1 /*

     2  * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

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

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

     7  * published by the Free Software Foundation.

     8  *

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

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

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

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

    13  * accompanied this code).

    14  *

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

    16  * 2 along with this work; if not, write to the Free Software Foundation,

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

    18  *

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

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

    21  * questions.

    22  *

    23  */

    24 

    25 #include "precompiled.hpp"

    26 #include "code/nmethod.hpp"

    27 #include "gc/g1/g1BlockOffsetTable.inline.hpp"

    28 #include "gc/g1/g1CollectedHeap.inline.hpp"

    29 #include "gc/g1/g1OopClosures.inline.hpp"

    30 #include "gc/g1/heapRegion.inline.hpp"

    31 #include "gc/g1/heapRegionBounds.inline.hpp"

    32 #include "gc/g1/heapRegionManager.inline.hpp"

    33 #include "gc/g1/heapRegionRemSet.hpp"

    34 #include "gc/shared/genOopClosures.inline.hpp"

    35 #include "gc/shared/liveRange.hpp"

    36 #include "gc/shared/space.inline.hpp"

    37 #include "memory/iterator.hpp"

    38 #include "oops/oop.inline.hpp"

    39 #include "runtime/atomic.inline.hpp"

    40 #include "runtime/orderAccess.inline.hpp"

    41 

    42 int    HeapRegion::LogOfHRGrainBytes = 0;

    43 int    HeapRegion::LogOfHRGrainWords = 0;

    44 size_t HeapRegion::GrainBytes        = 0;

    45 size_t HeapRegion::GrainWords        = 0;

    46 size_t HeapRegion::CardsPerRegion    = 0;

    47 

    48 HeapRegionDCTOC::HeapRegionDCTOC(G1CollectedHeap* g1,

    49                                  HeapRegion* hr,

    50                                  G1ParPushHeapRSClosure* cl,

    51                                  CardTableModRefBS::PrecisionStyle precision) :

    52   DirtyCardToOopClosure(hr, cl, precision, NULL),

    53   _hr(hr), _rs_scan(cl), _g1(g1) { }

    54 

    55 FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r,

    56                                                    OopClosure* oc) :

    57   _r_bottom(r->bottom()), _r_end(r->end()), _oc(oc) { }

    58 

    59 void HeapRegionDCTOC::walk_mem_region(MemRegion mr,

    60                                       HeapWord* bottom,

    61                                       HeapWord* top) {

    62   G1CollectedHeap* g1h = _g1;

    63   size_t oop_size;

    64   HeapWord* cur = bottom;

    65 

    66   // Start filtering what we add to the remembered set. If the object is

    67   // not considered dead, either because it is marked (in the mark bitmap)

    68   // or it was allocated after marking finished, then we add it. Otherwise

    69   // we can safely ignore the object.

    70   if (!g1h->is_obj_dead(oop(cur), _hr)) {

    71     oop_size = oop(cur)->oop_iterate(_rs_scan, mr);

    72   } else {

    73     oop_size = _hr->block_size(cur);

    74   }

    75 

    76   cur += oop_size;

    77 

    78   if (cur < top) {

    79     oop cur_oop = oop(cur);

    80     oop_size = _hr->block_size(cur);

    81     HeapWord* next_obj = cur + oop_size;

    82     while (next_obj < top) {

    83       // Keep filtering the remembered set.

    84       if (!g1h->is_obj_dead(cur_oop, _hr)) {

    85         // Bottom lies entirely below top, so we can call the

    86         // non-memRegion version of oop_iterate below.

    87         cur_oop->oop_iterate(_rs_scan);

    88       }

    89       cur = next_obj;

    90       cur_oop = oop(cur);

    91       oop_size = _hr->block_size(cur);

    92       next_obj = cur + oop_size;

    93     }

    94 

    95     // Last object. Need to do dead-obj filtering here too.

    96     if (!g1h->is_obj_dead(oop(cur), _hr)) {

    97       oop(cur)->oop_iterate(_rs_scan, mr);

    98     }

    99   }

   100 }

   101 

   102 size_t HeapRegion::max_region_size() {

   103   return HeapRegionBounds::max_size();

   104 }

   105 

   106 void HeapRegion::setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size) {

   107   size_t region_size = G1HeapRegionSize;

   108   if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {

   109     size_t average_heap_size = (initial_heap_size + max_heap_size) / 2;

   110     region_size = MAX2(average_heap_size / HeapRegionBounds::target_number(),

   111                        HeapRegionBounds::min_size());

   112   }

   113 

   114   int region_size_log = log2_long((jlong) region_size);

   115   // Recalculate the region size to make sure it's a power of

   116   // 2. This means that region_size is the largest power of 2 that's

   117   // <= what we've calculated so far.

   118   region_size = ((size_t)1 << region_size_log);

   119 

   120   // Now make sure that we don't go over or under our limits.

   121   if (region_size < HeapRegionBounds::min_size()) {

   122     region_size = HeapRegionBounds::min_size();

   123   } else if (region_size > HeapRegionBounds::max_size()) {

   124     region_size = HeapRegionBounds::max_size();

   125   }

   126 

   127   // And recalculate the log.

