276 case ShenandoahVerifier::_verify_marked_complete_except_references:
277 case ShenandoahVerifier::_verify_marked_complete_satb_empty:
278 check(ShenandoahAsserts::_safe_all, obj, _generation->complete_marking_context()->is_marked(obj),
279 "Must be marked in complete bitmap, except j.l.r.Reference referents");
280 break;
281 default:
282 assert(false, "Unhandled mark verification");
283 }
284
285 switch (_options._verify_forwarded) {
286 case ShenandoahVerifier::_verify_forwarded_disable:
287 // skip
288 break;
289 case ShenandoahVerifier::_verify_forwarded_none: {
290 check(ShenandoahAsserts::_safe_all, obj, (obj == fwd),
291 "Should not be forwarded");
292 break;
293 }
294 case ShenandoahVerifier::_verify_forwarded_allow: {
295 if (obj != fwd) {
296 check(ShenandoahAsserts::_safe_all, obj, obj_reg != fwd_reg,
297 "Forwardee should be in another region");
298 }
299 break;
300 }
301 default:
302 assert(false, "Unhandled forwarding verification");
303 }
304
305 switch (_options._verify_cset) {
306 case ShenandoahVerifier::_verify_cset_disable:
307 // skip
308 break;
309 case ShenandoahVerifier::_verify_cset_none:
310 check(ShenandoahAsserts::_safe_all, obj, !_heap->in_collection_set(obj),
311 "Should not have references to collection set");
312 break;
313 case ShenandoahVerifier::_verify_cset_forwarded:
314 if (_heap->in_collection_set(obj)) {
315 check(ShenandoahAsserts::_safe_all, obj, (obj != fwd),
316 "Object in collection set, should have forwardee");
317 }
318 break;
319 default:
320 assert(false, "Unhandled cset verification");
321 }
322
323 }
324
325 public:
326 /**
327 * Verify object with known interior reference.
328 * @param p interior reference where the object is referenced from; can be off-heap
329 * @param obj verified object
330 */
331 template <class T>
332 void verify_oop_at(T* p, oop obj) {
333 _interior_loc = p;
334 verify_oop(obj);
335 _interior_loc = nullptr;
336 }
337
338 /**
339 * Verify object with known interior reference, with only basic verification.
340 * @param p interior reference where the object is referenced from; can be off-heap
341 * @param obj verified object
342 */
343 template <class T>
344 void verify_oop_at_basic(T* p, oop obj) {
345 _interior_loc = p;
346 verify_oop(obj, /* basic = */ true);
347 _interior_loc = nullptr;
348 }
349
350 /**
351 * Verify object without known interior reference.
352 * Useful when picking up the object at known offset in heap,
353 * but without knowing what objects reference it.
354 * @param obj verified object
355 */
356 void verify_oop_standalone(oop obj) {
357 _interior_loc = nullptr;
358 verify_oop(obj);
359 _interior_loc = nullptr;
360 }
361
362 /**
363 * Verify oop fields from this object.
364 * @param obj host object for verified fields
365 */
366 void verify_oops_from(oop obj) {
367 _loc = obj;
368 // oop_iterate() can not deal with forwarded objects, because
369 // it needs to load klass(), which may be overridden by the
370 // forwarding pointer.
371 oop fwd = ShenandoahForwarding::get_forwardee_raw(obj);
372 fwd->oop_iterate(this);
373 _loc = nullptr;
374 }
375
376 void do_oop(oop* p) override { do_oop_work(p); }
377 void do_oop(narrowOop* p) override { do_oop_work(p); }
378 };
379
380 // This closure computes the amounts of used, committed, and garbage memory and the number of regions contained within
381 // a subset (e.g. the young generation or old generation) of the total heap.
382 class ShenandoahCalculateRegionStatsClosure : public ShenandoahHeapRegionClosure {
383 private:
384 size_t _used, _committed, _garbage, _regions, _humongous_waste, _trashed_regions, _trashed_used;
385 size_t _region_size_bytes, _min_free_size;
386 public:
387 ShenandoahCalculateRegionStatsClosure() :
388 _used(0), _committed(0), _garbage(0), _regions(0), _humongous_waste(0), _trashed_regions(0), _trashed_used(0)
389 {
390 _region_size_bytes = ShenandoahHeapRegion::region_size_bytes();
391 // Retired regions are not necessarily filled, thouugh their remnant memory is considered used.
392 _min_free_size = PLAB::min_size() * HeapWordSize;
393 };
394
395 void heap_region_do(ShenandoahHeapRegion* r) override {
396 if (r->is_cset() || r->is_trash()) {
397 // Count the entire cset or trashed (formerly cset) region as used
398 // Note: Immediate garbage trash regions were never in the cset.
399 _used += _region_size_bytes;
400 _garbage += _region_size_bytes - r->get_live_data_bytes();
401 if (r->is_trash()) {
402 _trashed_regions++;
403 _trashed_used += _region_size_bytes;
404 }
405 } else {
406 if (r->is_humongous()) {
407 _used += _region_size_bytes;
408 _garbage += _region_size_bytes - r->get_live_data_bytes();
409 _humongous_waste += r->free();
410 } else {
411 size_t alloc_capacity = r->free();
412 if (alloc_capacity < _min_free_size) {
413 // this region has been retired already, count it as entirely consumed
414 alloc_capacity = 0;
415 }
416 size_t bytes_used_in_region = _region_size_bytes - alloc_capacity;
417 size_t bytes_garbage_in_region = bytes_used_in_region - r->get_live_data_bytes();
418 size_t waste_bytes = r->free();
419 _used += bytes_used_in_region;
420 _garbage += bytes_garbage_in_region;
421 }
422 }
423 _committed += r->is_committed() ? _region_size_bytes : 0;
424 _regions++;
425 log_debug(gc)("ShenandoahCalculateRegionStatsClosure: adding %zu for %s Region %zu, yielding: %zu",
426 r->used(), (r->is_humongous() ? "humongous" : "regular"), r->index(), _used);
427 }
428
429 size_t used() const { return _used; }
430 size_t used_after_recycle() const { return _used - _trashed_used; }
431 size_t committed() const { return _committed; }
432 size_t garbage() const { return _garbage; }
433 size_t regions() const { return _regions; }
434 size_t trashed_regions() const { return _trashed_regions; }
435 size_t waste() const { return _humongous_waste; }
436
437 // span is the total memory affiliated with these stats (some of which is in use and other is available)
438 size_t span() const { return _regions * ShenandoahHeapRegion::region_size_bytes(); }
439 size_t non_trashed_span() const {
440 assert(_regions >= _trashed_regions, "sanity");
441 return (_regions - _trashed_regions) * ShenandoahHeapRegion::region_size_bytes();
442 }
443 size_t non_trashed_committed() const {
444 assert(_committed >= _trashed_regions * ShenandoahHeapRegion::region_size_bytes(), "sanity");
445 return _committed - (_trashed_regions * ShenandoahHeapRegion::region_size_bytes());
446 }
447 };
448
449 class ShenandoahGenerationStatsClosure : public ShenandoahHeapRegionClosure {
450 public:
451 ShenandoahCalculateRegionStatsClosure _old;
452 ShenandoahCalculateRegionStatsClosure _young;
453 ShenandoahCalculateRegionStatsClosure _global;
454
455 void heap_region_do(ShenandoahHeapRegion* r) override {
