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))) {
  71     oop_size = oop(cur)->oop_iterate_size(_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)) {
  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))) {
  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 size_t HeapRegion::min_region_size_in_words() {
 107   return HeapRegionBounds::min_size() >> LogHeapWordSize;
 108 }
 109 
 110 void HeapRegion::setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size) {
 111   size_t region_size = G1HeapRegionSize;
 112   if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {
 113     size_t average_heap_size = (initial_heap_size + max_heap_size) / 2;
 114     region_size = MAX2(average_heap_size / HeapRegionBounds::target_number(),
 115                        HeapRegionBounds::min_size());
 116   }
 117 
 118   int region_size_log = log2_long((jlong) region_size);
 119   // Recalculate the region size to make sure it's a power of
 120   // 2. This means that region_size is the largest power of 2 that's
 121   // <= what we've calculated so far.
 122   region_size = ((size_t)1 << region_size_log);
 123 
 124   // Now make sure that we don't go over or under our limits.
 125   if (region_size < HeapRegionBounds::min_size()) {
 126     region_size = HeapRegionBounds::min_size();
 127   } else if (region_size > HeapRegionBounds::max_size()) {
 128     region_size = HeapRegionBounds::max_size();
 129   }
 130 
 131   // And recalculate the log.
 132   region_size_log = log2_long((jlong) region_size);
 133 
 134   // Now, set up the globals.
 135   guarantee(LogOfHRGrainBytes == 0, "we should only set it once");
 136   LogOfHRGrainBytes = region_size_log;
 137 
 138   guarantee(LogOfHRGrainWords == 0, "we should only set it once");
 139   LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize;
 140 
 141   guarantee(GrainBytes == 0, "we should only set it once");
 142   // The cast to int is safe, given that we've bounded region_size by
 143   // MIN_REGION_SIZE and MAX_REGION_SIZE.
 144   GrainBytes = region_size;
 145 
 146   guarantee(GrainWords == 0, "we should only set it once");
 147   GrainWords = GrainBytes >> LogHeapWordSize;
 148   guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity");
 149 
 150   guarantee(CardsPerRegion == 0, "we should only set it once");
 151   CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift;
 152 }
 153 
 154 void HeapRegion::reset_after_compaction() {
 155   G1OffsetTableContigSpace::reset_after_compaction();
 156   // After a compaction the mark bitmap is invalid, so we must
 157   // treat all objects as being inside the unmarked area.
 158   zero_marked_bytes();
 159   init_top_at_mark_start();
 160 }
 161 
 162 void HeapRegion::hr_clear(bool par, bool clear_space, bool locked) {
 163   assert(_humongous_start_region == NULL,
 164          "we should have already filtered out humongous regions");
 165   assert(!in_collection_set(),
 166          "Should not clear heap region %u in the collection set", hrm_index());
 167 
 168   set_allocation_context(AllocationContext::system());
 169   set_young_index_in_cset(-1);
 170   uninstall_surv_rate_group();
 171   set_free();
 172   reset_pre_dummy_top();
 173 
 174   if (!par) {
 175     // If this is parallel, this will be done later.
 176     HeapRegionRemSet* hrrs = rem_set();
 177     if (locked) {
 178       hrrs->clear_locked();
 179     } else {
 180       hrrs->clear();
 181     }
 182   }
 183   zero_marked_bytes();
 184 
 185   _offsets.resize(HeapRegion::GrainWords);
 186   init_top_at_mark_start();
 187   if (clear_space) clear(SpaceDecorator::Mangle);
 188 }
 189 
 190 void HeapRegion::par_clear() {
 191   assert(used() == 0, "the region should have been already cleared");
 192   assert(capacity() == HeapRegion::GrainBytes, "should be back to normal");
 193   HeapRegionRemSet* hrrs = rem_set();
 194   hrrs->clear();
 195   CardTableModRefBS* ct_bs =
 196     barrier_set_cast<CardTableModRefBS>(G1CollectedHeap::heap()->barrier_set());
 197   ct_bs->clear(MemRegion(bottom(), end()));
 198 }
 199 
 200 void HeapRegion::calc_gc_efficiency() {
 201   // GC efficiency is the ratio of how much space would be
 202   // reclaimed over how long we predict it would take to reclaim it.
