1 /*
  2  * Copyright (c) 2017, 2021, Red Hat, Inc. 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 "gc/shared/tlab_globals.hpp"
 27 #include "gc/shenandoah/shenandoahAsserts.hpp"
 28 #include "gc/shenandoah/shenandoahForwarding.inline.hpp"
 29 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
 30 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
 31 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
 32 #include "gc/shenandoah/shenandoahObjectUtils.inline.hpp"
 33 #include "gc/shenandoah/shenandoahRootProcessor.hpp"
 34 #include "gc/shenandoah/shenandoahTaskqueue.inline.hpp"
 35 #include "gc/shenandoah/shenandoahUtils.hpp"
 36 #include "gc/shenandoah/shenandoahVerifier.hpp"
 37 #include "memory/allocation.hpp"
 38 #include "memory/iterator.inline.hpp"
 39 #include "memory/resourceArea.hpp"
 40 #include "oops/compressedOops.inline.hpp"
 41 #include "runtime/atomic.hpp"
 42 #include "runtime/orderAccess.hpp"
 43 #include "runtime/threads.hpp"
 44 #include "utilities/align.hpp"
 45 
 46 // Avoid name collision on verify_oop (defined in macroAssembler_arm.hpp)
 47 #ifdef verify_oop
 48 #undef verify_oop
 49 #endif
 50 
 51 static bool is_instance_ref_klass(Klass* k) {
 52   return k->is_instance_klass() && InstanceKlass::cast(k)->reference_type() != REF_NONE;
 53 }
 54 
 55 class ShenandoahIgnoreReferenceDiscoverer : public ReferenceDiscoverer {
 56 public:
 57   virtual bool discover_reference(oop obj, ReferenceType type) {
 58     return true;
 59   }
 60 };
 61 
 62 class ShenandoahVerifyOopClosure : public BasicOopIterateClosure {
 63 private:
 64   const char* _phase;
 65   ShenandoahVerifier::VerifyOptions _options;
 66   ShenandoahVerifierStack* _stack;
 67   ShenandoahHeap* _heap;
 68   MarkBitMap* _map;
 69   ShenandoahLivenessData* _ld;
 70   void* _interior_loc;
 71   oop _loc;
 72 
 73 public:
 74   ShenandoahVerifyOopClosure(ShenandoahVerifierStack* stack, 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(NULL),
 83     _loc(NULL) {
 84     if (options._verify_marked == ShenandoahVerifier::_verify_marked_complete_except_references ||
 85         options._verify_marked == ShenandoahVerifier::_verify_marked_disable) {
 86       set_ref_discoverer_internal(new ShenandoahIgnoreReferenceDiscoverer());
 87     }
 88   }
 89 
 90 private:
 91   void check(ShenandoahAsserts::SafeLevel level, oop obj, bool test, const char* label) {
 92     if (!test) {
 93       ShenandoahAsserts::print_failure(level, obj, _interior_loc, _loc, _phase, label, __FILE__, __LINE__);
 94     }
 95   }
 96 
 97   template <class T>
 98   void do_oop_work(T* p) {
 99     T o = RawAccess<>::oop_load(p);
100     if (!CompressedOops::is_null(o)) {
101       oop obj = CompressedOops::decode_not_null(o);
102       if (is_instance_ref_klass(ShenandoahObjectUtils::klass(obj))) {
103         obj = ShenandoahForwarding::get_forwardee(obj);
104       }
105       // Single threaded verification can use faster non-atomic stack and bitmap
106       // methods.
107       //
108       // For performance reasons, only fully verify non-marked field values.
109       // We are here when the host object for *p is already marked.
110 
111       if (_map->par_mark(obj)) {
112         verify_oop_at(p, obj);
113         _stack->push(ShenandoahVerifierTask(obj));
114       }
115     }
116   }
117 
118   void verify_oop(oop obj) {
119     // Perform consistency checks with gradually decreasing safety level. This guarantees
120     // that failure report would not try to touch something that was not yet verified to be
121     // safe to process.