456 switch (r->affiliation()) {
457 case FREE:
458 return;
459 case YOUNG_GENERATION:
460 _young.heap_region_do(r);
461 _global.heap_region_do(r);
462 break;
463 case OLD_GENERATION:
464 _old.heap_region_do(r);
465 _global.heap_region_do(r);
466 break;
467 default:
468 ShouldNotReachHere();
469 }
470 }
471
472 static void log_usage(ShenandoahGeneration* generation, ShenandoahCalculateRegionStatsClosure& stats) {
473 log_debug(gc)("Safepoint verification: %s verified usage: %zu%s, recorded usage: %zu%s",
474 generation->name(),
475 byte_size_in_proper_unit(generation->used()), proper_unit_for_byte_size(generation->used()),
476 byte_size_in_proper_unit(stats.used()), proper_unit_for_byte_size(stats.used()));
477 }
478
479 static void validate_usage(const bool adjust_for_padding, const bool adjust_for_trash,
480 const char* label, ShenandoahGeneration* generation, ShenandoahCalculateRegionStatsClosure& stats) {
481 ShenandoahHeap* heap = ShenandoahHeap::heap();
482 size_t generation_used = generation->used();
483 size_t generation_used_regions = generation->used_regions();
484
485 size_t stats_used = adjust_for_trash? stats.used_after_recycle(): stats.used();
486 guarantee(stats_used == generation_used,
487 "%s: generation (%s) used size must be consistent: generation-used: " PROPERFMT ", regions-used: " PROPERFMT,
488 label, generation->name(), PROPERFMTARGS(generation_used), PROPERFMTARGS(stats_used));
489
490 size_t stats_regions = adjust_for_trash? stats.regions() - stats.trashed_regions(): stats.regions();
491 guarantee(stats_regions == generation_used_regions,
492 "%s: generation (%s) used regions (%zu) must equal regions that are in use (%zu)%s",
493 label, generation->name(), generation->used_regions(), stats_regions,
494 adjust_for_trash? " (after adjusting for trash)": "");
495
496 size_t generation_capacity = generation->max_capacity();
497 guarantee(stats.non_trashed_span() <= generation_capacity,
498 "%s: generation (%s) size spanned by regions (%zu) * region size (" PROPERFMT
499 ") must not exceed current capacity (" PROPERFMT ")",
500 label, generation->name(), stats.regions(), PROPERFMTARGS(ShenandoahHeapRegion::region_size_bytes()),
501 PROPERFMTARGS(generation_capacity));
502
503 size_t humongous_waste = generation->get_humongous_waste();
504 guarantee(stats.waste() == humongous_waste,
505 "%s: generation (%s) humongous waste must be consistent: generation: " PROPERFMT ", regions: " PROPERFMT,
506 label, generation->name(), PROPERFMTARGS(humongous_waste), PROPERFMTARGS(stats.waste()));
507 }
508 };
509
510 class ShenandoahVerifyHeapRegionClosure : public ShenandoahHeapRegionClosure {
511 private:
512 ShenandoahHeap* _heap;
513 const char* _phase;
514 ShenandoahVerifier::VerifyRegions _regions;
515 public:
516 ShenandoahVerifyHeapRegionClosure(const char* phase, ShenandoahVerifier::VerifyRegions regions) :
517 _heap(ShenandoahHeap::heap()),
518 _phase(phase),
519 _regions(regions) {};
520
521 void print_failure(ShenandoahHeapRegion* r, const char* label) {
522 ResourceMark rm;
523
524 ShenandoahMessageBuffer msg("Shenandoah verification failed; %s: %s\n\n", _phase, label);
525
526 stringStream ss;
527 r->print_on(&ss);
528 msg.append("%s", ss.as_string());
529
530 report_vm_error(__FILE__, __LINE__, msg.buffer());
531 }
532
533 void verify(ShenandoahHeapRegion* r, bool test, const char* msg) {
534 if (!test) {
535 print_failure(r, msg);
536 }
537 }
538
539 void heap_region_do(ShenandoahHeapRegion* r) override {
540 switch (_regions) {
541 case ShenandoahVerifier::_verify_regions_disable:
542 break;
543 case ShenandoahVerifier::_verify_regions_notrash:
544 verify(r, !r->is_trash(),
545 "Should not have trash regions");
546 break;
547 case ShenandoahVerifier::_verify_regions_nocset:
548 verify(r, !r->is_cset(),
549 "Should not have cset regions");
550 break;
551 case ShenandoahVerifier::_verify_regions_notrash_nocset:
552 verify(r, !r->is_trash(),
553 "Should not have trash regions");
554 verify(r, !r->is_cset(),
555 "Should not have cset regions");
556 break;
557 default:
558 ShouldNotReachHere();
559 }
560
561 verify(r, r->capacity() == ShenandoahHeapRegion::region_size_bytes(),
562 "Capacity should match region size");
563
564 verify(r, r->bottom() <= r->top(),
565 "Region top should not be less than bottom");
566
567 verify(r, r->bottom() <= _heap->marking_context()->top_at_mark_start(r),
568 "Region TAMS should not be less than bottom");
569
570 verify(r, _heap->marking_context()->top_at_mark_start(r) <= r->top(),
571 "Complete TAMS should not be larger than top");
572
573 verify(r, r->get_live_data_bytes() <= r->capacity(),
574 "Live data cannot be larger than capacity");
575
576 verify(r, r->garbage() <= r->capacity(),
577 "Garbage cannot be larger than capacity");
578
579 verify(r, r->used() <= r->capacity(),
580 "Used cannot be larger than capacity");
581
582 verify(r, r->get_shared_allocs() <= r->capacity(),
583 "Shared alloc count should not be larger than capacity");
584
585 verify(r, r->get_tlab_allocs() <= r->capacity(),
586 "TLAB alloc count should not be larger than capacity");
587
588 verify(r, r->get_gclab_allocs() <= r->capacity(),
589 "GCLAB alloc count should not be larger than capacity");
590
591 verify(r, r->get_plab_allocs() <= r->capacity(),
592 "PLAB alloc count should not be larger than capacity");
593
594 verify(r, r->get_shared_allocs() + r->get_tlab_allocs() + r->get_gclab_allocs() + r->get_plab_allocs() == r->used(),
595 "Accurate accounting: shared + TLAB + GCLAB + PLAB = used");
596
597 verify(r, !r->is_empty() || !r->has_live(),
598 "Empty regions should not have live data");
599
600 verify(r, r->is_cset() == _heap->collection_set()->is_in(r),
601 "Transitional: region flags and collection set agree");
602 }
603 };
604
605 class ShenandoahVerifierReachableTask : public WorkerTask {
606 private:
607 const char* _label;
608 ShenandoahVerifier::VerifyOptions _options;
609 ShenandoahHeap* _heap;
610 ShenandoahLivenessData* _ld;
611 MarkBitMap* _bitmap;
612 Atomic<size_t> _processed;
613 ShenandoahGeneration* _generation;
614
615 public:
616 ShenandoahVerifierReachableTask(ShenandoahGeneration* generation,
617 MarkBitMap* bitmap,
618 ShenandoahLivenessData* ld,
619 const char* label,
620 ShenandoahVerifier::VerifyOptions options) :
621 WorkerTask("Shenandoah Verifier Reachable Objects"),
622 _label(label),
623 _options(options),
624 _heap(ShenandoahHeap::heap()),
625 _ld(ld),
626 _bitmap(bitmap),
627 _processed(0),
628 _generation(generation) {};
629
630 size_t processed() const {
631 return _processed.load_relaxed();
632 }
633
634 void work(uint worker_id) override {
635 ResourceMark rm;
636 ShenandoahVerifierStack stack;
637
638 // On level 2, we need to only check the roots once.