 203   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 204   G1CollectorPolicy* g1p = g1h->g1_policy();
 205 
 206   // Retrieve a prediction of the elapsed time for this region for
 207   // a mixed gc because the region will only be evacuated during a
 208   // mixed gc.
 209   double region_elapsed_time_ms =
 210     g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */);
 211   _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms;
 212 }
 213 
 214 void HeapRegion::set_starts_humongous(HeapWord* obj_top) {
 215   assert(!is_humongous(), "sanity / pre-condition");
 216   assert(top() == bottom(), "should be empty");
 217 
 218   _type.set_starts_humongous();
 219   _humongous_start_region = this;
 220 
 221   _offsets.set_for_starts_humongous(obj_top);
 222 }
 223 
 224 void HeapRegion::set_continues_humongous(HeapRegion* first_hr) {
 225   assert(!is_humongous(), "sanity / pre-condition");
 226   assert(top() == bottom(), "should be empty");
 227   assert(first_hr->is_starts_humongous(), "pre-condition");
 228 
 229   _type.set_continues_humongous();
 230   _humongous_start_region = first_hr;
 231 }
 232 
 233 void HeapRegion::clear_humongous() {
 234   assert(is_humongous(), "pre-condition");
 235 
 236   assert(capacity() == HeapRegion::GrainBytes, "pre-condition");
 237   _humongous_start_region = NULL;
 238 }
 239 
 240 HeapRegion::HeapRegion(uint hrm_index,
 241                        G1BlockOffsetSharedArray* sharedOffsetArray,
 242                        MemRegion mr) :
 243     G1OffsetTableContigSpace(sharedOffsetArray, mr),
 244     _hrm_index(hrm_index),
 245     _allocation_context(AllocationContext::system()),
 246     _humongous_start_region(NULL),
 247     _next_in_special_set(NULL),
 248     _evacuation_failed(false),
 249     _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0),
 250     _next_young_region(NULL),
 251     _next_dirty_cards_region(NULL), _next(NULL), _prev(NULL),
 252 #ifdef ASSERT
 253     _containing_set(NULL),
 254 #endif // ASSERT
 255      _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),
 256     _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),
 257     _predicted_bytes_to_copy(0)
 258 {
 259   _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);
 260   assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
 261 
 262   initialize(mr);
 263 }
 264 
 265 void HeapRegion::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
 266   assert(_rem_set->is_empty(), "Remembered set must be empty");
 267 
 268   G1OffsetTableContigSpace::initialize(mr, clear_space, mangle_space);
 269 
 270   hr_clear(false /*par*/, false /*clear_space*/);
 271   set_top(bottom());
 272   record_timestamp();
 273 }
 274 
 275 CompactibleSpace* HeapRegion::next_compaction_space() const {
 276   return G1CollectedHeap::heap()->next_compaction_region(this);
 277 }
 278 
 279 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,
 280                                                     bool during_conc_mark) {
 281   // We always recreate the prev marking info and we'll explicitly
 282   // mark all objects we find to be self-forwarded on the prev
 283   // bitmap. So all objects need to be below PTAMS.
 284   _prev_marked_bytes = 0;
 285 
 286   if (during_initial_mark) {
 287     // During initial-mark, we'll also explicitly mark all objects
 288     // we find to be self-forwarded on the next bitmap. So all
 289     // objects need to be below NTAMS.
 290     _next_top_at_mark_start = top();
 291     _next_marked_bytes = 0;
 292   } else if (during_conc_mark) {
 293     // During concurrent mark, all objects in the CSet (including
 294     // the ones we find to be self-forwarded) are implicitly live.
 295     // So all objects need to be above NTAMS.
 296     _next_top_at_mark_start = bottom();
 297     _next_marked_bytes = 0;
 298   }
 299 }
 300 
 301 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark,
 302                                                   bool during_conc_mark,
 303                                                   size_t marked_bytes) {
 304   assert(marked_bytes <= used(),
 305          "marked: " SIZE_FORMAT " used: " SIZE_FORMAT, marked_bytes, used());
 306   _prev_top_at_mark_start = top();
 307   _prev_marked_bytes = marked_bytes;
 308 }
 309 
 310 HeapWord*
 311 HeapRegion::object_iterate_mem_careful(MemRegion mr,
 312                                                  ObjectClosure* cl) {
 313   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 314   // We used to use "block_start_careful" here.  But we're actually happy
 315   // to update the BOT while we do this...