122 
123     check(ShenandoahAsserts::_safe_unknown, obj, _heap->is_in(obj),
124               "oop must be in heap");
125     check(ShenandoahAsserts::_safe_unknown, obj, is_object_aligned(obj),
126               "oop must be aligned");
127 
128     ShenandoahHeapRegion *obj_reg = _heap->heap_region_containing(obj);
129     Klass* obj_klass = ShenandoahObjectUtils::klass(obj);
130 
131     // Verify that obj is not in dead space:
132     {
133       // Do this before touching obj->size()
134       check(ShenandoahAsserts::_safe_unknown, obj, obj_klass != NULL,
135              "Object klass pointer should not be NULL");
136       check(ShenandoahAsserts::_safe_unknown, obj, Metaspace::contains(obj_klass),
137              "Object klass pointer must go to metaspace");
138 
139       HeapWord *obj_addr = cast_from_oop<HeapWord*>(obj);
140       check(ShenandoahAsserts::_safe_unknown, obj, obj_addr < obj_reg->top(),
141              "Object start should be within the region");
142 
143       if (!obj_reg->is_humongous()) {
144         check(ShenandoahAsserts::_safe_unknown, obj, (obj_addr + ShenandoahObjectUtils::size(obj)) <= obj_reg->top(),
145                "Object end should be within the region");
146       } else {
147         size_t humongous_start = obj_reg->index();
148         size_t humongous_end = humongous_start + (ShenandoahObjectUtils::size(obj) >> ShenandoahHeapRegion::region_size_words_shift());
149         for (size_t idx = humongous_start + 1; idx < humongous_end; idx++) {
150           check(ShenandoahAsserts::_safe_unknown, obj, _heap->get_region(idx)->is_humongous_continuation(),
151                  "Humongous object is in continuation that fits it");
152         }
153       }
154 
155       // ------------ obj is safe at this point --------------
156 
157       check(ShenandoahAsserts::_safe_oop, obj, obj_reg->is_active(),
158             "Object should be in active region");
159 
160       switch (_options._verify_liveness) {
161         case ShenandoahVerifier::_verify_liveness_disable:
162           // skip
163           break;
164         case ShenandoahVerifier::_verify_liveness_complete:
165           Atomic::add(&_ld[obj_reg->index()], (uint) ShenandoahObjectUtils::size(obj), memory_order_relaxed);
166           // fallthrough for fast failure for un-live regions:
167         case ShenandoahVerifier::_verify_liveness_conservative:
168           check(ShenandoahAsserts::_safe_oop, obj, obj_reg->has_live(),
169                    "Object must belong to region with live data");
170           break;
171         default:
172           assert(false, "Unhandled liveness verification");
173       }
174     }
175 
176     oop fwd = ShenandoahForwarding::get_forwardee_raw_unchecked(obj);
177 
178     ShenandoahHeapRegion* fwd_reg = NULL;
179 
180     if (obj != fwd) {
181       check(ShenandoahAsserts::_safe_oop, obj, _heap->is_in(fwd),
182              "Forwardee must be in heap");
183       check(ShenandoahAsserts::_safe_oop, obj, !CompressedOops::is_null(fwd),
184              "Forwardee is set");
185       check(ShenandoahAsserts::_safe_oop, obj, is_object_aligned(fwd),
186              "Forwardee must be aligned");
187 
188       // Do this before touching fwd->size()
189       Klass* fwd_klass = fwd->klass_or_null();
190       check(ShenandoahAsserts::_safe_oop, obj, fwd_klass != NULL,
191              "Forwardee klass pointer should not be NULL");
192       check(ShenandoahAsserts::_safe_oop, obj, Metaspace::contains(fwd_klass),
193              "Forwardee klass pointer must go to metaspace");
194       check(ShenandoahAsserts::_safe_oop, obj, obj_klass == fwd_klass,
195              "Forwardee klass pointer must go to metaspace");
196 
197       fwd_reg = _heap->heap_region_containing(fwd);
198 
199       // Verify that forwardee is not in the dead space:
200       check(ShenandoahAsserts::_safe_oop, obj, !fwd_reg->is_humongous(),
201              "Should have no humongous forwardees");
202 
203       HeapWord *fwd_addr = cast_from_oop<HeapWord *>(fwd);
204       check(ShenandoahAsserts::_safe_oop, obj, fwd_addr < fwd_reg->top(),
205              "Forwardee start should be within the region");
206       check(ShenandoahAsserts::_safe_oop, obj, (fwd_addr + ShenandoahObjectUtils::size(fwd)) <= fwd_reg->top(),
207              "Forwardee end should be within the region");
208 
209       oop fwd2 = ShenandoahForwarding::get_forwardee_raw_unchecked(fwd);
210       check(ShenandoahAsserts::_safe_oop, obj, (fwd == fwd2),
211              "Double forwarding");
212     } else {
213       fwd_reg = obj_reg;
214     }
215 
216     // ------------ obj and fwd are safe at this point --------------
217 
218     switch (_options._verify_marked) {
219       case ShenandoahVerifier::_verify_marked_disable:
220         // skip
221         break;
222       case ShenandoahVerifier::_verify_marked_incomplete:
223         check(ShenandoahAsserts::_safe_all, obj, _heap->marking_context()->is_marked(obj),
224                "Must be marked in incomplete bitmap");
225         break;
226       case ShenandoahVerifier::_verify_marked_complete:
227         check(ShenandoahAsserts::_safe_all, obj, _heap->complete_marking_context()->is_marked(obj),
228                "Must be marked in complete bitmap");
229         break;
230       case ShenandoahVerifier::_verify_marked_complete_except_references:
231         check(ShenandoahAsserts::_safe_all, obj, _heap->complete_marking_context()->is_marked(obj),
232               "Must be marked in complete bitmap, except j.l.r.Reference referents");
233         break;
234       default:
235         assert(false, "Unhandled mark verification");
236     }
237 
238     switch (_options._verify_forwarded) {
239       case ShenandoahVerifier::_verify_forwarded_disable:
240         // skip
241         break;
242       case ShenandoahVerifier::_verify_forwarded_none: {
243         check(ShenandoahAsserts::_safe_all, obj, (obj == fwd),
244                "Should not be forwarded");
245         break;
246       }
247       case ShenandoahVerifier::_verify_forwarded_allow: {
248         if (obj != fwd) {
249           check(ShenandoahAsserts::_safe_all, obj, obj_reg != fwd_reg,
250                  "Forwardee should be in another region");
251         }
252         break;
253       }
254       default:
255         assert(false, "Unhandled forwarding verification");
256     }
257 
258     switch (_options._verify_cset) {
259       case ShenandoahVerifier::_verify_cset_disable:
260         // skip
261         break;
262       case ShenandoahVerifier::_verify_cset_none:
263         check(ShenandoahAsserts::_safe_all, obj, !_heap->in_collection_set(obj),
264                "Should not have references to collection set");
265         break;
266       case ShenandoahVerifier::_verify_cset_forwarded:
267         if (_heap->in_collection_set(obj)) {
268           check(ShenandoahAsserts::_safe_all, obj, (obj != fwd),
269                  "Object in collection set, should have forwardee");
270         }
271         break;
272       default:
273         assert(false, "Unhandled cset verification");
274     }
275 
276   }
277 
278 public:
279   /**
280    * Verify object with known interior reference.
