1 /*

     2  * Copyright (c) 2017, 2018, Red Hat, Inc. All rights reserved.

     3  *

     4  * This code is free software; you can redistribute it and/or modify it

     5  * under the terms of the GNU General Public License version 2 only, as

     6  * published by the Free Software Foundation.

     7  *

     8  * This code is distributed in the hope that it will be useful, but WITHOUT

     9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    11  * version 2 for more details (a copy is included in the LICENSE file that

    12  * accompanied this code).

    13  *

    14  * You should have received a copy of the GNU General Public License version

    15  * 2 along with this work; if not, write to the Free Software Foundation,

    16  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    17  *

    18  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    19  * or visit www.oracle.com if you need additional information or have any

    20  * questions.

    21  *

    22  */

    23 

    24 #include "precompiled.hpp"

    25 

    26 #include "gc/shenandoah/shenandoahAsserts.hpp"

    27 #include "gc/shenandoah/shenandoahBrooksPointer.hpp"

    28 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"

    29 #include "gc/shenandoah/shenandoahHeap.hpp"

    30 #include "gc/shenandoah/shenandoahHeap.inline.hpp"

    31 #include "gc/shenandoah/shenandoahRootProcessor.hpp"

    32 #include "gc/shenandoah/shenandoahTaskqueue.hpp"

    33 #include "gc/shenandoah/shenandoahUtils.hpp"

    34 #include "gc/shenandoah/shenandoahVerifier.hpp"

    35 #include "memory/allocation.hpp"

    36 #include "memory/iterator.inline.hpp"

    37 #include "memory/resourceArea.hpp"

    38 

    39 // Avoid name collision on verify_oop (defined in macroAssembler_arm.hpp)

    40 #ifdef verify_oop

    41 #undef verify_oop

    42 #endif

    43 

    44 class ShenandoahVerifyOopClosure : public BasicOopIterateClosure {

    45 private:

    46   const char* _phase;

    47   ShenandoahVerifier::VerifyOptions _options;

    48   ShenandoahVerifierStack* _stack;

    49   ShenandoahHeap* _heap;

    50   MarkBitMap* _map;

    51   ShenandoahLivenessData* _ld;

    52   void* _interior_loc;

    53   oop _loc;

    54 

    55 public:

    56   ShenandoahVerifyOopClosure(ShenandoahVerifierStack* stack, MarkBitMap* map, ShenandoahLivenessData* ld,

    57                              const char* phase, ShenandoahVerifier::VerifyOptions options) :

    58     _phase(phase),

    59     _options(options),

    60     _stack(stack),

    61     _heap(ShenandoahHeap::heap()),

    62     _map(map),

    63     _ld(ld),

    64     _interior_loc(NULL),

    65     _loc(NULL) { }

    66 

    67 private:

    68   void check(ShenandoahAsserts::SafeLevel level, oop obj, bool test, const char* label) {

    69     if (!test) {

    70       ShenandoahAsserts::print_failure(level, obj, _interior_loc, _loc, _phase, label, __FILE__, __LINE__);

    71     }

    72   }

    73 

    74   template <class T>

    75   void do_oop_work(T* p) {

    76     T o = RawAccess<>::oop_load(p);

    77     if (!CompressedOops::is_null(o)) {

    78       oop obj = CompressedOops::decode_not_null(o);

    79 

    80       // Single threaded verification can use faster non-atomic stack and bitmap

    81       // methods.

    82       //

    83       // For performance reasons, only fully verify non-marked field values.

    84       // We are here when the host object for *p is already marked.

    85 

    86       HeapWord* addr = (HeapWord*) obj;

    87       if (_map->par_mark(addr)) {

    88         verify_oop_at(p, obj);

    89         _stack->push(ShenandoahVerifierTask(obj));

    90       }

    91     }

    92   }

    93 

    94   void verify_oop(oop obj) {

    95     // Perform consistency checks with gradually decreasing safety level. This guarantees

    96     // that failure report would not try to touch something that was not yet verified to be

    97     // safe to process.

    98 

    99     check(ShenandoahAsserts::_safe_unknown, obj, _heap->is_in(obj),

   100               "oop must be in heap");

   101     check(ShenandoahAsserts::_safe_unknown, obj, check_obj_alignment(obj),

   102               "oop must be aligned");

   103 

   104     ShenandoahHeapRegion *obj_reg = _heap->heap_region_containing(obj);

   105     Klass* obj_klass = obj->klass_or_null();

   106 

   107     // Verify that obj is not in dead space:

   108     {

   109       // Do this before touching obj->size()

   110       check(ShenandoahAsserts::_safe_unknown, obj, obj_klass != NULL,

   111              "Object klass pointer should not be NULL");

   112       check(ShenandoahAsserts::_safe_unknown, obj, Metaspace::contains(obj_klass),

   113              "Object klass pointer must go to metaspace");

   114 

   115       HeapWord *obj_addr = (HeapWord *) obj;

   116       check(ShenandoahAsserts::_safe_unknown, obj, obj_addr < obj_reg->top(),

   117              "Object start should be within the region");