 316   HeapWord* cur = block_start(mr.start());
 317   mr = mr.intersection(used_region());
 318   if (mr.is_empty()) return NULL;
 319   // Otherwise, find the obj that extends onto mr.start().
 320 
 321   assert(cur <= mr.start()
 322          && (oop(cur)->klass_or_null() == NULL ||
 323              cur + oop(cur)->size() > mr.start()),
 324          "postcondition of block_start");
 325   oop obj;
 326   while (cur < mr.end()) {
 327     obj = oop(cur);
 328     if (obj->klass_or_null() == NULL) {
 329       // Ran into an unparseable point.
 330       return cur;
 331     } else if (!g1h->is_obj_dead(obj)) {
 332       cl->do_object(obj);
 333     }
 334     cur += block_size(cur);
 335   }
 336   return NULL;
 337 }
 338 
 339 HeapWord*
 340 HeapRegion::
 341 oops_on_card_seq_iterate_careful(MemRegion mr,
 342                                  FilterOutOfRegionClosure* cl,
 343                                  bool filter_young,
 344                                  jbyte* card_ptr) {
 345   // Currently, we should only have to clean the card if filter_young
 346   // is true and vice versa.
 347   if (filter_young) {
 348     assert(card_ptr != NULL, "pre-condition");
 349   } else {
 350     assert(card_ptr == NULL, "pre-condition");
 351   }
 352   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 353 
 354   // If we're within a stop-world GC, then we might look at a card in a
 355   // GC alloc region that extends onto a GC LAB, which may not be
 356   // parseable.  Stop such at the "scan_top" of the region.
 357   if (g1h->is_gc_active()) {
 358     mr = mr.intersection(MemRegion(bottom(), scan_top()));
 359   } else {
 360     mr = mr.intersection(used_region());
 361   }
 362   if (mr.is_empty()) return NULL;
 363   // Otherwise, find the obj that extends onto mr.start().
 364 
 365   // The intersection of the incoming mr (for the card) and the
 366   // allocated part of the region is non-empty. This implies that
 367   // we have actually allocated into this region. The code in
 368   // G1CollectedHeap.cpp that allocates a new region sets the
 369   // is_young tag on the region before allocating. Thus we
 370   // safely know if this region is young.
 371   if (is_young() && filter_young) {
 372     return NULL;
 373   }
 374 
 375   assert(!is_young(), "check value of filter_young");
 376 
 377   // We can only clean the card here, after we make the decision that
 378   // the card is not young. And we only clean the card if we have been
 379   // asked to (i.e., card_ptr != NULL).
 380   if (card_ptr != NULL) {
 381     *card_ptr = CardTableModRefBS::clean_card_val();
 382     // We must complete this write before we do any of the reads below.
 383     OrderAccess::storeload();
 384   }
 385 
 386   // Cache the boundaries of the memory region in some const locals
 387   HeapWord* const start = mr.start();
 388   HeapWord* const end = mr.end();
 389 
 390   // We used to use "block_start_careful" here.  But we're actually happy
 391   // to update the BOT while we do this...
 392   HeapWord* cur = block_start(start);
 393   assert(cur <= start, "Postcondition");
 394 
 395   oop obj;
 396 
 397   HeapWord* next = cur;
 398   do {
 399     cur = next;
 400     obj = oop(cur);
 401     if (obj->klass_or_null() == NULL) {
 402       // Ran into an unparseable point.
 403       return cur;
 404     }
 405     // Otherwise...
 406     next = cur + block_size(cur);
 407   } while (next <= start);
 408 
 409   // If we finish the above loop...We have a parseable object that
 410   // begins on or before the start of the memory region, and ends
 411   // inside or spans the entire region.
 412   assert(cur <= start, "Loop postcondition");
 413   assert(obj->klass_or_null() != NULL, "Loop postcondition");
 414 
 415   do {
 416     obj = oop(cur);
 417     assert((cur + block_size(cur)) > (HeapWord*)obj, "Loop invariant");
 418     if (obj->klass_or_null() == NULL) {
 419       // Ran into an unparseable point.
 420       return cur;
 421     }
 422 
 423     // Advance the current pointer. "obj" still points to the object to iterate.