281    * @param p interior reference where the object is referenced from; can be off-heap
282    * @param obj verified object
283    */
284   template <class T>
285   void verify_oop_at(T* p, oop obj) {
286     _interior_loc = p;
287     verify_oop(obj);
288     _interior_loc = NULL;
289   }
290 
291   /**
292    * Verify object without known interior reference.
293    * Useful when picking up the object at known offset in heap,
294    * but without knowing what objects reference it.
295    * @param obj verified object
296    */
297   void verify_oop_standalone(oop obj) {
298     _interior_loc = NULL;
299     verify_oop(obj);
300     _interior_loc = NULL;
301   }
302 
303   /**
304    * Verify oop fields from this object.
305    * @param obj host object for verified fields
306    */
307   void verify_oops_from(oop obj) {
308     _loc = obj;
309     Klass* klass = ShenandoahObjectUtils::klass(obj);
310     obj->oop_iterate_backwards(this, klass);
311     _loc = NULL;
312   }
313 
314   virtual void do_oop(oop* p) { do_oop_work(p); }
315   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
316 };
317 
318 class ShenandoahCalculateRegionStatsClosure : public ShenandoahHeapRegionClosure {
319 private:
320   size_t _used, _committed, _garbage;
321 public:
322   ShenandoahCalculateRegionStatsClosure() : _used(0), _committed(0), _garbage(0) {};
323 
324   void heap_region_do(ShenandoahHeapRegion* r) {
325     _used += r->used();
326     _garbage += r->garbage();
327     _committed += r->is_committed() ? ShenandoahHeapRegion::region_size_bytes() : 0;
328   }
329 
330   size_t used() { return _used; }
331   size_t committed() { return _committed; }
332   size_t garbage() { return _garbage; }
333 };
334 
335 class ShenandoahVerifyHeapRegionClosure : public ShenandoahHeapRegionClosure {
336 private:
337   ShenandoahHeap* _heap;
338   const char* _phase;
339   ShenandoahVerifier::VerifyRegions _regions;
340 public:
341   ShenandoahVerifyHeapRegionClosure(const char* phase, ShenandoahVerifier::VerifyRegions regions) :
342     _heap(ShenandoahHeap::heap()),
343     _phase(phase),
344     _regions(regions) {};
345 
346   void print_failure(ShenandoahHeapRegion* r, const char* label) {
347     ResourceMark rm;
348 
349     ShenandoahMessageBuffer msg("Shenandoah verification failed; %s: %s\n\n", _phase, label);
350 
351     stringStream ss;
352     r->print_on(&ss);
353     msg.append("%s", ss.as_string());
354 
355     report_vm_error(__FILE__, __LINE__, msg.buffer());
356   }
357 
358   void verify(ShenandoahHeapRegion* r, bool test, const char* msg) {
359     if (!test) {
360       print_failure(r, msg);
361     }
362   }
363 
364   void heap_region_do(ShenandoahHeapRegion* r) {
365     switch (_regions) {
366       case ShenandoahVerifier::_verify_regions_disable:
367         break;
368       case ShenandoahVerifier::_verify_regions_notrash:
369         verify(r, !r->is_trash(),
370                "Should not have trash regions");
371         break;
372       case ShenandoahVerifier::_verify_regions_nocset:
373         verify(r, !r->is_cset(),
374                "Should not have cset regions");
375         break;
376       case ShenandoahVerifier::_verify_regions_notrash_nocset:
377         verify(r, !r->is_trash(),
378                "Should not have trash regions");
379         verify(r, !r->is_cset(),
380                "Should not have cset regions");
381         break;
382       default:
383         ShouldNotReachHere();
384     }
385 
386     verify(r, r->capacity() == ShenandoahHeapRegion::region_size_bytes(),
387            "Capacity should match region size");
388 
389     verify(r, r->bottom() <= r->top(),
390            "Region top should not be less than bottom");
391 
392     verify(r, r->bottom() <= _heap->marking_context()->top_at_mark_start(r),
393            "Region TAMS should not be less than bottom");
394 
395     verify(r, _heap->marking_context()->top_at_mark_start(r) <= r->top(),
396            "Complete TAMS should not be larger than top");
397 
398     verify(r, r->get_live_data_bytes() <= r->capacity(),
399            "Live data cannot be larger than capacity");
400 
401     verify(r, r->garbage() <= r->capacity(),
402            "Garbage cannot be larger than capacity");
403 
404     verify(r, r->used() <= r->capacity(),
405            "Used cannot be larger than capacity");
406 
407     verify(r, r->get_shared_allocs() <= r->capacity(),
408            "Shared alloc count should not be larger than capacity");
409 
410     verify(r, r->get_tlab_allocs() <= r->capacity(),