   118 

   119       if (!obj_reg->is_humongous()) {

   120         check(ShenandoahAsserts::_safe_unknown, obj, (obj_addr + obj->size()) <= obj_reg->top(),

   121                "Object end should be within the region");

   122       } else {

   123         size_t humongous_start = obj_reg->region_number();

   124         size_t humongous_end = humongous_start + (obj->size() >> ShenandoahHeapRegion::region_size_words_shift());

   125         for (size_t idx = humongous_start + 1; idx < humongous_end; idx++) {

   126           check(ShenandoahAsserts::_safe_unknown, obj, _heap->get_region(idx)->is_humongous_continuation(),

   127                  "Humongous object is in continuation that fits it");

   128         }

   129       }

   130 

   131       // ------------ obj is safe at this point --------------

   132 

   133       check(ShenandoahAsserts::_safe_oop, obj, obj_reg->is_active(),

   134             "Object should be in active region");

   135 

   136       switch (_options._verify_liveness) {

   137         case ShenandoahVerifier::_verify_liveness_disable:

   138           // skip

   139           break;

   140         case ShenandoahVerifier::_verify_liveness_complete:

   141           Atomic::add(obj->size() + ShenandoahBrooksPointer::word_size(), &_ld[obj_reg->region_number()]);

   142           // fallthrough for fast failure for un-live regions:

   143         case ShenandoahVerifier::_verify_liveness_conservative:

   144           check(ShenandoahAsserts::_safe_oop, obj, obj_reg->has_live(),

   145                    "Object must belong to region with live data");

   146           break;

   147         default:

   148           assert(false, "Unhandled liveness verification");

   149       }

   150     }

   151 

   152     oop fwd = (oop) ShenandoahBrooksPointer::get_raw_unchecked(obj);

   153 

   154     ShenandoahHeapRegion* fwd_reg = NULL;

   155 

   156     if (!oopDesc::equals_raw(obj, fwd)) {

   157       check(ShenandoahAsserts::_safe_oop, obj, _heap->is_in(fwd),

   158              "Forwardee must be in heap");

   159       check(ShenandoahAsserts::_safe_oop, obj, !CompressedOops::is_null(fwd),

   160              "Forwardee is set");

   161       check(ShenandoahAsserts::_safe_oop, obj, check_obj_alignment(fwd),

   162              "Forwardee must be aligned");

   163 

   164       // Do this before touching fwd->size()

   165       Klass* fwd_klass = fwd->klass_or_null();

   166       check(ShenandoahAsserts::_safe_oop, obj, fwd_klass != NULL,

   167              "Forwardee klass pointer should not be NULL");

   168       check(ShenandoahAsserts::_safe_oop, obj, Metaspace::contains(fwd_klass),

   169              "Forwardee klass pointer must go to metaspace");

   170       check(ShenandoahAsserts::_safe_oop, obj, obj_klass == fwd_klass,

   171              "Forwardee klass pointer must go to metaspace");

   172 

   173       fwd_reg = _heap->heap_region_containing(fwd);

   174 

   175       // Verify that forwardee is not in the dead space:

   176       check(ShenandoahAsserts::_safe_oop, obj, !fwd_reg->is_humongous(),

   177              "Should have no humongous forwardees");

   178 

   179       HeapWord *fwd_addr = (HeapWord *) fwd;

   180       check(ShenandoahAsserts::_safe_oop, obj, fwd_addr < fwd_reg->top(),

   181              "Forwardee start should be within the region");

   182       check(ShenandoahAsserts::_safe_oop, obj, (fwd_addr + fwd->size()) <= fwd_reg->top(),

   183              "Forwardee end should be within the region");

   184 

   185       oop fwd2 = (oop) ShenandoahBrooksPointer::get_raw_unchecked(fwd);

   186       check(ShenandoahAsserts::_safe_oop, obj, oopDesc::equals_raw(fwd, fwd2),

   187              "Double forwarding");

   188     } else {

   189       fwd_reg = obj_reg;

   190     }

   191 

   192     // ------------ obj and fwd are safe at this point --------------

   193 

   194     switch (_options._verify_marked) {

   195       case ShenandoahVerifier::_verify_marked_disable:

   196         // skip

   197         break;

   198       case ShenandoahVerifier::_verify_marked_incomplete:

   199         check(ShenandoahAsserts::_safe_all, obj, _heap->marking_context()->is_marked(obj),

   200                "Must be marked in incomplete bitmap");

   201         break;

   202       case ShenandoahVerifier::_verify_marked_complete:

   203         check(ShenandoahAsserts::_safe_all, obj, _heap->complete_marking_context()->is_marked(obj),

   204                "Must be marked in complete bitmap");

   205         break;

   206       default:

   207         assert(false, "Unhandled mark verification");

   208     }

   209 

   210     switch (_options._verify_forwarded) {

   211       case ShenandoahVerifier::_verify_forwarded_disable:

   212         // skip

   213         break;

   214       case ShenandoahVerifier::_verify_forwarded_none: {

   215         check(ShenandoahAsserts::_safe_all, obj, oopDesc::equals_raw(obj, fwd),

   216                "Should not be forwarded");

   217         break;