   128   region_size_log = log2_long((jlong) region_size);

   129 

   130   // Now, set up the globals.

   131   guarantee(LogOfHRGrainBytes == 0, "we should only set it once");

   132   LogOfHRGrainBytes = region_size_log;

   133 

   134   guarantee(LogOfHRGrainWords == 0, "we should only set it once");

   135   LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize;

   136 

   137   guarantee(GrainBytes == 0, "we should only set it once");

   138   // The cast to int is safe, given that we've bounded region_size by

   139   // MIN_REGION_SIZE and MAX_REGION_SIZE.

   140   GrainBytes = region_size;

   141 

   142   guarantee(GrainWords == 0, "we should only set it once");

   143   GrainWords = GrainBytes >> LogHeapWordSize;

   144   guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity");

   145 

   146   guarantee(CardsPerRegion == 0, "we should only set it once");

   147   CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift;

   148 }

   149 

   150 void HeapRegion::reset_after_compaction() {

   151   G1OffsetTableContigSpace::reset_after_compaction();

   152   // After a compaction the mark bitmap is invalid, so we must

   153   // treat all objects as being inside the unmarked area.

   154   zero_marked_bytes();

   155   init_top_at_mark_start();

   156 }

   157 

   158 void HeapRegion::hr_clear(bool par, bool clear_space, bool locked) {

   159   assert(_humongous_start_region == NULL,

   160          "we should have already filtered out humongous regions");

   161   assert(_end == orig_end(),

   162          "we should have already filtered out humongous regions");

   163   assert(!in_collection_set(),

   164          err_msg("Should not clear heap region %u in the collection set", hrm_index()));

   165 

   166   set_allocation_context(AllocationContext::system());

   167   set_young_index_in_cset(-1);

   168   uninstall_surv_rate_group();

   169   set_free();

   170   reset_pre_dummy_top();

   171 

   172   if (!par) {

   173     // If this is parallel, this will be done later.

   174     HeapRegionRemSet* hrrs = rem_set();

   175     if (locked) {

   176       hrrs->clear_locked();

   177     } else {

   178       hrrs->clear();

   179     }

   180   }

   181   zero_marked_bytes();

   182 

   183   _offsets.resize(HeapRegion::GrainWords);

   184   init_top_at_mark_start();

   185   if (clear_space) clear(SpaceDecorator::Mangle);

   186 }

   187 

   188 void HeapRegion::par_clear() {

   189   assert(used() == 0, "the region should have been already cleared");

   190   assert(capacity() == HeapRegion::GrainBytes, "should be back to normal");

   191   HeapRegionRemSet* hrrs = rem_set();

   192   hrrs->clear();

   193   CardTableModRefBS* ct_bs =

   194     barrier_set_cast<CardTableModRefBS>(G1CollectedHeap::heap()->barrier_set());

   195   ct_bs->clear(MemRegion(bottom(), end()));

   196 }

   197 

   198 void HeapRegion::calc_gc_efficiency() {

   199   // GC efficiency is the ratio of how much space would be

   200   // reclaimed over how long we predict it would take to reclaim it.

   201   G1CollectedHeap* g1h = G1CollectedHeap::heap();

   202   G1CollectorPolicy* g1p = g1h->g1_policy();

   203 

   204   // Retrieve a prediction of the elapsed time for this region for

   205   // a mixed gc because the region will only be evacuated during a

   206   // mixed gc.

   207   double region_elapsed_time_ms =

   208     g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */);

   209   _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms;

   210 }

   211 

   212 void HeapRegion::set_starts_humongous(HeapWord* new_top, HeapWord* new_end) {

   213   assert(!is_humongous(), "sanity / pre-condition");

   214   assert(end() == orig_end(),

   215          "Should be normal before the humongous object allocation");

   216   assert(top() == bottom(), "should be empty");

   217   assert(bottom() <= new_top && new_top <= new_end, "pre-condition");

   218 

   219   _type.set_starts_humongous();

   220   _humongous_start_region = this;

   221 

   222   set_end(new_end);

   223   _offsets.set_for_starts_humongous(new_top);

   224 }

   225 

   226 void HeapRegion::set_continues_humongous(HeapRegion* first_hr) {

   227   assert(!is_humongous(), "sanity / pre-condition");

   228   assert(end() == orig_end(),

   229          "Should be normal before the humongous object allocation");

   230   assert(top() == bottom(), "should be empty");

   231   assert(first_hr->is_starts_humongous(), "pre-condition");

   232 

   233   _type.set_continues_humongous();

   234   _humongous_start_region = first_hr;

   235 }

   236 

   237 void HeapRegion::clear_humongous() {

   238   assert(is_humongous(), "pre-condition");

   239 

   240   if (is_starts_humongous()) {

   241     assert(top() <= end(), "pre-condition");

   242     set_end(orig_end());

   243     if (top() > end()) {

   244       // at least one "continues humongous" region after it

   245       set_top(end());

   246     }

   247   } else {

   248     // continues humongous

   249     assert(end() == orig_end(), "sanity");

   250   }

   251 

   252   assert(capacity() == HeapRegion::GrainBytes, "pre-condition");