 424     cur = cur + block_size(cur);
 425 
 426     if (!g1h->is_obj_dead(obj)) {
 427       // Non-objArrays are sometimes marked imprecise at the object start. We
 428       // always need to iterate over them in full.
 429       // We only iterate over object arrays in full if they are completely contained
 430       // in the memory region.
 431       if (!obj->is_objArray() || (((HeapWord*)obj) >= start && cur <= end)) {
 432         obj->oop_iterate(cl);
 433       } else {
 434         obj->oop_iterate(cl, mr);
 435       }
 436     }
 437   } while (cur < end);
 438 
 439   return NULL;
 440 }
 441 
 442 // Code roots support
 443 
 444 void HeapRegion::add_strong_code_root(nmethod* nm) {
 445   HeapRegionRemSet* hrrs = rem_set();
 446   hrrs->add_strong_code_root(nm);
 447 }
 448 
 449 void HeapRegion::add_strong_code_root_locked(nmethod* nm) {
 450   assert_locked_or_safepoint(CodeCache_lock);
 451   HeapRegionRemSet* hrrs = rem_set();
 452   hrrs->add_strong_code_root_locked(nm);
 453 }
 454 
 455 void HeapRegion::remove_strong_code_root(nmethod* nm) {
 456   HeapRegionRemSet* hrrs = rem_set();
 457   hrrs->remove_strong_code_root(nm);
 458 }
 459 
 460 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const {
 461   HeapRegionRemSet* hrrs = rem_set();
 462   hrrs->strong_code_roots_do(blk);
 463 }
 464 
 465 class VerifyStrongCodeRootOopClosure: public OopClosure {
 466   const HeapRegion* _hr;
 467   nmethod* _nm;
 468   bool _failures;
 469   bool _has_oops_in_region;
 470 
 471   template <class T> void do_oop_work(T* p) {
 472     T heap_oop = oopDesc::load_heap_oop(p);
 473     if (!oopDesc::is_null(heap_oop)) {
 474       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
 475 
 476       // Note: not all the oops embedded in the nmethod are in the
 477       // current region. We only look at those which are.
 478       if (_hr->is_in(obj)) {
 479         // Object is in the region. Check that its less than top
 480         if (_hr->top() <= (HeapWord*)obj) {
 481           // Object is above top
 482           gclog_or_tty->print_cr("Object " PTR_FORMAT " in region "
 483                                  "[" PTR_FORMAT ", " PTR_FORMAT ") is above "
 484                                  "top " PTR_FORMAT,
 485                                  p2i(obj), p2i(_hr->bottom()), p2i(_hr->end()), p2i(_hr->top()));
 486           _failures = true;
 487           return;
 488         }
 489         // Nmethod has at least one oop in the current region
 490         _has_oops_in_region = true;
 491       }
 492     }
 493   }
 494 
 495 public:
 496   VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm):
 497     _hr(hr), _failures(false), _has_oops_in_region(false) {}
 498 
 499   void do_oop(narrowOop* p) { do_oop_work(p); }
 500   void do_oop(oop* p)       { do_oop_work(p); }
 501 
 502   bool failures()           { return _failures; }
 503   bool has_oops_in_region() { return _has_oops_in_region; }
 504 };
 505 
 506 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
 507   const HeapRegion* _hr;
 508   bool _failures;
 509 public:
 510   VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) :
 511     _hr(hr), _failures(false) {}
 512 
 513   void do_code_blob(CodeBlob* cb) {
 514     nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
 515     if (nm != NULL) {
 516       // Verify that the nemthod is live
 517       if (!nm->is_alive()) {
 518         gclog_or_tty->print_cr("region [" PTR_FORMAT "," PTR_FORMAT "] has dead nmethod "
 519                                PTR_FORMAT " in its strong code roots",
 520                                p2i(_hr->bottom()), p2i(_hr->end()), p2i(nm));
 521         _failures = true;
 522       } else {
 523         VerifyStrongCodeRootOopClosure oop_cl(_hr, nm);
 524         nm->oops_do(&oop_cl);
 525         if (!oop_cl.has_oops_in_region()) {
 526           gclog_or_tty->print_cr("region [" PTR_FORMAT "," PTR_FORMAT "] has nmethod "
 527                                  PTR_FORMAT " in its strong code roots "
 528                                  "with no pointers into region",
 529                                  p2i(_hr->bottom()), p2i(_hr->end()), p2i(nm));
 530           _failures = true;
 531         } else if (oop_cl.failures()) {
 532           gclog_or_tty->print_cr("region [" PTR_FORMAT "," PTR_FORMAT "] has other "
 533                                  "failures for nmethod " PTR_FORMAT,
 534                                  p2i(_hr->bottom()), p2i(_hr->end()), p2i(nm));
 535           _failures = true;
 536         }
 537       }
 538     }
 539   }
 540 
 541   bool failures()       { return _failures; }
 542 };
 543 
 544 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const {
 545   if (!G1VerifyHeapRegionCodeRoots) {
 546     // We're not verifying code roots.