   218       }

   219       case ShenandoahVerifier::_verify_forwarded_allow: {

   220         if (!oopDesc::equals_raw(obj, fwd)) {

   221           check(ShenandoahAsserts::_safe_all, obj, obj_reg != fwd_reg,

   222                  "Forwardee should be in another region");

   223         }

   224         break;

   225       }

   226       default:

   227         assert(false, "Unhandled forwarding verification");

   228     }

   229 

   230     switch (_options._verify_cset) {

   231       case ShenandoahVerifier::_verify_cset_disable:

   232         // skip

   233         break;

   234       case ShenandoahVerifier::_verify_cset_none:

   235         check(ShenandoahAsserts::_safe_all, obj, !_heap->in_collection_set(obj),

   236                "Should not have references to collection set");

   237         break;

   238       case ShenandoahVerifier::_verify_cset_forwarded:

   239         if (_heap->in_collection_set(obj)) {

   240           check(ShenandoahAsserts::_safe_all, obj, !oopDesc::equals_raw(obj, fwd),

   241                  "Object in collection set, should have forwardee");

   242         }

   243         break;

   244       default:

   245         assert(false, "Unhandled cset verification");

   246     }

   247 

   248   }

   249 

   250 public:

   251   /**

   252    * Verify object with known interior reference.

   253    * @param p interior reference where the object is referenced from; can be off-heap

   254    * @param obj verified object

   255    */

   256   template <class T>

   257   void verify_oop_at(T* p, oop obj) {

   258     _interior_loc = p;

   259     verify_oop(obj);

   260     _interior_loc = NULL;

   261   }

   262 

   263   /**

   264    * Verify object without known interior reference.

   265    * Useful when picking up the object at known offset in heap,

   266    * but without knowing what objects reference it.

   267    * @param obj verified object

   268    */

   269   void verify_oop_standalone(oop obj) {

   270     _interior_loc = NULL;

   271     verify_oop(obj);

   272     _interior_loc = NULL;

   273   }

   274 

   275   /**

   276    * Verify oop fields from this object.

   277    * @param obj host object for verified fields

   278    */

   279   void verify_oops_from(oop obj) {

   280     _loc = obj;

   281     obj->oop_iterate(this);

   282     _loc = NULL;

   283   }

   284 

   285   virtual void do_oop(oop* p) { do_oop_work(p); }

   286   virtual void do_oop(narrowOop* p) { do_oop_work(p); }

   287 };

   288 

   289 class ShenandoahCalculateRegionStatsClosure : public ShenandoahHeapRegionClosure {

   290 private:

   291   size_t _used, _committed, _garbage;

   292 public:

   293   ShenandoahCalculateRegionStatsClosure() : _used(0), _committed(0), _garbage(0) {};

   294 

   295   void heap_region_do(ShenandoahHeapRegion* r) {

   296     _used += r->used();

   297     _garbage += r->garbage();

   298     _committed += r->is_committed() ? ShenandoahHeapRegion::region_size_bytes() : 0;

   299   }

   300 

   301   size_t used() { return _used; }

   302   size_t committed() { return _committed; }

   303   size_t garbage() { return _garbage; }

   304 };

   305 

   306 class ShenandoahVerifyHeapRegionClosure : public ShenandoahHeapRegionClosure {

   307 private:

   308   ShenandoahHeap* _heap;

   309   const char* _phase;

   310   ShenandoahVerifier::VerifyRegions _regions;

   311 public:

   312   ShenandoahVerifyHeapRegionClosure(const char* phase, ShenandoahVerifier::VerifyRegions regions) :

   313     _heap(ShenandoahHeap::heap()),

   314     _phase(phase),

   315     _regions(regions) {};

   316 

   317   void print_failure(ShenandoahHeapRegion* r, const char* label) {

   318     ResourceMark rm;

   319 

   320     ShenandoahMessageBuffer msg("Shenandoah verification failed; %s: %s\n\n", _phase, label);

   321 

   322     stringStream ss;

   323     r->print_on(&ss);

   324     msg.append("%s", ss.as_string());

   325 

   326     report_vm_error(__FILE__, __LINE__, msg.buffer());

   327   }

   328 

   329   void verify(ShenandoahHeapRegion* r, bool test, const char* msg) {

   330     if (!test) {

   331       print_failure(r, msg);

   332     }

   333   }

   334 

   335   void heap_region_do(ShenandoahHeapRegion* r) {

   336     switch (_regions) {

   337       case ShenandoahVerifier::_verify_regions_disable:

   338         break;

   339       case ShenandoahVerifier::_verify_regions_notrash:

   340         verify(r, !r->is_trash(),

   341                "Should not have trash regions");

   342         break;

   343       case ShenandoahVerifier::_verify_regions_nocset:

   344         verify(r, !r->is_cset(),

   345                "Should not have cset regions");

   346         break;

   347       case ShenandoahVerifier::_verify_regions_notrash_nocset:

   348         verify(r, !r->is_trash(),

   349                "Should not have trash regions");

   350         verify(r, !r->is_cset(),

   351                "Should not have cset regions");

   352         break;

   353       default:

   354         ShouldNotReachHere();

   355     }

   356 

   357     verify(r, r->capacity() == ShenandoahHeapRegion::region_size_bytes(),

   358            "Capacity should match region size");

   359 

   360     verify(r, r->bottom() <= r->top(),

   361            "Region top should not be less than bottom");

   362 

   363     verify(r, r->bottom() <= _heap->marking_context()->top_at_mark_start(r),

   364            "Region TAMS should not be less than bottom");

   365 

   366     verify(r, _heap->marking_context()->top_at_mark_start(r) <= r->top(),

   367            "Complete TAMS should not be larger than top");

   368 

   369     verify(r, r->get_live_data_bytes() <= r->capacity(),

   370            "Live data cannot be larger than capacity");

   371 

   372     verify(r, r->garbage() <= r->capacity(),

   373            "Garbage cannot be larger than capacity");

   374 

   375     verify(r, r->used() <= r->capacity(),

   376            "Used cannot be larger than capacity");

   377 

   378     verify(r, r->get_shared_allocs() <= r->capacity(),

   379            "Shared alloc count should not be larger than capacity");

   380 

   381     verify(r, r->get_tlab_allocs() <= r->capacity(),

   382            "TLAB alloc count should not be larger than capacity");

   383 

   384     verify(r, r->get_gclab_allocs() <= r->capacity(),

   385            "GCLAB alloc count should not be larger than capacity");

   386 

   387     verify(r, r->get_shared_allocs() + r->get_tlab_allocs() + r->get_gclab_allocs() == r->used(),

   388            "Accurate accounting: shared + TLAB + GCLAB = used");

   389 

   390     verify(r, !r->is_empty() || !r->has_live(),

   391            "Empty regions should not have live data");

   392 

   393     verify(r, r->is_cset() == _heap->collection_set()->is_in(r),

   394            "Transitional: region flags and collection set agree");

   395 

   396     verify(r, r->is_empty() || r->seqnum_first_alloc() != 0,

   397            "Non-empty regions should have first seqnum set");

   398 

   399     verify(r, r->is_empty() || (r->seqnum_first_alloc_mutator() != 0 || r->seqnum_first_alloc_gc() != 0),

   400            "Non-empty regions should have first seqnum set to either GC or mutator");

   401 

   402     verify(r, r->is_empty() || r->seqnum_last_alloc() != 0,

   403            "Non-empty regions should have last seqnum set");

   404 

   405     verify(r, r->is_empty() || (r->seqnum_last_alloc_mutator() != 0 || r->seqnum_last_alloc_gc() != 0),

   406            "Non-empty regions should have last seqnum set to either GC or mutator");

   407 

   408     verify(r, r->seqnum_first_alloc() <= r->seqnum_last_alloc(),

   409            "First seqnum should not be greater than last timestamp");

   410 

   411     verify(r, r->seqnum_first_alloc_mutator() <= r->seqnum_last_alloc_mutator(),

   412            "First mutator seqnum should not be greater than last seqnum");

   413 

   414     verify(r, r->seqnum_first_alloc_gc() <= r->seqnum_last_alloc_gc(),

   415            "First GC seqnum should not be greater than last seqnum");

   416   }

   417 };

   418 

   419 class ShenandoahVerifierReachableTask : public AbstractGangTask {

   420 private:

   421   const char* _label;

   422   ShenandoahRootProcessor* _rp;

   423   ShenandoahVerifier::VerifyOptions _options;

   424   ShenandoahHeap* _heap;

   425   ShenandoahLivenessData* _ld;

   426   MarkBitMap* _bitmap;

   427   volatile size_t _processed;

   428 

   429 public:

   430   ShenandoahVerifierReachableTask(MarkBitMap* bitmap,

   431                                   ShenandoahLivenessData* ld,

   432                                   ShenandoahRootProcessor* rp,

   433                                   const char* label,

   434                                   ShenandoahVerifier::VerifyOptions options) :

   435     AbstractGangTask("Shenandoah Parallel Verifier Reachable Task"),

   436     _label(label),

   437     _rp(rp),

   438     _options(options),

   439     _heap(ShenandoahHeap::heap()),

   440     _ld(ld),

   441     _bitmap(bitmap),

   442     _processed(0) {};

   443 

   444   size_t processed() {

   445     return _processed;

   446   }

   447 

   448   virtual void work(uint worker_id) {

   449     ResourceMark rm;

   450     ShenandoahVerifierStack stack;

   451 

   452     // On level 2, we need to only check the roots once.

   453     // On level 3, we want to check the roots, and seed the local stack.

   454     // It is a lesser evil to accept multiple root scans at level 3, because

   455     // extended parallelism would buy us out.