   253   _humongous_start_region = NULL;

   254 }

   255 

   256 HeapRegion::HeapRegion(uint hrm_index,

   257                        G1BlockOffsetSharedArray* sharedOffsetArray,

   258                        MemRegion mr) :

   259     G1OffsetTableContigSpace(sharedOffsetArray, mr),

   260     _hrm_index(hrm_index),

   261     _allocation_context(AllocationContext::system()),

   262     _humongous_start_region(NULL),

   263     _next_in_special_set(NULL),

   264     _evacuation_failed(false),

   265     _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0),

   266     _next_young_region(NULL),

   267     _next_dirty_cards_region(NULL), _next(NULL), _prev(NULL),

   268 #ifdef ASSERT

   269     _containing_set(NULL),

   270 #endif // ASSERT

   271      _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),

   272     _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),

   273     _predicted_bytes_to_copy(0)

   274 {

   275   _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);

   276   assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");

   277 

   278   initialize(mr);

   279 }

   280 

   281 void HeapRegion::initialize(MemRegion mr, bool clear_space, bool mangle_space) {

   282   assert(_rem_set->is_empty(), "Remembered set must be empty");

   283 

   284   G1OffsetTableContigSpace::initialize(mr, clear_space, mangle_space);

   285 

   286   hr_clear(false /*par*/, false /*clear_space*/);

   287   set_top(bottom());

   288   record_timestamp();

   289 

   290   assert(mr.end() == orig_end(),

   291          err_msg("Given region end address " PTR_FORMAT " should match exactly "

   292                  "bottom plus one region size, i.e. " PTR_FORMAT,

   293                  p2i(mr.end()), p2i(orig_end())));

   294 }

   295 

   296 CompactibleSpace* HeapRegion::next_compaction_space() const {

   297   return G1CollectedHeap::heap()->next_compaction_region(this);

   298 }

   299 

   300 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,

   301                                                     bool during_conc_mark) {

   302   // We always recreate the prev marking info and we'll explicitly

   303   // mark all objects we find to be self-forwarded on the prev

   304   // bitmap. So all objects need to be below PTAMS.

   305   _prev_marked_bytes = 0;

   306 

   307   if (during_initial_mark) {

   308     // During initial-mark, we'll also explicitly mark all objects

   309     // we find to be self-forwarded on the next bitmap. So all

   310     // objects need to be below NTAMS.

   311     _next_top_at_mark_start = top();

   312     _next_marked_bytes = 0;

   313   } else if (during_conc_mark) {

   314     // During concurrent mark, all objects in the CSet (including

   315     // the ones we find to be self-forwarded) are implicitly live.

   316     // So all objects need to be above NTAMS.

   317     _next_top_at_mark_start = bottom();

   318     _next_marked_bytes = 0;

   319   }

   320 }

   321 

   322 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark,

   323                                                   bool during_conc_mark,

   324                                                   size_t marked_bytes) {

   325   assert(marked_bytes <= used(),

   326          err_msg("marked: "SIZE_FORMAT" used: "SIZE_FORMAT, marked_bytes, used()));

   327   _prev_top_at_mark_start = top();

   328   _prev_marked_bytes = marked_bytes;

   329 }

   330 

   331 HeapWord*

   332 HeapRegion::object_iterate_mem_careful(MemRegion mr,

   333                                                  ObjectClosure* cl) {

   334   G1CollectedHeap* g1h = G1CollectedHeap::heap();

   335   // We used to use "block_start_careful" here.  But we're actually happy

   336   // to update the BOT while we do this...

   337   HeapWord* cur = block_start(mr.start());

   338   mr = mr.intersection(used_region());

   339   if (mr.is_empty()) return NULL;

   340   // Otherwise, find the obj that extends onto mr.start().

   341 

   342   assert(cur <= mr.start()

   343          && (oop(cur)->klass_or_null() == NULL ||

   344              cur + oop(cur)->size() > mr.start()),

   345          "postcondition of block_start");

   346   oop obj;

   347   while (cur < mr.end()) {

   348     obj = oop(cur);

   349     if (obj->klass_or_null() == NULL) {

   350       // Ran into an unparseable point.

   351       return cur;

   352     } else if (!g1h->is_obj_dead(obj)) {

   353       cl->do_object(obj);

   354     }

   355     cur += block_size(cur);

   356   }

   357   return NULL;

   358 }

   359 

   360 HeapWord*

   361 HeapRegion::

   362 oops_on_card_seq_iterate_careful(MemRegion mr,

   363                                  FilterOutOfRegionClosure* cl,

   364                                  bool filter_young,

   365                                  jbyte* card_ptr) {

   366   // Currently, we should only have to clean the card if filter_young

   367   // is true and vice versa.

   368   if (filter_young) {

   369     assert(card_ptr != NULL, "pre-condition");

   370   } else {

   371     assert(card_ptr == NULL, "pre-condition");

   372   }

   373   G1CollectedHeap* g1h = G1CollectedHeap::heap();

   374 

   375   // If we're within a stop-world GC, then we might look at a card in a

   376   // GC alloc region that extends onto a GC LAB, which may not be

   377   // parseable.  Stop such at the "scan_top" of the region.