639 // On level 3, we want to check the roots, and seed the local stack.
640 // It is a lesser evil to accept multiple root scans at level 3, because
641 // extended parallelism would buy us out.
642 if (((ShenandoahVerifyLevel == 2) && (worker_id == 0))
643 || (ShenandoahVerifyLevel >= 3)) {
644 ShenandoahVerifyOopClosure cl(_generation, &stack, _bitmap, _ld,
645 ShenandoahMessageBuffer("%s, Roots", _label),
646 _options);
647 if (_heap->unload_classes()) {
648 ShenandoahRootVerifier::strong_roots_do(&cl, _generation);
649 } else {
650 ShenandoahRootVerifier::roots_do(&cl, _generation);
651 }
652 }
653
654 size_t processed = 0;
655
656 if (ShenandoahVerifyLevel >= 3) {
657 ShenandoahVerifyOopClosure cl(_generation, &stack, _bitmap, _ld,
658 ShenandoahMessageBuffer("%s, Reachable", _label),
659 _options);
660 while (!stack.is_empty()) {
661 processed++;
662 ShenandoahVerifierTask task = stack.pop();
663 cl.verify_oops_from(task.obj());
664 }
665 }
666
667 _processed.add_then_fetch(processed, memory_order_relaxed);
668 }
669 };
670
671 class ShenandoahVerifyNoIncompleteSatbBuffers : public ThreadClosure {
672 public:
673 void do_thread(Thread* thread) override {
674 SATBMarkQueue& queue = ShenandoahThreadLocalData::satb_mark_queue(thread);
675 if (!queue.is_empty()) {
676 fatal("All SATB buffers should have been flushed during mark");
677 }
678 }
679 };
680
681 class ShenandoahVerifierMarkedRegionTask : public WorkerTask {
682 private:
683 const char* _label;
684 ShenandoahVerifier::VerifyOptions _options;
685 ShenandoahHeap *_heap;
686 MarkBitMap* _bitmap;
687 ShenandoahLivenessData* _ld;
688 Atomic<size_t> _claimed;
689 Atomic<size_t> _processed;
690 ShenandoahGeneration* _generation;
691
692 public:
693 ShenandoahVerifierMarkedRegionTask(ShenandoahGeneration* generation,
694 MarkBitMap* bitmap,
695 ShenandoahLivenessData* ld,
696 const char* label,
697 ShenandoahVerifier::VerifyOptions options) :
698 WorkerTask("Shenandoah Verifier Marked Objects"),
699 _label(label),
700 _options(options),
701 _heap(ShenandoahHeap::heap()),
702 _bitmap(bitmap),
703 _ld(ld),
704 _claimed(0),
705 _processed(0),
706 _generation(generation) {}
707
708 size_t processed() {
709 return _processed.load_relaxed();
710 }
711
712 void work(uint worker_id) override {
713 if (_options._verify_marked == ShenandoahVerifier::_verify_marked_complete_satb_empty) {
714 ShenandoahVerifyNoIncompleteSatbBuffers verify_satb;
715 Threads::threads_do(&verify_satb);
716 }
717
718 ShenandoahVerifierStack stack;
719 ShenandoahVerifyOopClosure cl(_generation, &stack, _bitmap, _ld,
720 ShenandoahMessageBuffer("%s, Marked", _label),
721 _options);
722
723 while (true) {
724 size_t v = _claimed.fetch_then_add(1u, memory_order_relaxed);
725 if (v < _heap->num_regions()) {
726 ShenandoahHeapRegion* r = _heap->get_region(v);
727 if (!in_generation(r)) {
728 continue;
729 }
730
731 if (!r->is_humongous() && !r->is_trash()) {
732 work_regular(r, stack, cl);
733 } else if (r->is_humongous_start()) {
734 work_humongous(r, stack, cl);
735 }
736 } else {
737 break;
738 }
739 }
740 }
741
742 bool in_generation(ShenandoahHeapRegion* r) const {
743 return _generation->contains(r);
744 }
745
746 virtual void work_humongous(ShenandoahHeapRegion *r, ShenandoahVerifierStack& stack, ShenandoahVerifyOopClosure& cl) {
747 size_t processed = 0;
748 HeapWord* obj = r->bottom();
749 if (_generation->complete_marking_context()->is_marked(cast_to_oop(obj))) {
750 verify_and_follow(obj, stack, cl, &processed);
751 }
752 _processed.add_then_fetch(processed, memory_order_relaxed);
753 }
754
755 virtual void work_regular(ShenandoahHeapRegion *r, ShenandoahVerifierStack &stack, ShenandoahVerifyOopClosure &cl) {
756 size_t processed = 0;
757 ShenandoahMarkingContext* ctx = _generation->complete_marking_context();
758 HeapWord* tams = ctx->top_at_mark_start(r);
759
760 // Bitmaps, before TAMS
761 if (tams > r->bottom()) {
762 HeapWord* start = r->bottom();
763 HeapWord* addr = ctx->get_next_marked_addr(start, tams);
764
765 while (addr < tams) {
766 verify_and_follow(addr, stack, cl, &processed);
767 addr += 1;
768 if (addr < tams) {
769 addr = ctx->get_next_marked_addr(addr, tams);
770 }
771 }
772 }
773
774 // Size-based, after TAMS
775 {
776 HeapWord* limit = r->top();
777 HeapWord* addr = tams;
778
779 while (addr < limit) {
780 verify_and_follow(addr, stack, cl, &processed);
781 addr += ShenandoahForwarding::size(cast_to_oop(addr));
782 }
783 }
784
785 _processed.add_then_fetch(processed, memory_order_relaxed);
786 }
787
788 void verify_and_follow(HeapWord *addr, ShenandoahVerifierStack &stack, ShenandoahVerifyOopClosure &cl, size_t *processed) {
789 if (!_bitmap->par_mark(addr)) return;
790
791 // Verify the object itself:
792 oop obj = cast_to_oop(addr);
793 cl.verify_oop_standalone(obj);
794
795 // Verify everything reachable from that object too, hopefully realizing
796 // everything was already marked, and never touching further:
797 if (!is_instance_ref_klass(ShenandoahForwarding::klass(obj))) {
798 cl.verify_oops_from(obj);
799 (*processed)++;
800 }
801 while (!stack.is_empty()) {
802 ShenandoahVerifierTask task = stack.pop();
803 cl.verify_oops_from(task.obj());
804 (*processed)++;
805 }
806 }
807 };
808
809 class VerifyThreadGCState : public ThreadClosure {
810 private:
811 const char* const _label;
812 char const _expected;
813
814 public:
815 VerifyThreadGCState(const char* label, char expected) : _label(label), _expected(expected) {}
816 void do_thread(Thread* t) override {
817 char actual = ShenandoahThreadLocalData::gc_state(t);
818 if (!verify_gc_state(actual, _expected)) {
819 fatal("%s: Thread %s: expected gc-state %d, actual %d", _label, t->name(), _expected, actual);
820 }
821 }
822
823 static bool verify_gc_state(char actual, char expected) {
824 // Old generation marking is allowed in all states.