   456     if (((ShenandoahVerifyLevel == 2) && (worker_id == 0))

   457         || (ShenandoahVerifyLevel >= 3)) {

   458         ShenandoahVerifyOopClosure cl(&stack, _bitmap, _ld,

   459                                       ShenandoahMessageBuffer("%s, Roots", _label),

   460                                       _options);

   461         _rp->process_all_roots_slow(&cl);

   462     }

   463 

   464     size_t processed = 0;

   465 

   466     if (ShenandoahVerifyLevel >= 3) {

   467       ShenandoahVerifyOopClosure cl(&stack, _bitmap, _ld,

   468                                     ShenandoahMessageBuffer("%s, Reachable", _label),

   469                                     _options);

   470       while (!stack.is_empty()) {

   471         processed++;

   472         ShenandoahVerifierTask task = stack.pop();

   473         cl.verify_oops_from(task.obj());

   474       }

   475     }

   476 

   477     Atomic::add(processed, &_processed);

   478   }

   479 };

   480 

   481 class ShenandoahVerifierMarkedRegionTask : public AbstractGangTask {

   482 private:

   483   const char* _label;

   484   ShenandoahVerifier::VerifyOptions _options;

   485   ShenandoahHeap *_heap;

   486   MarkBitMap* _bitmap;

   487   ShenandoahLivenessData* _ld;

   488   volatile size_t _claimed;

   489   volatile size_t _processed;

   490 

   491 public:

   492   ShenandoahVerifierMarkedRegionTask(MarkBitMap* bitmap,

   493                                      ShenandoahLivenessData* ld,

   494                                      const char* label,

   495                                      ShenandoahVerifier::VerifyOptions options) :

   496           AbstractGangTask("Shenandoah Parallel Verifier Marked Region"),

   497           _label(label),

   498           _options(options),

   499           _heap(ShenandoahHeap::heap()),

   500           _bitmap(bitmap),

   501           _ld(ld),

   502           _claimed(0),

   503           _processed(0) {};

   504 

   505   size_t processed() {

   506     return _processed;

   507   }

   508 

   509   virtual void work(uint worker_id) {

   510     ShenandoahVerifierStack stack;

   511     ShenandoahVerifyOopClosure cl(&stack, _bitmap, _ld,

   512                                   ShenandoahMessageBuffer("%s, Marked", _label),

   513                                   _options);

   514 

   515     while (true) {

   516       size_t v = Atomic::add(1u, &_claimed) - 1;

   517       if (v < _heap->num_regions()) {

   518         ShenandoahHeapRegion* r = _heap->get_region(v);

   519         if (!r->is_humongous() && !r->is_trash()) {

   520           work_regular(r, stack, cl);

   521         } else if (r->is_humongous_start()) {

   522           work_humongous(r, stack, cl);

   523         }

   524       } else {

   525         break;

   526       }

   527     }

   528   }

   529 

   530   virtual void work_humongous(ShenandoahHeapRegion *r, ShenandoahVerifierStack& stack, ShenandoahVerifyOopClosure& cl) {

   531     size_t processed = 0;

   532     HeapWord* obj = r->bottom() + ShenandoahBrooksPointer::word_size();

   533     if (_heap->complete_marking_context()->is_marked((oop)obj)) {

   534       verify_and_follow(obj, stack, cl, &processed);

   535     }

   536     Atomic::add(processed, &_processed);

   537   }

   538 

   539   virtual void work_regular(ShenandoahHeapRegion *r, ShenandoahVerifierStack &stack, ShenandoahVerifyOopClosure &cl) {

   540     size_t processed = 0;

   541     MarkBitMap* mark_bit_map = _heap->complete_marking_context()->mark_bit_map();

   542     HeapWord* tams = _heap->complete_marking_context()->top_at_mark_start(r);

   543 

   544     // Bitmaps, before TAMS

   545     if (tams > r->bottom()) {

   546       HeapWord* start = r->bottom() + ShenandoahBrooksPointer::word_size();

   547       HeapWord* addr = mark_bit_map->get_next_marked_addr(start, tams);

   548 

   549       while (addr < tams) {

   550         verify_and_follow(addr, stack, cl, &processed);

   551         addr += ShenandoahBrooksPointer::word_size();

   552         if (addr < tams) {

   553           addr = mark_bit_map->get_next_marked_addr(addr, tams);

   554         }

   555       }

   556     }

   557 

   558     // Size-based, after TAMS

   559     {

   560       HeapWord* limit = r->top();

   561       HeapWord* addr = tams + ShenandoahBrooksPointer::word_size();

   562 

   563       while (addr < limit) {

   564         verify_and_follow(addr, stack, cl, &processed);

   565         addr += oop(addr)->size() + ShenandoahBrooksPointer::word_size();

   566       }

   567     }

   568 

   569     Atomic::add(processed, &_processed);

   570   }

   571 

   572   void verify_and_follow(HeapWord *addr, ShenandoahVerifierStack &stack, ShenandoahVerifyOopClosure &cl, size_t *processed) {

   573     if (!_bitmap->par_mark(addr)) return;

   574 

   575     // Verify the object itself:

   576     oop obj = oop(addr);

   577     cl.verify_oop_standalone(obj);

   578 

   579     // Verify everything reachable from that object too, hopefully realizing

   580     // everything was already marked, and never touching further:

   581     cl.verify_oops_from(obj);

   582     (*processed)++;

   583 

   584     while (!stack.is_empty()) {

   585       ShenandoahVerifierTask task = stack.pop();

   586       cl.verify_oops_from(task.obj());

   587       (*processed)++;