   378   if (g1h->is_gc_active()) {

   379     mr = mr.intersection(MemRegion(bottom(), scan_top()));

   380   } else {

   381     mr = mr.intersection(used_region());

   382   }

   383   if (mr.is_empty()) return NULL;

   384   // Otherwise, find the obj that extends onto mr.start().

   385 

   386   // The intersection of the incoming mr (for the card) and the

   387   // allocated part of the region is non-empty. This implies that

   388   // we have actually allocated into this region. The code in

   389   // G1CollectedHeap.cpp that allocates a new region sets the

   390   // is_young tag on the region before allocating. Thus we

   391   // safely know if this region is young.

   392   if (is_young() && filter_young) {

   393     return NULL;

   394   }

   395 

   396   assert(!is_young(), "check value of filter_young");

   397 

   398   // We can only clean the card here, after we make the decision that

   399   // the card is not young. And we only clean the card if we have been

   400   // asked to (i.e., card_ptr != NULL).

   401   if (card_ptr != NULL) {

   402     *card_ptr = CardTableModRefBS::clean_card_val();

   403     // We must complete this write before we do any of the reads below.

   404     OrderAccess::storeload();

   405   }

   406 

   407   // Cache the boundaries of the memory region in some const locals

   408   HeapWord* const start = mr.start();

   409   HeapWord* const end = mr.end();

   410 

   411   // We used to use "block_start_careful" here.  But we're actually happy

   412   // to update the BOT while we do this...

   413   HeapWord* cur = block_start(start);

   414   assert(cur <= start, "Postcondition");

   415 

   416   oop obj;

   417 

   418   HeapWord* next = cur;

   419   do {

   420     cur = next;

   421     obj = oop(cur);

   422     if (obj->klass_or_null() == NULL) {

   423       // Ran into an unparseable point.

   424       return cur;

   425     }

   426     // Otherwise...

   427     next = cur + block_size(cur);

   428   } while (next <= start);

   429 

   430   // If we finish the above loop...We have a parseable object that

   431   // begins on or before the start of the memory region, and ends

   432   // inside or spans the entire region.

   433   assert(cur <= start, "Loop postcondition");

   434   assert(obj->klass_or_null() != NULL, "Loop postcondition");

   435 

   436   do {

   437     obj = oop(cur);

   438     assert((cur + block_size(cur)) > (HeapWord*)obj, "Loop invariant");

   439     if (obj->klass_or_null() == NULL) {

   440       // Ran into an unparseable point.

   441       return cur;

   442     }

   443 

   444     // Advance the current pointer. "obj" still points to the object to iterate.

   445     cur = cur + block_size(cur);

   446 

   447     if (!g1h->is_obj_dead(obj)) {

   448       // Non-objArrays are sometimes marked imprecise at the object start. We

   449       // always need to iterate over them in full.

   450       // We only iterate over object arrays in full if they are completely contained

   451       // in the memory region.

   452       if (!obj->is_objArray() || (((HeapWord*)obj) >= start && cur <= end)) {

   453         obj->oop_iterate(cl);

   454       } else {

   455         obj->oop_iterate(cl, mr);

   456       }

   457     }

   458   } while (cur < end);

   459 

   460   return NULL;

   461 }

   462 

   463 // Code roots support

   464 

   465 void HeapRegion::add_strong_code_root(nmethod* nm) {

   466   HeapRegionRemSet* hrrs = rem_set();

   467   hrrs->add_strong_code_root(nm);

   468 }

   469 

   470 void HeapRegion::add_strong_code_root_locked(nmethod* nm) {

   471   assert_locked_or_safepoint(CodeCache_lock);

   472   HeapRegionRemSet* hrrs = rem_set();

   473   hrrs->add_strong_code_root_locked(nm);

   474 }

   475 

   476 void HeapRegion::remove_strong_code_root(nmethod* nm) {

   477   HeapRegionRemSet* hrrs = rem_set();

   478   hrrs->remove_strong_code_root(nm);

   479 }

   480 

   481 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const {

   482   HeapRegionRemSet* hrrs = rem_set();

   483   hrrs->strong_code_roots_do(blk);

   484 }

   485 

   486 class VerifyStrongCodeRootOopClosure: public OopClosure {

   487   const HeapRegion* _hr;

   488   nmethod* _nm;

   489   bool _failures;

   490   bool _has_oops_in_region;

   491 

   492   template <class T> void do_oop_work(T* p) {

   493     T heap_oop = oopDesc::load_heap_oop(p);

   494     if (!oopDesc::is_null(heap_oop)) {

   495       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);

   496 

   497       // Note: not all the oops embedded in the nmethod are in the

   498       // current region. We only look at those which are.