411            "TLAB alloc count should not be larger than capacity");
412 
413     verify(r, r->get_gclab_allocs() <= r->capacity(),
414            "GCLAB alloc count should not be larger than capacity");
415 
416     verify(r, r->get_shared_allocs() + r->get_tlab_allocs() + r->get_gclab_allocs() == r->used(),
417            "Accurate accounting: shared + TLAB + GCLAB = used");
418 
419     verify(r, !r->is_empty() || !r->has_live(),
420            "Empty regions should not have live data");
421 
422     verify(r, r->is_cset() == _heap->collection_set()->is_in(r),
423            "Transitional: region flags and collection set agree");
424   }
425 };
426 
427 class ShenandoahVerifierReachableTask : public WorkerTask {
428 private:
429   const char* _label;
430   ShenandoahVerifier::VerifyOptions _options;
431   ShenandoahHeap* _heap;
432   ShenandoahLivenessData* _ld;
433   MarkBitMap* _bitmap;
434   volatile size_t _processed;
435 
436 public:
437   ShenandoahVerifierReachableTask(MarkBitMap* bitmap,
438                                   ShenandoahLivenessData* ld,
439                                   const char* label,
440                                   ShenandoahVerifier::VerifyOptions options) :
441     WorkerTask("Shenandoah Verifier Reachable Objects"),
442     _label(label),
443     _options(options),
444     _heap(ShenandoahHeap::heap()),
445     _ld(ld),
446     _bitmap(bitmap),
447     _processed(0) {};
448 
449   size_t processed() {
450     return _processed;
451   }
452 
453   virtual void work(uint worker_id) {
454     ResourceMark rm;
455     ShenandoahVerifierStack stack;
456 
457     // On level 2, we need to only check the roots once.
458     // On level 3, we want to check the roots, and seed the local stack.
459     // It is a lesser evil to accept multiple root scans at level 3, because
460     // extended parallelism would buy us out.
461     if (((ShenandoahVerifyLevel == 2) && (worker_id == 0))
462         || (ShenandoahVerifyLevel >= 3)) {
463         ShenandoahVerifyOopClosure cl(&stack, _bitmap, _ld,
464                                       ShenandoahMessageBuffer("%s, Roots", _label),
465                                       _options);
466         if (_heap->unload_classes()) {
467           ShenandoahRootVerifier::strong_roots_do(&cl);
468         } else {
469           ShenandoahRootVerifier::roots_do(&cl);
470         }
471     }
472 
473     size_t processed = 0;
474 
475     if (ShenandoahVerifyLevel >= 3) {
476       ShenandoahVerifyOopClosure cl(&stack, _bitmap, _ld,
477                                     ShenandoahMessageBuffer("%s, Reachable", _label),
478                                     _options);
479       while (!stack.is_empty()) {
480         processed++;
481         ShenandoahVerifierTask task = stack.pop();
482         cl.verify_oops_from(task.obj());
483       }
484     }
485 
486     Atomic::add(&_processed, processed, memory_order_relaxed);
487   }
488 };
489 
490 class ShenandoahVerifierMarkedRegionTask : public WorkerTask {
491 private:
492   const char* _label;
493   ShenandoahVerifier::VerifyOptions _options;
494   ShenandoahHeap *_heap;
495   MarkBitMap* _bitmap;
496   ShenandoahLivenessData* _ld;
497   volatile size_t _claimed;
498   volatile size_t _processed;
499 
500 public:
501   ShenandoahVerifierMarkedRegionTask(MarkBitMap* bitmap,
502                                      ShenandoahLivenessData* ld,
503                                      const char* label,
504                                      ShenandoahVerifier::VerifyOptions options) :
505           WorkerTask("Shenandoah Verifier Marked Objects"),
506           _label(label),
507           _options(options),
508           _heap(ShenandoahHeap::heap()),
509           _bitmap(bitmap),
510           _ld(ld),
511           _claimed(0),
512           _processed(0) {};
513 
514   size_t processed() {
515     return Atomic::load(&_processed);
516   }
517 
518   virtual void work(uint worker_id) {
519     ShenandoahVerifierStack stack;
520     ShenandoahVerifyOopClosure cl(&stack, _bitmap, _ld,
521                                   ShenandoahMessageBuffer("%s, Marked", _label),
522                                   _options);
523 
524     while (true) {
525       size_t v = Atomic::fetch_and_add(&_claimed, 1u, memory_order_relaxed);
526       if (v < _heap->num_regions()) {
527         ShenandoahHeapRegion* r = _heap->get_region(v);
528         if (!r->is_humongous() && !r->is_trash()) {
529           work_regular(r, stack, cl);