   588     }

   589   }

   590 };

   591 

   592 class VerifyThreadGCState : public ThreadClosure {

   593 private:

   594   const char* _label;

   595   char _expected;

   596 

   597 public:

   598   VerifyThreadGCState(const char* label, char expected) : _expected(expected) {}

   599   void do_thread(Thread* t) {

   600     char actual = ShenandoahThreadLocalData::gc_state(t);

   601     if (actual != _expected) {

   602       fatal("%s: Thread %s: expected gc-state %d, actual %d", _label, t->name(), _expected, actual);

   603     }

   604   }

   605 };

   606 

   607 void ShenandoahVerifier::verify_at_safepoint(const char *label,

   608                                              VerifyForwarded forwarded, VerifyMarked marked,

   609                                              VerifyCollectionSet cset,

   610                                              VerifyLiveness liveness, VerifyRegions regions,

   611                                              VerifyGCState gcstate) {

   612   guarantee(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "only when nothing else happens");

   613   guarantee(ShenandoahVerify, "only when enabled, and bitmap is initialized in ShenandoahHeap::initialize");

   614 

   615   // Avoid side-effect of changing workers' active thread count, but bypass concurrent/parallel protocol check

   616   ShenandoahPushWorkerScope verify_worker_scope(_heap->workers(), _heap->max_workers(), false /*bypass check*/);

   617 

   618   log_info(gc,start)("Verify %s, Level " INTX_FORMAT, label, ShenandoahVerifyLevel);

   619 

   620   // GC state checks

   621   {

   622     char expected = -1;

   623     bool enabled;

   624     switch (gcstate) {

   625       case _verify_gcstate_disable:

   626         enabled = false;

   627         break;

   628       case _verify_gcstate_forwarded:

   629         enabled = true;

   630         expected = ShenandoahHeap::HAS_FORWARDED;

   631         break;

   632       case _verify_gcstate_stable:

   633         enabled = true;

   634         expected = ShenandoahHeap::STABLE;

   635         break;

   636       default:

   637         enabled = false;

   638         assert(false, "Unhandled gc-state verification");

   639     }

   640 

   641     if (enabled) {

   642       char actual = _heap->gc_state();

   643       if (actual != expected) {

   644         fatal("%s: Global gc-state: expected %d, actual %d", label, expected, actual);

   645       }

   646 

   647       VerifyThreadGCState vtgcs(label, expected);

   648       Threads::java_threads_do(&vtgcs);

   649     }

   650   }

   651 

   652   // Heap size checks

   653   {

   654     ShenandoahHeapLocker lock(_heap->lock());

   655 

   656     ShenandoahCalculateRegionStatsClosure cl;

   657     _heap->heap_region_iterate(&cl);

   658     size_t heap_used = _heap->used();

   659     guarantee(cl.used() == heap_used,

   660               "%s: heap used size must be consistent: heap-used = " SIZE_FORMAT "K, regions-used = " SIZE_FORMAT "K",

   661               label, heap_used/K, cl.used()/K);

   662 

   663     size_t heap_committed = _heap->committed();

   664     guarantee(cl.committed() == heap_committed,

   665               "%s: heap committed size must be consistent: heap-committed = " SIZE_FORMAT "K, regions-committed = " SIZE_FORMAT "K",

   666               label, heap_committed/K, cl.committed()/K);

   667   }

   668 

   669   // Internal heap region checks

   670   if (ShenandoahVerifyLevel >= 1) {

   671     ShenandoahVerifyHeapRegionClosure cl(label, regions);

   672     _heap->heap_region_iterate(&cl);

   673   }

   674 

   675   OrderAccess::fence();

   676   _heap->make_parsable(false);

   677 

   678   // Allocate temporary bitmap for storing marking wavefront:

   679   _verification_bit_map->clear();

   680 

   681   // Allocate temporary array for storing liveness data

   682   ShenandoahLivenessData* ld = NEW_C_HEAP_ARRAY(ShenandoahLivenessData, _heap->num_regions(), mtGC);

   683   Copy::fill_to_bytes((void*)ld, _heap->num_regions()*sizeof(ShenandoahLivenessData), 0);

   684 

   685   const VerifyOptions& options = ShenandoahVerifier::VerifyOptions(forwarded, marked, cset, liveness, regions, gcstate);

   686 

   687   // Steps 1-2. Scan root set to get initial reachable set. Finish walking the reachable heap.

   688   // This verifies what application can see, since it only cares about reachable objects.