825 if (ShenandoahHeap::heap()->mode()->is_generational()) {
826 return ((actual & ~(ShenandoahHeap::OLD_MARKING | ShenandoahHeap::MARKING)) == expected);
827 } else {
828 assert((actual & ShenandoahHeap::OLD_MARKING) == 0, "Should not mark old in non-generational mode");
829 return (actual == expected);
830 }
831 }
832 };
833
834 void ShenandoahVerifier::verify_at_safepoint(ShenandoahGeneration* generation,
835 const char* label,
836 VerifyRememberedSet remembered,
837 VerifyForwarded forwarded,
838 VerifyMarked marked,
839 VerifyCollectionSet cset,
840 VerifyLiveness liveness,
841 VerifyRegions regions,
842 VerifySize sizeness,
843 VerifyGCState gcstate) {
844 guarantee(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "only when nothing else happens");
845 guarantee(ShenandoahVerify, "only when enabled, and bitmap is initialized in ShenandoahHeap::initialize");
846
847 ShenandoahHeap::heap()->propagate_gc_state_to_all_threads();
848
849 // Avoid side-effect of changing workers' active thread count, but bypass concurrent/parallel protocol check
850 ShenandoahPushWorkerScope verify_worker_scope(_heap->workers(), _heap->max_workers(), false /*bypass check*/);
851
852 log_info(gc,start)("Verify %s, Level %zd", label, ShenandoahVerifyLevel);
853
854 // GC state checks
855 {
856 char expected = -1;
857 bool enabled;
858 switch (gcstate) {
859 case _verify_gcstate_disable:
860 enabled = false;
861 break;
862 case _verify_gcstate_forwarded:
863 enabled = true;
864 expected = ShenandoahHeap::HAS_FORWARDED;
865 break;
866 case _verify_gcstate_updating:
867 enabled = true;
868 expected = ShenandoahHeap::HAS_FORWARDED | ShenandoahHeap::UPDATE_REFS;
869 break;
870 case _verify_gcstate_stable:
871 enabled = true;
872 expected = ShenandoahHeap::STABLE;
873 break;
874 case _verify_gcstate_stable_weakroots:
875 enabled = true;
876 expected = ShenandoahHeap::STABLE;
877 if (!_heap->is_stw_gc_in_progress()) {
878 // Only concurrent GC sets this.
879 expected |= ShenandoahHeap::WEAK_ROOTS;
880 }
881 break;
882 default:
883 enabled = false;
884 assert(false, "Unhandled gc-state verification");
885 }
886
887 if (enabled) {
888 char actual = _heap->gc_state();
889
890 bool is_marking = (actual & ShenandoahHeap::MARKING);
891 bool is_marking_young_or_old = (actual & (ShenandoahHeap::YOUNG_MARKING | ShenandoahHeap::OLD_MARKING));
892 assert(is_marking == is_marking_young_or_old, "MARKING iff (YOUNG_MARKING or OLD_MARKING), gc_state is: %x", actual);
893
894 // Old generation marking is allowed in all states.