   499       if (_hr->is_in(obj)) {

   500         // Object is in the region. Check that its less than top

   501         if (_hr->top() <= (HeapWord*)obj) {

   502           // Object is above top

   503           gclog_or_tty->print_cr("Object "PTR_FORMAT" in region "

   504                                  "["PTR_FORMAT", "PTR_FORMAT") is above "

   505                                  "top "PTR_FORMAT,

   506                                  p2i(obj), p2i(_hr->bottom()), p2i(_hr->end()), p2i(_hr->top()));

   507           _failures = true;

   508           return;

   509         }

   510         // Nmethod has at least one oop in the current region

   511         _has_oops_in_region = true;

   512       }

   513     }

   514   }

   515 

   516 public:

   517   VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm):

   518     _hr(hr), _failures(false), _has_oops_in_region(false) {}

   519 

   520   void do_oop(narrowOop* p) { do_oop_work(p); }

   521   void do_oop(oop* p)       { do_oop_work(p); }

   522 

   523   bool failures()           { return _failures; }

   524   bool has_oops_in_region() { return _has_oops_in_region; }

   525 };

   526 

   527 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure {

   528   const HeapRegion* _hr;

   529   bool _failures;

   530 public:

   531   VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) :

   532     _hr(hr), _failures(false) {}

   533 

   534   void do_code_blob(CodeBlob* cb) {

   535     nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();

   536     if (nm != NULL) {

   537       // Verify that the nemthod is live

   538       if (!nm->is_alive()) {

   539         gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has dead nmethod "

   540                                PTR_FORMAT" in its strong code roots",

   541                                p2i(_hr->bottom()), p2i(_hr->end()), p2i(nm));

   542         _failures = true;

   543       } else {

   544         VerifyStrongCodeRootOopClosure oop_cl(_hr, nm);

   545         nm->oops_do(&oop_cl);

   546         if (!oop_cl.has_oops_in_region()) {

   547           gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has nmethod "

   548                                  PTR_FORMAT" in its strong code roots "

   549                                  "with no pointers into region",

   550                                  p2i(_hr->bottom()), p2i(_hr->end()), p2i(nm));

   551           _failures = true;

   552         } else if (oop_cl.failures()) {

   553           gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has other "

   554                                  "failures for nmethod "PTR_FORMAT,

   555                                  p2i(_hr->bottom()), p2i(_hr->end()), p2i(nm));

   556           _failures = true;

   557         }

   558       }

   559     }

   560   }

   561 

   562   bool failures()       { return _failures; }

   563 };

   564 

   565 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const {

   566   if (!G1VerifyHeapRegionCodeRoots) {

   567     // We're not verifying code roots.

   568     return;

   569   }

   570   if (vo == VerifyOption_G1UseMarkWord) {

   571     // Marking verification during a full GC is performed after class

   572     // unloading, code cache unloading, etc so the strong code roots

   573     // attached to each heap region are in an inconsistent state. They won't

   574     // be consistent until the strong code roots are rebuilt after the

   575     // actual GC. Skip verifying the strong code roots in this particular

   576     // time.

   577     assert(VerifyDuringGC, "only way to get here");

   578     return;

   579   }

   580 

   581   HeapRegionRemSet* hrrs = rem_set();

   582   size_t strong_code_roots_length = hrrs->strong_code_roots_list_length();

   583 

   584   // if this region is empty then there should be no entries

   585   // on its strong code root list

   586   if (is_empty()) {

   587     if (strong_code_roots_length > 0) {

   588       gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is empty "

   589                              "but has "SIZE_FORMAT" code root entries",

   590                              p2i(bottom()), p2i(end()), strong_code_roots_length);

   591       *failures = true;

   592     }

   593     return;

   594   }

   595 

   596   if (is_continues_humongous()) {

   597     if (strong_code_roots_length > 0) {

   598       gclog_or_tty->print_cr("region "HR_FORMAT" is a continuation of a humongous "

   599                              "region but has "SIZE_FORMAT" code root entries",

   600                              HR_FORMAT_PARAMS(this), strong_code_roots_length);

   601       *failures = true;

   602     }

   603     return;

   604   }

   605 

   606   VerifyStrongCodeRootCodeBlobClosure cb_cl(this);

   607   strong_code_roots_do(&cb_cl);

   608 

   609   if (cb_cl.failures()) {

   610     *failures = true;

   611   }

   612 }

   613 

   614 void HeapRegion::print() const { print_on(gclog_or_tty); }

   615 void HeapRegion::print_on(outputStream* st) const {

   616   st->print("AC%4u", allocation_context());

   617 

   618   st->print(" %2s", get_short_type_str());

   619   if (in_collection_set())

   620     st->print(" CS");

   621   else

   622     st->print("   ");

   623   st->print(" TS %5d", _gc_time_stamp);

   624   st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT,

   625             p2i(prev_top_at_mark_start()), p2i(next_top_at_mark_start()));

   626   G1OffsetTableContigSpace::print_on(st);

   627 }

   628 

   629 class VerifyLiveClosure: public OopClosure {

   630 private:

   631   G1CollectedHeap* _g1h;

   632   CardTableModRefBS* _bs;

   633   oop _containing_obj;

   634   bool _failures;

   635   int _n_failures;

   636   VerifyOption _vo;

   637 public:

   638   // _vo == UsePrevMarking -> use "prev" marking information,

   639   // _vo == UseNextMarking -> use "next" marking information,

   640   // _vo == UseMarkWord    -> use mark word from object header.