   689   size_t count_reachable = 0;

   690   if (ShenandoahVerifyLevel >= 2) {

   691     ShenandoahRootProcessor rp(_heap, _heap->workers()->active_workers(),

   692                                ShenandoahPhaseTimings::_num_phases); // no need for stats

   693 

   694     ShenandoahVerifierReachableTask task(_verification_bit_map, ld, &rp, label, options);

   695     _heap->workers()->run_task(&task);

   696     count_reachable = task.processed();

   697   }

   698 

   699   // Step 3. Walk marked objects. Marked objects might be unreachable. This verifies what collector,

   700   // not the application, can see during the region scans. There is no reason to process the objects

   701   // that were already verified, e.g. those marked in verification bitmap. There is interaction with TAMS:

   702   // before TAMS, we verify the bitmaps, if available; after TAMS, we walk until the top(). It mimics

   703   // what marked_object_iterate is doing, without calling into that optimized (and possibly incorrect)

   704   // version

   705 

   706   size_t count_marked = 0;

   707   if (ShenandoahVerifyLevel >= 4 && marked == _verify_marked_complete) {

   708     guarantee(_heap->marking_context()->is_complete(), "Marking context should be complete");

   709     ShenandoahVerifierMarkedRegionTask task(_verification_bit_map, ld, label, options);

   710     _heap->workers()->run_task(&task);

   711     count_marked = task.processed();

   712   } else {

   713     guarantee(ShenandoahVerifyLevel < 4 || marked == _verify_marked_incomplete || marked == _verify_marked_disable, "Should be");

   714   }

   715 

   716   // Step 4. Verify accumulated liveness data, if needed. Only reliable if verification level includes

   717   // marked objects.

   718 

   719   if (ShenandoahVerifyLevel >= 4 && marked == _verify_marked_complete && liveness == _verify_liveness_complete) {

   720     for (size_t i = 0; i < _heap->num_regions(); i++) {

   721       ShenandoahHeapRegion* r = _heap->get_region(i);

   722 

   723       juint verf_live = 0;

   724       if (r->is_humongous()) {

   725         // For humongous objects, test if start region is marked live, and if so,

   726         // all humongous regions in that chain have live data equal to their "used".

   727         juint start_live = OrderAccess::load_acquire(&ld[r->humongous_start_region()->region_number()]);

   728         if (start_live > 0) {

   729           verf_live = (juint)(r->used() / HeapWordSize);

   730         }

   731       } else {

   732         verf_live = OrderAccess::load_acquire(&ld[r->region_number()]);

   733       }

   734 

   735       size_t reg_live = r->get_live_data_words();

   736       if (reg_live != verf_live) {

   737         ResourceMark rm;

   738         stringStream ss;

   739         r->print_on(&ss);

   740         fatal("%s: Live data should match: region-live = " SIZE_FORMAT ", verifier-live = " UINT32_FORMAT "\n%s",

   741               label, reg_live, verf_live, ss.as_string());

   742       }

   743     }

   744   }

   745 

   746   log_info(gc)("Verify %s, Level " INTX_FORMAT " (" SIZE_FORMAT " reachable, " SIZE_FORMAT " marked)",

   747                label, ShenandoahVerifyLevel, count_reachable, count_marked);

   748 

   749   FREE_C_HEAP_ARRAY(ShenandoahLivenessData, ld);

   750 }

   751 

   752 void ShenandoahVerifier::verify_generic(VerifyOption vo) {

   753   verify_at_safepoint(

   754           "Generic Verification",

   755           _verify_forwarded_allow,     // conservatively allow forwarded

   756           _verify_marked_disable,      // do not verify marked: lots ot time wasted checking dead allocations

   757           _verify_cset_disable,        // cset may be inconsistent

   758           _verify_liveness_disable,    // no reliable liveness data

   759           _verify_regions_disable,     // no reliable region data

   760           _verify_gcstate_disable      // no data about gcstate

   761   );

   762 }

   763 

   764 void ShenandoahVerifier::verify_before_concmark() {

   765   if (_heap->has_forwarded_objects()) {

   766     verify_at_safepoint(

   767             "Before Mark",

   768             _verify_forwarded_allow,     // may have forwarded references

   769             _verify_marked_disable,      // do not verify marked: lots ot time wasted checking dead allocations

   770             _verify_cset_forwarded,      // allow forwarded references to cset

   771             _verify_liveness_disable,    // no reliable liveness data

   772             _verify_regions_notrash,     // no trash regions

   773             _verify_gcstate_forwarded    // there are forwarded objects

   774     );

   775   } else {

   776     verify_at_safepoint(

   777             "Before Mark",

   778             _verify_forwarded_none,      // UR should have fixed up

   779             _verify_marked_disable,      // do not verify marked: lots ot time wasted checking dead allocations

   780             _verify_cset_none,           // UR should have fixed this

   781             _verify_liveness_disable,    // no reliable liveness data

   782             _verify_regions_notrash,     // no trash regions

   783             _verify_gcstate_stable       // there are no forwarded objects

   784     );

   785   }

   786 }

   787 

   788 void ShenandoahVerifier::verify_after_concmark() {

   789   verify_at_safepoint(

   790           "After Mark",

   791           _verify_forwarded_none,      // no forwarded references

   792           _verify_marked_complete,     // bitmaps as precise as we can get

   793           _verify_cset_none,           // no references to cset anymore

   794           _verify_liveness_complete,   // liveness data must be complete here

   795           _verify_regions_disable,     // trash regions not yet recycled

   796           _verify_gcstate_stable       // mark should have stabilized the heap

   797   );

   798 }

   799 

   800 void ShenandoahVerifier::verify_before_evacuation() {

   801   verify_at_safepoint(

   802           "Before Evacuation",

   803           _verify_forwarded_none,    // no forwarded references

   804           _verify_marked_complete,   // walk over marked objects too

   805           _verify_cset_disable,      // non-forwarded references to cset expected