895 if (!VerifyThreadGCState::verify_gc_state(actual, expected)) {
896 fatal("%s: Global gc-state: expected %d, actual %d", label, expected, actual);
897 }
898
899 VerifyThreadGCState vtgcs(label, expected);
900 Threads::java_threads_do(&vtgcs);
901 }
902 }
903
904 // Deactivate barriers temporarily: Verifier wants plain heap accesses
905 ShenandoahGCStateResetter resetter;
906
907 // Heap size checks
908 {
909 ShenandoahHeapLocker lock(_heap->lock());
910
911 ShenandoahCalculateRegionStatsClosure cl;
912 _heap->heap_region_iterate(&cl);
913 size_t heap_used;
914 if (_heap->mode()->is_generational() && (sizeness == _verify_size_adjusted_for_padding)) {
915 // Prior to evacuation, regular regions that are to be evacuated in place are padded to prevent further allocations
916 // but this padding is already represented in _heap->used()
917 heap_used = _heap->used();
918 } else if (sizeness != _verify_size_disable) {
919 heap_used = _heap->used();
920 }
921 if (sizeness != _verify_size_disable) {
922 size_t cl_size = (sizeness == _verify_size_exact_including_trash)? cl.used(): cl.used_after_recycle();
923 guarantee(cl_size == heap_used,
924 "%s: heap used size must be consistent: heap-used = %zu%s, regions-used = %zu%s",
925 label,
926 byte_size_in_proper_unit(heap_used), proper_unit_for_byte_size(heap_used),
927 byte_size_in_proper_unit(cl_size), proper_unit_for_byte_size(cl_size));
928 }
929 size_t heap_committed = _heap->committed();
930 guarantee(cl.committed() == heap_committed,
931 "%s: heap committed size must be consistent: heap-committed = %zu%s, regions-committed = %zu%s",
932 label,
933 byte_size_in_proper_unit(heap_committed), proper_unit_for_byte_size(heap_committed),
934 byte_size_in_proper_unit(cl.committed()), proper_unit_for_byte_size(cl.committed()));
935 }
936
937 log_debug(gc)("Safepoint verification finished heap usage verification");
938
939 if (_heap->mode()->is_generational()) {
940 ShenandoahHeapLocker lock(_heap->lock());
941
942 switch (remembered) {
943 case _verify_remembered_disable:
944 break;
945 case _verify_remembered_before_marking:
946 log_debug(gc)("Safepoint verification of remembered set at mark");
947 verify_rem_set_before_mark();
948 break;
949 case _verify_remembered_before_updating_references:
950 log_debug(gc)("Safepoint verification of remembered set at update ref");
951 verify_rem_set_before_update_ref();
952 break;
953 case _verify_remembered_after_full_gc:
954 log_debug(gc)("Safepoint verification of remembered set after full gc");
955 verify_rem_set_after_full_gc();
956 break;
957 default:
958 fatal("Unhandled remembered set verification mode");
959 }
960
961 ShenandoahGenerationStatsClosure cl;
962 _heap->heap_region_iterate(&cl);
963
964 if (LogTarget(Debug, gc)::is_enabled()) {
965 ShenandoahGenerationStatsClosure::log_usage(_heap->old_generation(), cl._old);
966 ShenandoahGenerationStatsClosure::log_usage(_heap->young_generation(), cl._young);
967 ShenandoahGenerationStatsClosure::log_usage(_heap->global_generation(), cl._global);
968 }
969 if (sizeness == _verify_size_adjusted_for_padding) {
970 ShenandoahGenerationStatsClosure::validate_usage(false, true, label, _heap->old_generation(), cl._old);
971 ShenandoahGenerationStatsClosure::validate_usage(true, true, label, _heap->young_generation(), cl._young);
972 ShenandoahGenerationStatsClosure::validate_usage(true, true, label, _heap->global_generation(), cl._global);
973 } else if (sizeness == _verify_size_exact || sizeness == _verify_size_exact_including_trash) {
974 bool adjust_trash = (sizeness == _verify_size_exact);
975 ShenandoahGenerationStatsClosure::validate_usage(false, adjust_trash, label, _heap->old_generation(), cl._old);
976 ShenandoahGenerationStatsClosure::validate_usage(false, adjust_trash, label, _heap->young_generation(), cl._young);
977 ShenandoahGenerationStatsClosure::validate_usage(false, adjust_trash, label, _heap->global_generation(), cl._global);
978 }
979 // else: sizeness must equal _verify_size_disable
980 }
981
982 log_debug(gc)("Safepoint verification finished remembered set verification");
983
984 // Internal heap region checks
985 if (ShenandoahVerifyLevel >= 1) {
986 ShenandoahVerifyHeapRegionClosure cl(label, regions);
987 generation->heap_region_iterate(&cl);
988 }
989
990 log_debug(gc)("Safepoint verification finished heap region closure verification");
991
992 OrderAccess::fence();
993
994 if (UseTLAB) {
995 _heap->labs_make_parsable();
996 }
997
998 // Allocate temporary bitmap for storing marking wavefront:
999 _verification_bit_map->clear();
1000
1001 // Allocate temporary array for storing liveness data
1002 ShenandoahLivenessData* ld = NEW_C_HEAP_ARRAY(ShenandoahLivenessData, _heap->num_regions(), mtGC);
1003 Copy::fill_to_bytes((void*)ld, _heap->num_regions()*sizeof(ShenandoahLivenessData), 0);
1004
1005 const VerifyOptions& options = ShenandoahVerifier::VerifyOptions(forwarded, marked, cset, liveness, regions, gcstate);
1006
1007 // Steps 1-2. Scan root set to get initial reachable set. Finish walking the reachable heap.
1008 // This verifies what application can see, since it only cares about reachable objects.
1009 size_t count_reachable = 0;
1010 if (ShenandoahVerifyLevel >= 2) {
1011 ShenandoahVerifierReachableTask task(generation, _verification_bit_map, ld, label, options);
1012 _heap->workers()->run_task(&task);
1013 count_reachable = task.processed();
1014 }
1015
1016 log_debug(gc)("Safepoint verification finished getting initial reachable set");
1017
1018 // Step 3. Walk marked objects. Marked objects might be unreachable. This verifies what collector,
1019 // not the application, can see during the region scans. There is no reason to process the objects
1020 // that were already verified, e.g. those marked in verification bitmap. There is interaction with TAMS:
1021 // before TAMS, we verify the bitmaps, if available; after TAMS, we walk until the top(). It mimics
1022 // what marked_object_iterate is doing, without calling into that optimized (and possibly incorrect)
1023 // version
1024
1025 size_t count_marked = 0;
1026 if (ShenandoahVerifyLevel >= 4 &&
1027 (marked == _verify_marked_complete ||
1028 marked == _verify_marked_complete_except_references ||
1029 marked == _verify_marked_complete_satb_empty)) {
1030 guarantee(generation->is_mark_complete(), "Marking context should be complete");
1031 ShenandoahVerifierMarkedRegionTask task(generation, _verification_bit_map, ld, label, options);
1032 _heap->workers()->run_task(&task);
1033 count_marked = task.processed();
1034 } else {
1035 guarantee(ShenandoahVerifyLevel < 4 || marked == _verify_marked_incomplete || marked == _verify_marked_disable, "Should be");
1036 }
1037
1038 log_debug(gc)("Safepoint verification finished walking marked objects");
1039
1040 // Step 4. Verify accumulated liveness data, if needed. Only reliable if verification level includes
1041 // marked objects.
1042
1043 if (ShenandoahVerifyLevel >= 4 && marked == _verify_marked_complete && liveness == _verify_liveness_complete) {
1044 for (size_t i = 0; i < _heap->num_regions(); i++) {
1045 ShenandoahHeapRegion* r = _heap->get_region(i);
1046 if (!generation->contains(r)) {
1047 continue;
1048 }
1049
1050 juint verf_live = 0;
1051 if (r->is_humongous()) {
1052 // For humongous objects, test if start region is marked live, and if so,
1053 // all humongous regions in that chain have live data equal to their "used".