530         } else if (r->is_humongous_start()) {
531           work_humongous(r, stack, cl);
532         }
533       } else {
534         break;
535       }
536     }
537   }
538 
539   virtual void work_humongous(ShenandoahHeapRegion *r, ShenandoahVerifierStack& stack, ShenandoahVerifyOopClosure& cl) {
540     size_t processed = 0;
541     HeapWord* obj = r->bottom();
542     if (_heap->complete_marking_context()->is_marked(cast_to_oop(obj))) {
543       verify_and_follow(obj, stack, cl, &processed);
544     }
545     Atomic::add(&_processed, processed, memory_order_relaxed);
546   }
547 
548   virtual void work_regular(ShenandoahHeapRegion *r, ShenandoahVerifierStack &stack, ShenandoahVerifyOopClosure &cl) {
549     size_t processed = 0;
550     ShenandoahMarkingContext* ctx = _heap->complete_marking_context();
551     HeapWord* tams = ctx->top_at_mark_start(r);
552 
553     // Bitmaps, before TAMS
554     if (tams > r->bottom()) {
555       HeapWord* start = r->bottom();
556       HeapWord* addr = ctx->get_next_marked_addr(start, tams);
557 
558       while (addr < tams) {
559         verify_and_follow(addr, stack, cl, &processed);
560         addr += 1;
561         if (addr < tams) {
562           addr = ctx->get_next_marked_addr(addr, tams);
563         }
564       }
565     }
566 
567     // Size-based, after TAMS
568     {
569       HeapWord* limit = r->top();
570       HeapWord* addr = tams;
571 
572       while (addr < limit) {
573         verify_and_follow(addr, stack, cl, &processed);
574         addr += cast_to_oop(addr)->size();
575       }
576     }
577 
578     Atomic::add(&_processed, processed, memory_order_relaxed);
579   }
580 
581   void verify_and_follow(HeapWord *addr, ShenandoahVerifierStack &stack, ShenandoahVerifyOopClosure &cl, size_t *processed) {
582     if (!_bitmap->par_mark(addr)) return;
583 
584     // Verify the object itself:
585     oop obj = cast_to_oop(addr);
586     cl.verify_oop_standalone(obj);
587 
588     // Verify everything reachable from that object too, hopefully realizing
589     // everything was already marked, and never touching further:
590     if (!is_instance_ref_klass(ShenandoahObjectUtils::klass(obj))) {
591       cl.verify_oops_from(obj);
592       (*processed)++;
593     }
594     while (!stack.is_empty()) {
595       ShenandoahVerifierTask task = stack.pop();
596       cl.verify_oops_from(task.obj());
597       (*processed)++;
598     }
599   }
600 };
601 
602 class VerifyThreadGCState : public ThreadClosure {
603 private:
604   const char* const _label;
605          char const _expected;
606 
607 public:
608   VerifyThreadGCState(const char* label, char expected) : _label(label), _expected(expected) {}
609   void do_thread(Thread* t) {
610     char actual = ShenandoahThreadLocalData::gc_state(t);
611     if (actual != _expected) {
612       fatal("%s: Thread %s: expected gc-state %d, actual %d", _label, t->name(), _expected, actual);
613     }
614   }
615 };
616 
617 void ShenandoahVerifier::verify_at_safepoint(const char *label,
618                                              VerifyForwarded forwarded, VerifyMarked marked,
619                                              VerifyCollectionSet cset,
620                                              VerifyLiveness liveness, VerifyRegions regions,
621                                              VerifyGCState gcstate) {
622   guarantee(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "only when nothing else happens");
623   guarantee(ShenandoahVerify, "only when enabled, and bitmap is initialized in ShenandoahHeap::initialize");
624 
625   // Avoid side-effect of changing workers' active thread count, but bypass concurrent/parallel protocol check
626   ShenandoahPushWorkerScope verify_worker_scope(_heap->workers(), _heap->max_workers(), false /*bypass check*/);
627 
628   log_info(gc,start)("Verify %s, Level " INTX_FORMAT, label, ShenandoahVerifyLevel);
629 
630   // GC state checks
631   {
632     char expected = -1;
633     bool enabled;
634     switch (gcstate) {
635       case _verify_gcstate_disable:
636         enabled = false;
637         break;
638       case _verify_gcstate_forwarded:
639         enabled = true;
640         expected = ShenandoahHeap::HAS_FORWARDED;
641         break;
642       case _verify_gcstate_evacuation:
643         enabled = true;
644         expected = ShenandoahHeap::HAS_FORWARDED | ShenandoahHeap::EVACUATION;
645         if (!_heap->is_stw_gc_in_progress()) {
646           // Only concurrent GC sets this.