   806           _verify_liveness_complete, // liveness data must be complete here

   807           _verify_regions_disable,   // trash regions not yet recycled

   808           _verify_gcstate_stable     // mark should have stabilized the heap

   809   );

   810 }

   811 

   812 void ShenandoahVerifier::verify_after_evacuation() {

   813   verify_at_safepoint(

   814           "After Evacuation",

   815           _verify_forwarded_allow,     // objects are still forwarded

   816           _verify_marked_complete,     // bitmaps might be stale, but alloc-after-mark should be well

   817           _verify_cset_forwarded,      // all cset refs are fully forwarded

   818           _verify_liveness_disable,    // no reliable liveness data anymore

   819           _verify_regions_notrash,     // trash regions have been recycled already

   820           _verify_gcstate_forwarded    // evacuation produced some forwarded objects

   821   );

   822 }

   823 

   824 void ShenandoahVerifier::verify_before_updaterefs() {

   825   verify_at_safepoint(

   826           "Before Updating References",

   827           _verify_forwarded_allow,     // forwarded references allowed

   828           _verify_marked_complete,     // bitmaps might be stale, but alloc-after-mark should be well

   829           _verify_cset_forwarded,      // all cset refs are fully forwarded

   830           _verify_liveness_disable,    // no reliable liveness data anymore

   831           _verify_regions_notrash,     // trash regions have been recycled already

   832           _verify_gcstate_forwarded    // evacuation should have produced some forwarded objects

   833   );

   834 }

   835 

   836 void ShenandoahVerifier::verify_after_updaterefs() {

   837   verify_at_safepoint(

   838           "After Updating References",

   839           _verify_forwarded_none,      // no forwarded references

   840           _verify_marked_complete,     // bitmaps might be stale, but alloc-after-mark should be well

   841           _verify_cset_none,           // no cset references, all updated

   842           _verify_liveness_disable,    // no reliable liveness data anymore

   843           _verify_regions_nocset,      // no cset regions, trash regions have appeared

   844           _verify_gcstate_stable       // update refs had cleaned up forwarded objects

   845   );

   846 }

   847 

   848 void ShenandoahVerifier::verify_after_degenerated() {

   849   verify_at_safepoint(

   850           "After Degenerated GC",

   851           _verify_forwarded_none,      // all objects are non-forwarded

   852           _verify_marked_complete,     // all objects are marked in complete bitmap

   853           _verify_cset_none,           // no cset references

   854           _verify_liveness_disable,    // no reliable liveness data anymore

   855           _verify_regions_notrash_nocset, // no trash, no cset

   856           _verify_gcstate_stable       // degenerated refs had cleaned up forwarded objects

   857   );

   858 }

   859 

   860 void ShenandoahVerifier::verify_before_traversal() {

   861   verify_at_safepoint(

   862           "Before Traversal",

   863           _verify_forwarded_none,      // cannot have forwarded objects

   864           _verify_marked_disable,      // bitmaps are not relevant before traversal

   865           _verify_cset_none,           // no cset references before traversal

   866           _verify_liveness_disable,    // no reliable liveness data anymore

   867           _verify_regions_notrash_nocset, // no trash and no cset regions

   868           _verify_gcstate_stable       // nothing forwarded before traversal

   869   );

   870 }

   871 

   872 void ShenandoahVerifier::verify_after_traversal() {

   873   verify_at_safepoint(

   874           "After Traversal",

   875           _verify_forwarded_none,      // cannot have forwarded objects

   876           _verify_marked_complete,     // should have complete marking after traversal

   877           _verify_cset_none,           // no cset references left after traversal

   878           _verify_liveness_disable,    // liveness data is not collected for new allocations

   879           _verify_regions_nocset,      // no cset regions, trash regions allowed

   880           _verify_gcstate_stable       // nothing forwarded after traversal

   881   );

   882 }

   883 

   884 void ShenandoahVerifier::verify_before_fullgc() {

   885   verify_at_safepoint(

   886           "Before Full GC",

   887           _verify_forwarded_allow,     // can have forwarded objects

   888           _verify_marked_disable,      // do not verify marked: lots ot time wasted checking dead allocations

   889           _verify_cset_disable,        // cset might be foobared

   890           _verify_liveness_disable,    // no reliable liveness data anymore

   891           _verify_regions_disable,     // no reliable region data here

   892           _verify_gcstate_disable      // no reliable gcstate data

   893   );

   894 }

   895 

   896 void ShenandoahVerifier::verify_after_fullgc() {

   897   verify_at_safepoint(

   898           "After Full GC",

   899           _verify_forwarded_none,      // all objects are non-forwarded

   900           _verify_marked_complete,     // all objects are marked in complete bitmap

   901           _verify_cset_none,           // no cset references

   902           _verify_liveness_disable,    // no reliable liveness data anymore

   903           _verify_regions_notrash_nocset, // no trash, no cset

   904           _verify_gcstate_stable       // full gc cleaned up everything

   905   );

   906 }