1054 juint start_live = ld[r->humongous_start_region()->index()].load_relaxed();
1055 if (start_live > 0) {
1056 verf_live = (juint)(r->used() / HeapWordSize);
1057 }
1058 } else {
1059 verf_live = ld[r->index()].load_relaxed();
1060 }
1061
1062 size_t reg_live = r->get_live_data_words();
1063 if (reg_live != verf_live) {
1064 stringStream ss;
1065 r->print_on(&ss);
1066 fatal("%s: Live data should match: region-live = %zu, verifier-live = " UINT32_FORMAT "\n%s",
1067 label, reg_live, verf_live, ss.freeze());
1068 }
1069 }
1070 }
1071
1072 log_debug(gc)("Safepoint verification finished accumulation of liveness data");
1073 log_info(gc)("Verify %s, Level %zd (%zu reachable, %zu marked)",
1074 label, ShenandoahVerifyLevel, count_reachable, count_marked);
1075
1076 FREE_C_HEAP_ARRAY(ShenandoahLivenessData, ld);
1077 }
1078
1079 void ShenandoahVerifier::verify_generic(ShenandoahGeneration* generation, VerifyOption vo) {
1080 verify_at_safepoint(
1081 generation,
1082 "Generic Verification",
1083 _verify_remembered_disable, // do not verify remembered set
1084 _verify_forwarded_allow, // conservatively allow forwarded
1085 _verify_marked_disable, // do not verify marked: lots ot time wasted checking dead allocations
1086 _verify_cset_disable, // cset may be inconsistent
1087 _verify_liveness_disable, // no reliable liveness data
1088 _verify_regions_disable, // no reliable region data
1089 _verify_size_disable, // no reliable sizing data
1090 _verify_gcstate_disable // no data about gcstate
1091 );
1092 }
1093
1094 void ShenandoahVerifier::verify_before_concmark(ShenandoahGeneration* generation) {
1095 VerifyRememberedSet verify_remembered_set = _verify_remembered_before_marking;
1096 if (_heap->mode()->is_generational() &&
1097 !_heap->old_generation()->is_mark_complete()) {
1098 // Before marking in generational mode, remembered set can't be verified w/o complete old marking.
1099 verify_remembered_set = _verify_remembered_disable;
1100 }
1101 verify_at_safepoint(
1102 generation,
1103 "Before Mark",
1104 verify_remembered_set,
1105 // verify read-only remembered set from bottom() to top()
1106 _verify_forwarded_none, // UR should have fixed up
1107 _verify_marked_disable, // do not verify marked: lots ot time wasted checking dead allocations
1108 _verify_cset_none, // UR should have fixed this
1109 _verify_liveness_disable, // no reliable liveness data
1110 _verify_regions_notrash, // no trash regions
1111 _verify_size_exact, // expect generation and heap sizes to match exactly
1112 _verify_gcstate_stable // there are no forwarded objects
1113 );
1114 }
1115
1116 void ShenandoahVerifier::verify_after_concmark(ShenandoahGeneration* generation) {
1117 verify_at_safepoint(
1118 generation,
1119 "After Mark",
1120 _verify_remembered_disable, // do not verify remembered set
1121 _verify_forwarded_none, // no forwarded references
1122 _verify_marked_complete_satb_empty, // bitmaps as precise as we can get, except dangling j.l.r.Refs
1123 _verify_cset_none, // no references to cset anymore
1124 _verify_liveness_complete, // liveness data must be complete here
1125 _verify_regions_disable, // trash regions not yet recycled
1126 _verify_size_exact, // expect generation and heap sizes to match exactly
1127 _verify_gcstate_stable_weakroots // heap is still stable, weakroots are in progress
1128 );
1129 }
1130
1131 void ShenandoahVerifier::verify_after_concmark_with_promotions(ShenandoahGeneration* generation) {
1132 verify_at_safepoint(
1133 generation,
1134 "After Mark",
1135 _verify_remembered_disable, // do not verify remembered set
1136 _verify_forwarded_none, // no forwarded references
1137 _verify_marked_complete_satb_empty, // bitmaps as precise as we can get, except dangling j.l.r.Refs
1138 _verify_cset_none, // no references to cset anymore
1139 _verify_liveness_complete, // liveness data must be complete here
1140 _verify_regions_disable, // trash regions not yet recycled
1141 _verify_size_adjusted_for_padding, // expect generation and heap sizes to match after adjustments
1142 // for promote in place padding
1143 _verify_gcstate_stable_weakroots // heap is still stable, weakroots are in progress
1144 );
1145 }
1146
1147 void ShenandoahVerifier::verify_before_evacuation(ShenandoahGeneration* generation) {
1148 verify_at_safepoint(
1149 generation,
1150 "Before Evacuation",
1151 _verify_remembered_disable, // do not verify remembered set
1152 _verify_forwarded_none, // no forwarded references
1153 _verify_marked_complete_except_references, // walk over marked objects too
1154 _verify_cset_disable, // non-forwarded references to cset expected
1155 _verify_liveness_complete, // liveness data must be complete here
1156 _verify_regions_disable, // trash regions not yet recycled
1157 _verify_size_adjusted_for_padding, // expect generation and heap sizes to match after adjustments
1158 // for promote in place padding
1159 _verify_gcstate_stable_weakroots // heap is still stable, weakroots are in progress
1160 );
1161 }
1162
1163 void ShenandoahVerifier::verify_before_update_refs(ShenandoahGeneration* generation) {
1164 VerifyRememberedSet verify_remembered_set = _verify_remembered_before_updating_references;
1165 if (_heap->mode()->is_generational() &&
1166 !_heap->old_generation()->is_mark_complete()) {
1167 verify_remembered_set = _verify_remembered_disable;
1168 }
1169 verify_at_safepoint(
1170 generation,
1171 "Before Updating References",
1172 verify_remembered_set, // verify read-write remembered set
1173 _verify_forwarded_allow, // forwarded references allowed
1174 _verify_marked_complete, // bitmaps might be stale, but alloc-after-mark should be well
1175 _verify_cset_forwarded, // all cset refs are fully forwarded
1176 _verify_liveness_disable, // no reliable liveness data anymore
1177 _verify_regions_notrash, // trash regions have been recycled already
1178 _verify_size_exact, // expect generation and heap sizes to match exactly
1179 _verify_gcstate_updating // evacuation should have produced some forwarded objects
1180 );
1181 }
1182
1183 // We have not yet cleanup (reclaimed) the collection set
1184 void ShenandoahVerifier::verify_after_update_refs(ShenandoahGeneration* generation) {
1185 verify_at_safepoint(
1186 generation,
1187 "After Updating References",
1188 _verify_remembered_disable, // do not verify remembered set
1189 _verify_forwarded_none, // no forwarded references
1190 _verify_marked_complete, // bitmaps might be stale, but alloc-after-mark should be well
1191 _verify_cset_none, // no cset references, all updated
1192 _verify_liveness_disable, // no reliable liveness data anymore
1193 _verify_regions_nocset, // no cset regions, trash regions have appeared
1194 // expect generation and heap sizes to match exactly, including trash
1195 _verify_size_exact_including_trash,