647           expected |= ShenandoahHeap::WEAK_ROOTS;
648         }
649         break;
650       case _verify_gcstate_stable:
651         enabled = true;
652         expected = ShenandoahHeap::STABLE;
653         break;
654       case _verify_gcstate_stable_weakroots:
655         enabled = true;
656         expected = ShenandoahHeap::STABLE;
657         if (!_heap->is_stw_gc_in_progress()) {
658           // Only concurrent GC sets this.
659           expected |= ShenandoahHeap::WEAK_ROOTS;
660         }
661         break;
662       default:
663         enabled = false;
664         assert(false, "Unhandled gc-state verification");
665     }
666 
667     if (enabled) {
668       char actual = _heap->gc_state();
669       if (actual != expected) {
670         fatal("%s: Global gc-state: expected %d, actual %d", label, expected, actual);
671       }
672 
673       VerifyThreadGCState vtgcs(label, expected);
674       Threads::java_threads_do(&vtgcs);
675     }
676   }
677 
678   // Deactivate barriers temporarily: Verifier wants plain heap accesses
679   ShenandoahGCStateResetter resetter;
680 
681   // Heap size checks
682   {
683     ShenandoahHeapLocker lock(_heap->lock());
684 
685     ShenandoahCalculateRegionStatsClosure cl;
686     _heap->heap_region_iterate(&cl);
687     size_t heap_used = _heap->used();
688     guarantee(cl.used() == heap_used,
689               "%s: heap used size must be consistent: heap-used = " SIZE_FORMAT "%s, regions-used = " SIZE_FORMAT "%s",
690               label,
691               byte_size_in_proper_unit(heap_used), proper_unit_for_byte_size(heap_used),
692               byte_size_in_proper_unit(cl.used()), proper_unit_for_byte_size(cl.used()));
693 
694     size_t heap_committed = _heap->committed();
695     guarantee(cl.committed() == heap_committed,
696               "%s: heap committed size must be consistent: heap-committed = " SIZE_FORMAT "%s, regions-committed = " SIZE_FORMAT "%s",
697               label,
698               byte_size_in_proper_unit(heap_committed), proper_unit_for_byte_size(heap_committed),
699               byte_size_in_proper_unit(cl.committed()), proper_unit_for_byte_size(cl.committed()));
700   }
701 
702   // Internal heap region checks
703   if (ShenandoahVerifyLevel >= 1) {
704     ShenandoahVerifyHeapRegionClosure cl(label, regions);
705     _heap->heap_region_iterate(&cl);
706   }
707 
708   OrderAccess::fence();
709 
710   if (UseTLAB) {
711     _heap->labs_make_parsable();
712   }
713 
714   // Allocate temporary bitmap for storing marking wavefront:
715   _verification_bit_map->clear();
716 
717   // Allocate temporary array for storing liveness data
718   ShenandoahLivenessData* ld = NEW_C_HEAP_ARRAY(ShenandoahLivenessData, _heap->num_regions(), mtGC);
719   Copy::fill_to_bytes((void*)ld, _heap->num_regions()*sizeof(ShenandoahLivenessData), 0);
720 
721   const VerifyOptions& options = ShenandoahVerifier::VerifyOptions(forwarded, marked, cset, liveness, regions, gcstate);
722 
723   // Steps 1-2. Scan root set to get initial reachable set. Finish walking the reachable heap.
724   // This verifies what application can see, since it only cares about reachable objects.
725   size_t count_reachable = 0;
726   if (ShenandoahVerifyLevel >= 2) {
727     ShenandoahVerifierReachableTask task(_verification_bit_map, ld, label, options);
728     _heap->workers()->run_task(&task);
729     count_reachable = task.processed();
730   }
731 
732   // Step 3. Walk marked objects. Marked objects might be unreachable. This verifies what collector,
733   // not the application, can see during the region scans. There is no reason to process the objects
734   // that were already verified, e.g. those marked in verification bitmap. There is interaction with TAMS:
735   // before TAMS, we verify the bitmaps, if available; after TAMS, we walk until the top(). It mimics
736   // what marked_object_iterate is doing, without calling into that optimized (and possibly incorrect)
737   // version
738 
739   size_t count_marked = 0;
740   if (ShenandoahVerifyLevel >= 4 && (marked == _verify_marked_complete || marked == _verify_marked_complete_except_references)) {
741     guarantee(_heap->marking_context()->is_complete(), "Marking context should be complete");
742     ShenandoahVerifierMarkedRegionTask task(_verification_bit_map, ld, label, options);
743     _heap->workers()->run_task(&task);
744     count_marked = task.processed();
745   } else {
746     guarantee(ShenandoahVerifyLevel < 4 || marked == _verify_marked_incomplete || marked == _verify_marked_disable, "Should be");
747   }
748 
749   // Step 4. Verify accumulated liveness data, if needed. Only reliable if verification level includes
750   // marked objects.