 547     return;
 548   }
 549   if (vo == VerifyOption_G1UseMarkWord) {
 550     // Marking verification during a full GC is performed after class
 551     // unloading, code cache unloading, etc so the strong code roots
 552     // attached to each heap region are in an inconsistent state. They won't
 553     // be consistent until the strong code roots are rebuilt after the
 554     // actual GC. Skip verifying the strong code roots in this particular
 555     // time.
 556     assert(VerifyDuringGC, "only way to get here");
 557     return;
 558   }
 559 
 560   HeapRegionRemSet* hrrs = rem_set();
 561   size_t strong_code_roots_length = hrrs->strong_code_roots_list_length();
 562 
 563   // if this region is empty then there should be no entries
 564   // on its strong code root list
 565   if (is_empty()) {
 566     if (strong_code_roots_length > 0) {
 567       gclog_or_tty->print_cr("region [" PTR_FORMAT "," PTR_FORMAT "] is empty "
 568                              "but has " SIZE_FORMAT " code root entries",
 569                              p2i(bottom()), p2i(end()), strong_code_roots_length);
 570       *failures = true;
 571     }
 572     return;
 573   }
 574 
 575   if (is_continues_humongous()) {
 576     if (strong_code_roots_length > 0) {
 577       gclog_or_tty->print_cr("region " HR_FORMAT " is a continuation of a humongous "
 578                              "region but has " SIZE_FORMAT " code root entries",
 579                              HR_FORMAT_PARAMS(this), strong_code_roots_length);
 580       *failures = true;
 581     }
 582     return;
 583   }
 584 
 585   VerifyStrongCodeRootCodeBlobClosure cb_cl(this);
 586   strong_code_roots_do(&cb_cl);
 587 
 588   if (cb_cl.failures()) {
 589     *failures = true;
 590   }
 591 }
 592 
 593 void HeapRegion::print() const { print_on(gclog_or_tty); }
 594 void HeapRegion::print_on(outputStream* st) const {
 595   st->print("AC%4u", allocation_context());
 596 
 597   st->print(" %2s", get_short_type_str());
 598   if (in_collection_set())
 599     st->print(" CS");
 600   else
 601     st->print("   ");
 602   st->print(" TS %5d", _gc_time_stamp);
 603   st->print(" PTAMS " PTR_FORMAT " NTAMS " PTR_FORMAT,
 604             p2i(prev_top_at_mark_start()), p2i(next_top_at_mark_start()));
 605   G1OffsetTableContigSpace::print_on(st);
 606 }
 607 
 608 class VerifyLiveClosure: public OopClosure {
 609 private:
 610   G1CollectedHeap* _g1h;
 611   CardTableModRefBS* _bs;
 612   oop _containing_obj;
 613   bool _failures;
 614   int _n_failures;
 615   VerifyOption _vo;
 616 public:
 617   // _vo == UsePrevMarking -> use "prev" marking information,
 618   // _vo == UseNextMarking -> use "next" marking information,
 619   // _vo == UseMarkWord    -> use mark word from object header.