1196 _verify_gcstate_stable // update refs had cleaned up forwarded objects
1197 );
1198 }
1199
1200 void ShenandoahVerifier::verify_after_degenerated(ShenandoahGeneration* generation) {
1201 verify_at_safepoint(
1202 generation,
1203 "After Degenerated GC",
1204 _verify_remembered_disable, // do not verify remembered set
1205 _verify_forwarded_none, // all objects are non-forwarded
1206 _verify_marked_complete, // all objects are marked in complete bitmap
1207 _verify_cset_none, // no cset references
1208 _verify_liveness_disable, // no reliable liveness data anymore
1209 _verify_regions_notrash_nocset, // no trash, no cset
1210 _verify_size_exact, // expect generation and heap sizes to match exactly
1211 _verify_gcstate_stable // degenerated refs had cleaned up forwarded objects
1212 );
1213 }
1214
1215 void ShenandoahVerifier::verify_before_fullgc(ShenandoahGeneration* generation) {
1216 verify_at_safepoint(
1217 generation,
1218 "Before Full GC",
1219 _verify_remembered_disable, // do not verify remembered set
1220 _verify_forwarded_allow, // can have forwarded objects
1221 _verify_marked_disable, // do not verify marked: lots ot time wasted checking dead allocations
1222 _verify_cset_disable, // cset might be foobared
1223 _verify_liveness_disable, // no reliable liveness data anymore
1224 _verify_regions_disable, // no reliable region data here
1225 _verify_size_disable, // if we degenerate during evacuation, usage not valid: padding and deferred accounting
1226 _verify_gcstate_disable // no reliable gcstate data
1227 );
1228 }
1229
1230 void ShenandoahVerifier::verify_after_fullgc(ShenandoahGeneration* generation) {
1231 verify_at_safepoint(
1232 generation,
1233 "After Full GC",
1234 _verify_remembered_after_full_gc, // verify read-write remembered set
1235 _verify_forwarded_none, // all objects are non-forwarded
1236 _verify_marked_incomplete, // all objects are marked in incomplete bitmap
1237 _verify_cset_none, // no cset references
1238 _verify_liveness_disable, // no reliable liveness data anymore
1239 _verify_regions_notrash_nocset, // no trash, no cset
1240 _verify_size_exact, // expect generation and heap sizes to match exactly
1241 _verify_gcstate_stable // full gc cleaned up everything
1242 );
1243 }
1244
1245 class ShenandoahVerifyNoForwarded : public BasicOopIterateClosure {
1246 private:
1247 template <class T>
1248 void do_oop_work(T* p) {
1249 T o = RawAccess<>::oop_load(p);
1250 if (!CompressedOops::is_null(o)) {
1251 oop obj = CompressedOops::decode_raw_not_null(o);
1252 ShenandoahAsserts::assert_correct(p, obj, __FILE__, __LINE__);
1253
1254 oop fwd = ShenandoahForwarding::get_forwardee_raw_unchecked(obj);
1255 if (obj != fwd) {
1256 ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, p, nullptr,
1257 "Verify Roots", "Should not be forwarded", __FILE__, __LINE__);
1258 }
1259 }
1260 }
1261
1262 public:
1263 void do_oop(narrowOop* p) { do_oop_work(p); }
1264 void do_oop(oop* p) { do_oop_work(p); }
1265 };
1266
1267 class ShenandoahVerifyInToSpaceClosure : public BasicOopIterateClosure {
1268 private:
1269 template <class T>
1270 void do_oop_work(T* p) {
1271 T o = RawAccess<>::oop_load(p);
1272 if (!CompressedOops::is_null(o)) {
1273 oop obj = CompressedOops::decode_raw_not_null(o);
1274 ShenandoahAsserts::assert_correct(p, obj, __FILE__, __LINE__);
1275
1276 ShenandoahHeap* heap = ShenandoahHeap::heap();
1277
1278 if (!heap->marking_context()->is_marked_or_old(obj)) {
1279 ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, p, nullptr,
1280 "Verify Roots In To-Space", "Should be marked", __FILE__, __LINE__);
1281 }
1282
1283 if (heap->in_collection_set(obj)) {
1284 ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, p, nullptr,
1285 "Verify Roots In To-Space", "Should not be in collection set", __FILE__, __LINE__);
1286 }
1287
1288 oop fwd = ShenandoahForwarding::get_forwardee_raw_unchecked(obj);
1289 if (obj != fwd) {
1290 ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, p, nullptr,
1291 "Verify Roots In To-Space", "Should not be forwarded", __FILE__, __LINE__);
1292 }
1293 }
1294 }
1295
1296 public:
1297 void do_oop(narrowOop* p) override { do_oop_work(p); }
1298 void do_oop(oop* p) override { do_oop_work(p); }
1299 };
1300
1301 void ShenandoahVerifier::verify_roots_in_to_space(ShenandoahGeneration* generation) {
1302 ShenandoahVerifyInToSpaceClosure cl;
1303 ShenandoahRootVerifier::roots_do(&cl, generation);
1304 }
1305
1306 void ShenandoahVerifier::verify_roots_no_forwarded(ShenandoahGeneration* generation) {
1307 ShenandoahVerifyNoForwarded cl;
1308 ShenandoahRootVerifier::roots_do(&cl, generation);
1309 }
1310
1311 template<typename Scanner>
1312 class ShenandoahVerifyRemSetClosure : public BasicOopIterateClosure {
1313 protected:
1314 ShenandoahGenerationalHeap* const _heap;
1315 Scanner* const _scanner;
1316 const char* _message;
1317
1318 public:
1319 // Argument distinguishes between initial mark or start of update refs verification.
1320 explicit ShenandoahVerifyRemSetClosure(Scanner* scanner, const char* message) :
1321 _heap(ShenandoahGenerationalHeap::heap()),
1322 _scanner(scanner),
1323 _message(message) {}
1324
1325 template<class T>
1326 inline void work(T* p) {
1327 T o = RawAccess<>::oop_load(p);
1328 if (!CompressedOops::is_null(o)) {
1329 oop obj = CompressedOops::decode_raw_not_null(o);
1330 ShenandoahAsserts::assert_correct(p, obj, __FILE__, __LINE__);
1331
1332 if (_heap->is_in_young(obj) && !_scanner->is_card_dirty((HeapWord*) p)) {
1333 ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, p, nullptr,
1334 _message, "clean card, it should be dirty.", __FILE__, __LINE__);
1335 }
1336 }
1337 }
1338
1339 void do_oop(narrowOop* p) override { work(p); }
1340 void do_oop(oop* p) override { work(p); }
1341 };
1342
1343 template<typename Scanner>
1344 void ShenandoahVerifier::help_verify_region_rem_set(Scanner* scanner, ShenandoahHeapRegion* r,
1345 HeapWord* registration_watermark, const char* message) {
1346 ShenandoahOldGeneration* old_gen = _heap->old_generation();
1347 assert(old_gen->is_mark_complete() || old_gen->is_parsable(), "Sanity");
1348
1349 ShenandoahMarkingContext* ctx = old_gen->is_mark_complete() ? old_gen->complete_marking_context() : nullptr;
1350 ShenandoahVerifyRemSetClosure<Scanner> check_interesting_pointers(scanner, message);
1351 HeapWord* from = r->bottom();
1352 HeapWord* obj_addr = from;
1353 if (r->is_humongous_start()) {
1354 oop obj = cast_to_oop(obj_addr);
1355 if ((ctx == nullptr) || ctx->is_marked(obj)) {
1356 // For humongous objects, the typical object is an array, so the following checks may be overkill
1357 // For regular objects (not object arrays), if the card holding the start of the object is dirty,
1358 // we do not need to verify that cards spanning interesting pointers within this object are dirty.