751 
752   if (ShenandoahVerifyLevel >= 4 && marked == _verify_marked_complete && liveness == _verify_liveness_complete) {
753     for (size_t i = 0; i < _heap->num_regions(); i++) {
754       ShenandoahHeapRegion* r = _heap->get_region(i);
755 
756       juint verf_live = 0;
757       if (r->is_humongous()) {
758         // For humongous objects, test if start region is marked live, and if so,
759         // all humongous regions in that chain have live data equal to their "used".
760         juint start_live = Atomic::load(&ld[r->humongous_start_region()->index()]);
761         if (start_live > 0) {
762           verf_live = (juint)(r->used() / HeapWordSize);
763         }
764       } else {
765         verf_live = Atomic::load(&ld[r->index()]);
766       }
767 
768       size_t reg_live = r->get_live_data_words();
769       if (reg_live != verf_live) {
770         stringStream ss;
771         r->print_on(&ss);
772         fatal("%s: Live data should match: region-live = " SIZE_FORMAT ", verifier-live = " UINT32_FORMAT "\n%s",
773               label, reg_live, verf_live, ss.freeze());
774       }
775     }
776   }
777 
778   log_info(gc)("Verify %s, Level " INTX_FORMAT " (" SIZE_FORMAT " reachable, " SIZE_FORMAT " marked)",
779                label, ShenandoahVerifyLevel, count_reachable, count_marked);
780 
781   FREE_C_HEAP_ARRAY(ShenandoahLivenessData, ld);
782 }
783 
784 void ShenandoahVerifier::verify_generic(VerifyOption vo) {
785   verify_at_safepoint(
786           "Generic Verification",
787           _verify_forwarded_allow,     // conservatively allow forwarded
788           _verify_marked_disable,      // do not verify marked: lots ot time wasted checking dead allocations
789           _verify_cset_disable,        // cset may be inconsistent
790           _verify_liveness_disable,    // no reliable liveness data
791           _verify_regions_disable,     // no reliable region data
792           _verify_gcstate_disable      // no data about gcstate
793   );
794 }
795 
796 void ShenandoahVerifier::verify_before_concmark() {
797     verify_at_safepoint(
798           "Before Mark",
799           _verify_forwarded_none,      // UR should have fixed up
800           _verify_marked_disable,      // do not verify marked: lots ot time wasted checking dead allocations
801           _verify_cset_none,           // UR should have fixed this
802           _verify_liveness_disable,    // no reliable liveness data
803           _verify_regions_notrash,     // no trash regions
804           _verify_gcstate_stable       // there are no forwarded objects
805   );
806 }
807 
808 void ShenandoahVerifier::verify_after_concmark() {
809   verify_at_safepoint(
810           "After Mark",
811           _verify_forwarded_none,      // no forwarded references
812           _verify_marked_complete_except_references, // bitmaps as precise as we can get, except dangling j.l.r.Refs
813           _verify_cset_none,           // no references to cset anymore
814           _verify_liveness_complete,   // liveness data must be complete here
815           _verify_regions_disable,     // trash regions not yet recycled
816           _verify_gcstate_stable_weakroots  // heap is still stable, weakroots are in progress
817   );
818 }
819 
820 void ShenandoahVerifier::verify_before_evacuation() {
821   verify_at_safepoint(
822           "Before Evacuation",
823           _verify_forwarded_none,                    // no forwarded references
824           _verify_marked_complete_except_references, // walk over marked objects too
825           _verify_cset_disable,                      // non-forwarded references to cset expected
826           _verify_liveness_complete,                 // liveness data must be complete here
827           _verify_regions_disable,                   // trash regions not yet recycled
828           _verify_gcstate_stable_weakroots           // heap is still stable, weakroots are in progress
829   );
830 }
831 
832 void ShenandoahVerifier::verify_during_evacuation() {
833   verify_at_safepoint(
834           "During Evacuation",
835           _verify_forwarded_allow,    // some forwarded references are allowed
836           _verify_marked_disable,     // walk only roots
837           _verify_cset_disable,       // some cset references are not forwarded yet
838           _verify_liveness_disable,   // liveness data might be already stale after pre-evacs
839           _verify_regions_disable,    // trash regions not yet recycled
840           _verify_gcstate_evacuation  // evacuation is in progress
841   );
842 }
843 
844 void ShenandoahVerifier::verify_after_evacuation() {
845   verify_at_safepoint(
846           "After Evacuation",
847           _verify_forwarded_allow,     // objects are still forwarded
848           _verify_marked_complete,     // bitmaps might be stale, but alloc-after-mark should be well
849           _verify_cset_forwarded,      // all cset refs are fully forwarded
850           _verify_liveness_disable,    // no reliable liveness data anymore
851           _verify_regions_notrash,     // trash regions have been recycled already
852           _verify_gcstate_forwarded    // evacuation produced some forwarded objects
853   );
854 }
855 
856 void ShenandoahVerifier::verify_before_updaterefs() {
857   verify_at_safepoint(