 620   VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) :
 621     _g1h(g1h), _bs(barrier_set_cast<CardTableModRefBS>(g1h->barrier_set())),
 622     _containing_obj(NULL), _failures(false), _n_failures(0), _vo(vo)
 623   { }
 624 
 625   void set_containing_obj(oop obj) {
 626     _containing_obj = obj;
 627   }
 628 
 629   bool failures() { return _failures; }
 630   int n_failures() { return _n_failures; }
 631 
 632   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
 633   virtual void do_oop(      oop* p) { do_oop_work(p); }
 634 
 635   void print_object(outputStream* out, oop obj) {
 636 #ifdef PRODUCT
 637     Klass* k = obj->klass();
 638     const char* class_name = k->external_name();
 639     out->print_cr("class name %s", class_name);
 640 #else // PRODUCT
 641     obj->print_on(out);
 642 #endif // PRODUCT
 643   }
 644 
 645   template <class T>
 646   void do_oop_work(T* p) {
 647     assert(_containing_obj != NULL, "Precondition");
 648     assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
 649            "Precondition");
 650     T heap_oop = oopDesc::load_heap_oop(p);

 651     if (!oopDesc::is_null(heap_oop)) {
 652       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
 653       bool failed = false;
 654       if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) {
 655         MutexLockerEx x(ParGCRareEvent_lock,
 656                         Mutex::_no_safepoint_check_flag);
 657 
 658         if (!_failures) {
 659           gclog_or_tty->cr();
 660           gclog_or_tty->print_cr("----------");
 661         }

 662         if (!_g1h->is_in_closed_subset(obj)) {
 663           HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
 664           gclog_or_tty->print_cr("Field " PTR_FORMAT
 665                                  " of live obj " PTR_FORMAT " in region "
 666                                  "[" PTR_FORMAT ", " PTR_FORMAT ")",
 667                                  p2i(p), p2i(_containing_obj),
 668                                  p2i(from->bottom()), p2i(from->end()));
 669           print_object(gclog_or_tty, _containing_obj);
 670           gclog_or_tty->print_cr("points to obj " PTR_FORMAT " not in the heap",
 671                                  p2i(obj));
 672         } else {
 673           HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
 674           HeapRegion* to   = _g1h->heap_region_containing((HeapWord*)obj);
 675           gclog_or_tty->print_cr("Field " PTR_FORMAT
 676                                  " of live obj " PTR_FORMAT " in region "
 677                                  "[" PTR_FORMAT ", " PTR_FORMAT ")",
 678                                  p2i(p), p2i(_containing_obj),
 679                                  p2i(from->bottom()), p2i(from->end()));
 680           print_object(gclog_or_tty, _containing_obj);
 681           gclog_or_tty->print_cr("points to dead obj " PTR_FORMAT " in region "
 682                                  "[" PTR_FORMAT ", " PTR_FORMAT ")",
 683                                  p2i(obj), p2i(to->bottom()), p2i(to->end()));
 684           print_object(gclog_or_tty, obj);
 685         }
 686         gclog_or_tty->print_cr("----------");
 687         gclog_or_tty->flush();
 688         _failures = true;
 689         failed = true;
 690         _n_failures++;
 691       }
 692 
 693       if (!_g1h->collector_state()->full_collection() || G1VerifyRSetsDuringFullGC) {
 694         HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
 695         HeapRegion* to   = _g1h->heap_region_containing(obj);
 696         if (from != NULL && to != NULL &&
 697             from != to &&
 698             !to->is_pinned()) {
 699           jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
 700           jbyte cv_field = *_bs->byte_for_const(p);
 701           const jbyte dirty = CardTableModRefBS::dirty_card_val();
 702 
 703           bool is_bad = !(from->is_young()
 704                           || to->rem_set()->contains_reference(p)
 705                           || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
 706                               (_containing_obj->is_objArray() ?
 707                                   cv_field == dirty
 708                                : cv_obj == dirty || cv_field == dirty));
 709           if (is_bad) {
 710             MutexLockerEx x(ParGCRareEvent_lock,
 711                             Mutex::_no_safepoint_check_flag);
 712 
 713             if (!_failures) {
 714               gclog_or_tty->cr();
 715               gclog_or_tty->print_cr("----------");
 716             }
 717             gclog_or_tty->print_cr("Missing rem set entry:");
 718             gclog_or_tty->print_cr("Field " PTR_FORMAT " "
 719                                    "of obj " PTR_FORMAT ", "
 720                                    "in region " HR_FORMAT,
 721                                    p2i(p), p2i(_containing_obj),
 722                                    HR_FORMAT_PARAMS(from));
 723             _containing_obj->print_on(gclog_or_tty);
 724             gclog_or_tty->print_cr("points to obj " PTR_FORMAT " "
 725                                    "in region " HR_FORMAT,
 726                                    p2i(obj),
 727                                    HR_FORMAT_PARAMS(to));
 728             obj->print_on(gclog_or_tty);
 729             gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",
 730                           cv_obj, cv_field);
 731             gclog_or_tty->print_cr("----------");
 732             gclog_or_tty->flush();
 733             _failures = true;
 734             if (!failed) _n_failures++;
 735           }
 736         }
 737       }
 738     }
 739   }
 740 };
 741 
 742 // This really ought to be commoned up into OffsetTableContigSpace somehow.