   641   VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) :

   642     _g1h(g1h), _bs(barrier_set_cast<CardTableModRefBS>(g1h->barrier_set())),

   643     _containing_obj(NULL), _failures(false), _n_failures(0), _vo(vo)

   644   { }

   645 

   646   void set_containing_obj(oop obj) {

   647     _containing_obj = obj;

   648   }

   649 

   650   bool failures() { return _failures; }

   651   int n_failures() { return _n_failures; }

   652 

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

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

   655 

   656   void print_object(outputStream* out, oop obj) {

   657 #ifdef PRODUCT

   658     Klass* k = obj->klass();

   659     const char* class_name = InstanceKlass::cast(k)->external_name();

   660     out->print_cr("class name %s", class_name);

   661 #else // PRODUCT

   662     obj->print_on(out);

   663 #endif // PRODUCT

   664   }

   665 

   666   template <class T>

   667   void do_oop_work(T* p) {

   668     assert(_containing_obj != NULL, "Precondition");

   669     assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),

   670            "Precondition");

   671     T heap_oop = oopDesc::load_heap_oop(p);

   672     if (!oopDesc::is_null(heap_oop)) {

   673       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);

   674       bool failed = false;

   675       if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) {

   676         MutexLockerEx x(ParGCRareEvent_lock,

   677                         Mutex::_no_safepoint_check_flag);

   678 

   679         if (!_failures) {

   680           gclog_or_tty->cr();

   681           gclog_or_tty->print_cr("----------");

   682         }

   683         if (!_g1h->is_in_closed_subset(obj)) {

   684           HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);

   685           gclog_or_tty->print_cr("Field "PTR_FORMAT

   686                                  " of live obj "PTR_FORMAT" in region "

   687                                  "["PTR_FORMAT", "PTR_FORMAT")",

   688                                  p2i(p), p2i(_containing_obj),

   689                                  p2i(from->bottom()), p2i(from->end()));

   690           print_object(gclog_or_tty, _containing_obj);

   691           gclog_or_tty->print_cr("points to obj "PTR_FORMAT" not in the heap",

   692                                  p2i(obj));

   693         } else {

   694           HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);

   695           HeapRegion* to   = _g1h->heap_region_containing((HeapWord*)obj);

   696           gclog_or_tty->print_cr("Field "PTR_FORMAT

   697                                  " of live obj "PTR_FORMAT" in region "

   698                                  "["PTR_FORMAT", "PTR_FORMAT")",

   699                                  p2i(p), p2i(_containing_obj),

   700                                  p2i(from->bottom()), p2i(from->end()));

   701           print_object(gclog_or_tty, _containing_obj);

   702           gclog_or_tty->print_cr("points to dead obj "PTR_FORMAT" in region "

   703                                  "["PTR_FORMAT", "PTR_FORMAT")",

   704                                  p2i(obj), p2i(to->bottom()), p2i(to->end()));

   705           print_object(gclog_or_tty, obj);

   706         }

   707         gclog_or_tty->print_cr("----------");

   708         gclog_or_tty->flush();

   709         _failures = true;

   710         failed = true;

   711         _n_failures++;

   712       }

   713 

   714       if (!_g1h->full_collection() || G1VerifyRSetsDuringFullGC) {

   715         HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);

   716         HeapRegion* to   = _g1h->heap_region_containing(obj);

   717         if (from != NULL && to != NULL &&

   718             from != to &&

   719             !to->is_humongous()) {

   720           jbyte cv_obj = *_bs->byte_for_const(_containing_obj);

   721           jbyte cv_field = *_bs->byte_for_const(p);

   722           const jbyte dirty = CardTableModRefBS::dirty_card_val();

   723 

   724           bool is_bad = !(from->is_young()

   725                           || to->rem_set()->contains_reference(p)

   726                           || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed

   727                               (_containing_obj->is_objArray() ?

   728                                   cv_field == dirty

   729                                : cv_obj == dirty || cv_field == dirty));

   730           if (is_bad) {

   731             MutexLockerEx x(ParGCRareEvent_lock,

   732                             Mutex::_no_safepoint_check_flag);

   733 

   734             if (!_failures) {

   735               gclog_or_tty->cr();

   736               gclog_or_tty->print_cr("----------");

   737             }

   738             gclog_or_tty->print_cr("Missing rem set entry:");

   739             gclog_or_tty->print_cr("Field "PTR_FORMAT" "

   740                                    "of obj "PTR_FORMAT", "

   741                                    "in region "HR_FORMAT,

   742                                    p2i(p), p2i(_containing_obj),

   743                                    HR_FORMAT_PARAMS(from));

   744             _containing_obj->print_on(gclog_or_tty);

   745             gclog_or_tty->print_cr("points to obj "PTR_FORMAT" "

   746                                    "in region "HR_FORMAT,

   747                                    p2i(obj),

   748                                    HR_FORMAT_PARAMS(to));

   749             obj->print_on(gclog_or_tty);

   750             gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",

   751                           cv_obj, cv_field);

   752             gclog_or_tty->print_cr("----------");

   753             gclog_or_tty->flush();

   754             _failures = true;

   755             if (!failed) _n_failures++;

   756           }

   757         }

   758       }

   759     }

   760   }

   761 };

   762 

   763 // This really ought to be commoned up into OffsetTableContigSpace somehow.