858           "Before Updating References",
859           _verify_forwarded_allow,     // forwarded references allowed
860           _verify_marked_complete,     // bitmaps might be stale, but alloc-after-mark should be well
861           _verify_cset_forwarded,      // all cset refs are fully forwarded
862           _verify_liveness_disable,    // no reliable liveness data anymore
863           _verify_regions_notrash,     // trash regions have been recycled already
864           _verify_gcstate_forwarded    // evacuation should have produced some forwarded objects
865   );
866 }
867 
868 void ShenandoahVerifier::verify_after_updaterefs() {
869   verify_at_safepoint(
870           "After Updating References",
871           _verify_forwarded_none,      // no forwarded references
872           _verify_marked_complete,     // bitmaps might be stale, but alloc-after-mark should be well
873           _verify_cset_none,           // no cset references, all updated
874           _verify_liveness_disable,    // no reliable liveness data anymore
875           _verify_regions_nocset,      // no cset regions, trash regions have appeared
876           _verify_gcstate_stable       // update refs had cleaned up forwarded objects
877   );
878 }
879 
880 void ShenandoahVerifier::verify_after_degenerated() {
881   verify_at_safepoint(
882           "After Degenerated GC",
883           _verify_forwarded_none,      // all objects are non-forwarded
884           _verify_marked_complete,     // all objects are marked in complete bitmap
885           _verify_cset_none,           // no cset references
886           _verify_liveness_disable,    // no reliable liveness data anymore
887           _verify_regions_notrash_nocset, // no trash, no cset
888           _verify_gcstate_stable       // degenerated refs had cleaned up forwarded objects
889   );
890 }
891 
892 void ShenandoahVerifier::verify_before_fullgc() {
893   verify_at_safepoint(
894           "Before Full GC",
895           _verify_forwarded_allow,     // can have forwarded objects
896           _verify_marked_disable,      // do not verify marked: lots ot time wasted checking dead allocations
897           _verify_cset_disable,        // cset might be foobared
898           _verify_liveness_disable,    // no reliable liveness data anymore
899           _verify_regions_disable,     // no reliable region data here
900           _verify_gcstate_disable      // no reliable gcstate data
901   );
902 }
903 
904 void ShenandoahVerifier::verify_after_fullgc() {
905   verify_at_safepoint(
906           "After Full GC",
907           _verify_forwarded_none,      // all objects are non-forwarded
908           _verify_marked_complete,     // all objects are marked in complete bitmap
909           _verify_cset_none,           // no cset references
910           _verify_liveness_disable,    // no reliable liveness data anymore
911           _verify_regions_notrash_nocset, // no trash, no cset
912           _verify_gcstate_stable        // full gc cleaned up everything
913   );
914 }
915 
916 class ShenandoahVerifyNoForwared : public OopClosure {
917 private:
918   template <class T>
919   void do_oop_work(T* p) {
920     T o = RawAccess<>::oop_load(p);
921     if (!CompressedOops::is_null(o)) {
922       oop obj = CompressedOops::decode_not_null(o);
923       oop fwd = ShenandoahForwarding::get_forwardee_raw_unchecked(obj);
924       if (obj != fwd) {
925         ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, p, NULL,
926                                          "Verify Roots", "Should not be forwarded", __FILE__, __LINE__);
927       }
928     }
929   }
930 
931 public:
932   void do_oop(narrowOop* p) { do_oop_work(p); }
933   void do_oop(oop* p)       { do_oop_work(p); }
934 };
935 
936 class ShenandoahVerifyInToSpaceClosure : public OopClosure {
937 private:
938   template <class T>
939   void do_oop_work(T* p) {
940     T o = RawAccess<>::oop_load(p);
941     if (!CompressedOops::is_null(o)) {
942       oop obj = CompressedOops::decode_not_null(o);
943       ShenandoahHeap* heap = ShenandoahHeap::heap();
944 
945       if (!heap->marking_context()->is_marked(obj)) {
946         ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, p, NULL,
947                 "Verify Roots In To-Space", "Should be marked", __FILE__, __LINE__);
948       }
949 
950       if (heap->in_collection_set(obj)) {
951         ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, p, NULL,
952                 "Verify Roots In To-Space", "Should not be in collection set", __FILE__, __LINE__);
953       }
954 
955       oop fwd = ShenandoahForwarding::get_forwardee_raw_unchecked(obj);
956       if (obj != fwd) {
957         ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, p, NULL,
958                 "Verify Roots In To-Space", "Should not be forwarded", __FILE__, __LINE__);
959       }
960     }
961   }
962 
963 public:
964   void do_oop(narrowOop* p) { do_oop_work(p); }
965   void do_oop(oop* p)       { do_oop_work(p); }
966 };
967 
968 void ShenandoahVerifier::verify_roots_in_to_space() {
969   ShenandoahVerifyInToSpaceClosure cl;
970   ShenandoahRootVerifier::roots_do(&cl);
971 }
972 
973 void ShenandoahVerifier::verify_roots_no_forwarded() {
974   ShenandoahVerifyNoForwared cl;
975   ShenandoahRootVerifier::roots_do(&cl);
976 }