1359 if (!scanner->is_card_dirty(obj_addr) || obj->is_objArray()) {
1360 obj->oop_iterate(&check_interesting_pointers);
1361 }
1362 // else, object's start is marked dirty and obj is not an objArray, so any interesting pointers are covered
1363 }
1364 // else, this humongous object is not live so no need to verify its internal pointers
1365
1366 if ((obj_addr < registration_watermark) && !scanner->verify_registration(obj_addr, ctx)) {
1367 ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, obj_addr, nullptr, message,
1368 "object not properly registered", __FILE__, __LINE__);
1369 }
1370 } else if (!r->is_humongous()) {
1371 HeapWord* top = r->top();
1372 while (obj_addr < top) {
1373 oop obj = cast_to_oop(obj_addr);
1374 // ctx->is_marked() returns true if mark bit set or if obj above TAMS.
1375 if ((ctx == nullptr) || ctx->is_marked(obj)) {
1376 // For regular objects (not object arrays), if the card holding the start of the object is dirty,
1377 // we do not need to verify that cards spanning interesting pointers within this object are dirty.
1378 if (!scanner->is_card_dirty(obj_addr) || obj->is_objArray()) {
1379 obj->oop_iterate(&check_interesting_pointers);
1380 }
1381 // else, object's start is marked dirty and obj is not an objArray, so any interesting pointers are covered
1382
1383 if ((obj_addr < registration_watermark) && !scanner->verify_registration(obj_addr, ctx)) {
1384 ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, obj_addr, nullptr, message,
1385 "object not properly registered", __FILE__, __LINE__);
1386 }
1387 obj_addr += obj->size();
1388 } else {
1389 // This object is not live so we don't verify dirty cards contained therein
1390 HeapWord* tams = ctx->top_at_mark_start(r);
1391 obj_addr = ctx->get_next_marked_addr(obj_addr, tams);
1392 }
1393 }
1394 }
1395 }
1396
1397 class ShenandoahWriteTableScanner {
1398 private:
1399 ShenandoahScanRemembered* _scanner;
1400 public:
1401 explicit ShenandoahWriteTableScanner(ShenandoahScanRemembered* scanner) : _scanner(scanner) {}
1402
1403 bool is_card_dirty(HeapWord* obj_addr) {
1404 return _scanner->is_write_card_dirty(obj_addr);
1405 }
1406
1407 bool verify_registration(HeapWord* obj_addr, ShenandoahMarkingContext* ctx) {
1408 return _scanner->verify_registration(obj_addr, ctx);
1409 }
1410 };
1411
1412 // Assure that the remember set has a dirty card everywhere there is an interesting pointer.
1413 // This examines the read_card_table between bottom() and top() since all PLABS are retired
1414 // before the safepoint for init_mark. Actually, we retire them before update-references and don't
1415 // restore them until the start of evacuation.
1416 void ShenandoahVerifier::verify_rem_set_before_mark() {
1417 shenandoah_assert_safepoint();
1418 shenandoah_assert_generational();
1419
1420 ShenandoahOldGeneration* old_generation = _heap->old_generation();
1421
1422 log_debug(gc)("Verifying remembered set at %s mark", old_generation->is_doing_mixed_evacuations() ? "mixed" : "young");
1423
1424 ShenandoahScanRemembered* scanner = old_generation->card_scan();
1425 for (size_t i = 0, n = _heap->num_regions(); i < n; ++i) {
1426 ShenandoahHeapRegion* r = _heap->get_region(i);
1427 if (r->is_old() && r->is_active()) {
1428 help_verify_region_rem_set(scanner, r, r->end(), "Verify init-mark remembered set violation");
1429 }
1430 }
1431 }
1432
1433 void ShenandoahVerifier::verify_rem_set_after_full_gc() {
1434 shenandoah_assert_safepoint();
1435 shenandoah_assert_generational();
1436
1437 ShenandoahWriteTableScanner scanner(ShenandoahGenerationalHeap::heap()->old_generation()->card_scan());
1438 for (size_t i = 0, n = _heap->num_regions(); i < n; ++i) {
1439 ShenandoahHeapRegion* r = _heap->get_region(i);
1440 if (r->is_old() && !r->is_cset()) {
1441 help_verify_region_rem_set(&scanner, r, r->top(), "Remembered set violation at end of Full GC");
1442 }
1443 }
1444 }
1445
1446 // Assure that the remember set has a dirty card everywhere there is an interesting pointer. Even though
1447 // the update-references scan of remembered set only examines cards up to update_watermark, the remembered
1448 // set should be valid through top. This examines the write_card_table between bottom() and top() because
1449 // all PLABS are retired immediately before the start of update refs.
1450 void ShenandoahVerifier::verify_rem_set_before_update_ref() {
1451 shenandoah_assert_safepoint();
1452 shenandoah_assert_generational();
1453
1454 ShenandoahWriteTableScanner scanner(_heap->old_generation()->card_scan());
1455 for (size_t i = 0, n = _heap->num_regions(); i < n; ++i) {
1456 ShenandoahHeapRegion* r = _heap->get_region(i);
1457 if (r->is_old() && !r->is_cset()) {
1458 help_verify_region_rem_set(&scanner, r, r->get_update_watermark(), "Remembered set violation at init-update-references");
1459 }
1460 }
1461 }
1462
1463 void ShenandoahVerifier::verify_before_rebuilding_free_set() {
1464 ShenandoahGenerationStatsClosure cl;
1465 _heap->heap_region_iterate(&cl);
1466
1467 ShenandoahGenerationStatsClosure::validate_usage(false, true, "Before free set rebuild", _heap->old_generation(), cl._old);
1468 ShenandoahGenerationStatsClosure::validate_usage(false, true, "Before free set rebuild", _heap->young_generation(), cl._young);
1469 ShenandoahGenerationStatsClosure::validate_usage(false, true, "Before free set rebuild", _heap->global_generation(), cl._global);
1470 }