   764 // We would need a mechanism to make that code skip dead objects.

   765 

   766 void HeapRegion::verify(VerifyOption vo,

   767                         bool* failures) const {

   768   G1CollectedHeap* g1 = G1CollectedHeap::heap();

   769   *failures = false;

   770   HeapWord* p = bottom();

   771   HeapWord* prev_p = NULL;

   772   VerifyLiveClosure vl_cl(g1, vo);

   773   bool is_region_humongous = is_humongous();

   774   size_t object_num = 0;

   775   while (p < top()) {

   776     oop obj = oop(p);

   777     size_t obj_size = block_size(p);

   778     object_num += 1;

   779 

   780     if (is_region_humongous != g1->is_humongous(obj_size) &&

   781         !g1->is_obj_dead(obj, this)) { // Dead objects may have bigger block_size since they span several objects.

   782       gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size ("

   783                              SIZE_FORMAT" words) in a %shumongous region",

   784                              p2i(p), g1->is_humongous(obj_size) ? "" : "non-",

   785                              obj_size, is_region_humongous ? "" : "non-");

   786        *failures = true;

   787        return;

   788     }

   789 

   790     if (!g1->is_obj_dead_cond(obj, this, vo)) {

   791       if (obj->is_oop()) {

   792         Klass* klass = obj->klass();

   793         bool is_metaspace_object = Metaspace::contains(klass) ||

   794                                    (vo == VerifyOption_G1UsePrevMarking &&

   795                                    ClassLoaderDataGraph::unload_list_contains(klass));

   796         if (!is_metaspace_object) {

   797           gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "

   798                                  "not metadata", p2i(klass), p2i(obj));

   799           *failures = true;

   800           return;

   801         } else if (!klass->is_klass()) {

   802           gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "

   803                                  "not a klass", p2i(klass), p2i(obj));

   804           *failures = true;

   805           return;

   806         } else {

   807           vl_cl.set_containing_obj(obj);

   808           obj->oop_iterate_no_header(&vl_cl);

   809           if (vl_cl.failures()) {

   810             *failures = true;

   811           }

   812           if (G1MaxVerifyFailures >= 0 &&

   813               vl_cl.n_failures() >= G1MaxVerifyFailures) {

   814             return;

   815           }

   816         }

   817       } else {

   818         gclog_or_tty->print_cr(PTR_FORMAT" no an oop", p2i(obj));

   819         *failures = true;

   820         return;

   821       }

   822     }

   823     prev_p = p;

   824     p += obj_size;

   825   }

   826 

   827   if (!is_young() && !is_empty()) {

   828     _offsets.verify();

   829   }

   830 

   831   if (p != top()) {

   832     gclog_or_tty->print_cr("end of last object "PTR_FORMAT" "

   833                            "does not match top "PTR_FORMAT, p2i(p), p2i(top()));

   834     *failures = true;

   835     return;

   836   }

   837 

   838   HeapWord* the_end = end();

   839   assert(p == top(), "it should still hold");

   840   // Do some extra BOT consistency checking for addresses in the

   841   // range [top, end). BOT look-ups in this range should yield

   842   // top. No point in doing that if top == end (there's nothing there).

   843   if (p < the_end) {

   844     // Look up top

   845     HeapWord* addr_1 = p;

   846     HeapWord* b_start_1 = _offsets.block_start_const(addr_1);

   847     if (b_start_1 != p) {

   848       gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" "

   849                              " yielded "PTR_FORMAT", expecting "PTR_FORMAT,

   850                              p2i(addr_1), p2i(b_start_1), p2i(p));

   851       *failures = true;

   852       return;

   853     }

   854 

   855     // Look up top + 1

   856     HeapWord* addr_2 = p + 1;

   857     if (addr_2 < the_end) {

   858       HeapWord* b_start_2 = _offsets.block_start_const(addr_2);

   859       if (b_start_2 != p) {

   860         gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" "

   861                                " yielded "PTR_FORMAT", expecting "PTR_FORMAT,

   862                                p2i(addr_2), p2i(b_start_2), p2i(p));

   863         *failures = true;

   864         return;

   865       }

   866     }

   867 

   868     // Look up an address between top and end

   869     size_t diff = pointer_delta(the_end, p) / 2;

   870     HeapWord* addr_3 = p + diff;

   871     if (addr_3 < the_end) {

   872       HeapWord* b_start_3 = _offsets.block_start_const(addr_3);

   873       if (b_start_3 != p) {

   874         gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" "

   875                                " yielded "PTR_FORMAT", expecting "PTR_FORMAT,

   876                                p2i(addr_3), p2i(b_start_3), p2i(p));

   877         *failures = true;

   878         return;

   879       }

   880     }

   881 

   882     // Look up end - 1

   883     HeapWord* addr_4 = the_end - 1;

   884     HeapWord* b_start_4 = _offsets.block_start_const(addr_4);

   885     if (b_start_4 != p) {

   886       gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" "

   887                              " yielded "PTR_FORMAT", expecting "PTR_FORMAT,

   888                              p2i(addr_4), p2i(b_start_4), p2i(p));

   889       *failures = true;

   890       return;

   891     }

   892   }

   893 

   894   if (is_region_humongous && object_num > 1) {

   895     gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "

   896                            "but has "SIZE_FORMAT", objects",

   897                            p2i(bottom()), p2i(end()), object_num);

   898     *failures = true;

   899     return;

   900   }

   901 

   902   verify_strong_code_roots(vo, failures);

   903 }

   904 

   905 void HeapRegion::verify() const {

   906   bool dummy = false;

   907   verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy);

   908 }

   909 

   910 void HeapRegion::prepare_for_compaction(CompactPoint* cp) {

   911   scan_and_forward(this, cp);

   912 }

   913 

   914 // G1OffsetTableContigSpace code; copied from space.cpp.  Hope this can go

   915 // away eventually.

   916 

   917 void G1OffsetTableContigSpace::clear(bool mangle_space) {

   918   set_top(bottom());

   919   _scan_top = bottom();

   920   CompactibleSpace::clear(mangle_space);

   921   reset_bot();

   922 }

   923 

   924 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {

   925   Space::set_bottom(new_bottom);

   926   _offsets.set_bottom(new_bottom);

   927 }

   928 

   929 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {

   930   Space::set_end(new_end);

   931   _offsets.resize(new_end - bottom());

   932 }

   933 

   934 #ifndef PRODUCT

   935 void G1OffsetTableContigSpace::mangle_unused_area() {

   936   mangle_unused_area_complete();

   937 }

   938 

   939 void G1OffsetTableContigSpace::mangle_unused_area_complete() {

   940   SpaceMangler::mangle_region(MemRegion(top(), end()));

   941 }

   942 #endif

   943 

   944 void G1OffsetTableContigSpace::print() const {

   945   print_short();

   946   gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "

   947                 INTPTR_FORMAT ", " INTPTR_FORMAT ")",

   948                 p2i(bottom()), p2i(top()), p2i(_offsets.threshold()), p2i(end()));

   949 }

   950 

   951 HeapWord* G1OffsetTableContigSpace::initialize_threshold() {

   952   return _offsets.initialize_threshold();

   953 }

   954 

   955 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start,

   956                                                     HeapWord* end) {

   957   _offsets.alloc_block(start, end);

   958   return _offsets.threshold();

   959 }

   960 

   961 HeapWord* G1OffsetTableContigSpace::scan_top() const {

   962   G1CollectedHeap* g1h = G1CollectedHeap::heap();

   963   HeapWord* local_top = top();

   964   OrderAccess::loadload();

   965   const unsigned local_time_stamp = _gc_time_stamp;

   966   assert(local_time_stamp <= g1h->get_gc_time_stamp(), "invariant");

   967   if (local_time_stamp < g1h->get_gc_time_stamp()) {

   968     return local_top;

   969   } else {

   970     return _scan_top;

   971   }

   972 }

   973 

   974 void G1OffsetTableContigSpace::record_timestamp() {

   975   G1CollectedHeap* g1h = G1CollectedHeap::heap();

   976   unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();

   977 

   978   if (_gc_time_stamp < curr_gc_time_stamp) {

   979     // Setting the time stamp here tells concurrent readers to look at

   980     // scan_top to know the maximum allowed address to look at.

   981 

   982     // scan_top should be bottom for all regions except for the

   983     // retained old alloc region which should have scan_top == top

   984     HeapWord* st = _scan_top;

   985     guarantee(st == _bottom || st == _top, "invariant");

   986 

   987     _gc_time_stamp = curr_gc_time_stamp;

   988   }

   989 }

   990 

   991 void G1OffsetTableContigSpace::record_retained_region() {

   992   // scan_top is the maximum address where it's safe for the next gc to

   993   // scan this region.

   994   _scan_top = top();

   995 }

   996 

   997 void G1OffsetTableContigSpace::safe_object_iterate(ObjectClosure* blk) {

   998   object_iterate(blk);

   999 }

  1000 

  1001 void G1OffsetTableContigSpace::object_iterate(ObjectClosure* blk) {

  1002   HeapWord* p = bottom();

  1003   while (p < top()) {

  1004     if (block_is_obj(p)) {

  1005       blk->do_object(oop(p));

  1006     }

  1007     p += block_size(p);

  1008   }

  1009 }

  1010 

  1011 G1OffsetTableContigSpace::

  1012 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,

  1013                          MemRegion mr) :

  1014   _offsets(sharedOffsetArray, mr),

  1015   _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),

  1016   _gc_time_stamp(0)

  1017 {

  1018   _offsets.set_space(this);

  1019 }

  1020 

  1021 void G1OffsetTableContigSpace::initialize(MemRegion mr, bool clear_space, bool mangle_space) {

  1022   CompactibleSpace::initialize(mr, clear_space, mangle_space);

  1023   _top = bottom();

  1024   _scan_top = bottom();

  1025   set_saved_mark_word(NULL);

  1026   reset_bot();

  1027 }

  1028