 743 // We would need a mechanism to make that code skip dead objects.
 744 
 745 void HeapRegion::verify(VerifyOption vo,
 746                         bool* failures) const {
 747   G1CollectedHeap* g1 = G1CollectedHeap::heap();
 748   *failures = false;
 749   HeapWord* p = bottom();
 750   HeapWord* prev_p = NULL;
 751   VerifyLiveClosure vl_cl(g1, vo);
 752   bool is_region_humongous = is_humongous();
 753   size_t object_num = 0;
 754   while (p < top()) {
 755     oop obj = oop(p);
 756     size_t obj_size = block_size(p);
 757     object_num += 1;
 758 
 759     if (is_region_humongous != g1->is_humongous(obj_size) &&
 760         !g1->is_obj_dead(obj, this)) { // Dead objects may have bigger block_size since they span several objects.
 761       gclog_or_tty->print_cr("obj " PTR_FORMAT " is of %shumongous size ("
 762                              SIZE_FORMAT " words) in a %shumongous region",
 763                              p2i(p), g1->is_humongous(obj_size) ? "" : "non-",
 764                              obj_size, is_region_humongous ? "" : "non-");
 765        *failures = true;
 766        return;
 767     }
 768 
 769     if (!g1->is_obj_dead_cond(obj, this, vo)) {
 770       if (obj->is_oop()) {
 771         Klass* klass = obj->klass();
 772         bool is_metaspace_object = Metaspace::contains(klass) ||
 773                                    (vo == VerifyOption_G1UsePrevMarking &&
 774                                    ClassLoaderDataGraph::unload_list_contains(klass));
 775         if (!is_metaspace_object) {
 776           gclog_or_tty->print_cr("klass " PTR_FORMAT " of object " PTR_FORMAT " "
 777                                  "not metadata", p2i(klass), p2i(obj));
 778           *failures = true;
 779           return;
 780         } else if (!klass->is_klass()) {
 781           gclog_or_tty->print_cr("klass " PTR_FORMAT " of object " PTR_FORMAT " "
 782                                  "not a klass", p2i(klass), p2i(obj));
 783           *failures = true;
 784           return;
 785         } else {
 786           vl_cl.set_containing_obj(obj);
 787           obj->oop_iterate_no_header(&vl_cl);
 788           if (vl_cl.failures()) {
 789             *failures = true;
 790           }
 791           if (G1MaxVerifyFailures >= 0 &&
 792               vl_cl.n_failures() >= G1MaxVerifyFailures) {
 793             return;
 794           }
 795         }
 796       } else {
 797         gclog_or_tty->print_cr(PTR_FORMAT " no an oop", p2i(obj));
 798         *failures = true;
 799         return;
 800       }
 801     }
 802     prev_p = p;
 803     p += obj_size;
 804   }
 805 
 806   if (!is_young() && !is_empty()) {
 807     _offsets.verify();
 808   }
 809 
 810   if (is_region_humongous) {
 811     oop obj = oop(this->humongous_start_region()->bottom());
 812     if ((HeapWord*)obj > bottom() || (HeapWord*)obj + obj->size() < bottom()) {
 813       gclog_or_tty->print_cr("this humongous region is not part of its' humongous object " PTR_FORMAT, p2i(obj));
 814     }
 815   }
 816 
 817   if (!is_region_humongous && p != top()) {
 818     gclog_or_tty->print_cr("end of last object " PTR_FORMAT " "
 819                            "does not match top " PTR_FORMAT, p2i(p), p2i(top()));
 820     *failures = true;
 821     return;
 822   }
 823 
 824   HeapWord* the_end = end();
 825   // Do some extra BOT consistency checking for addresses in the
 826   // range [top, end). BOT look-ups in this range should yield
 827   // top. No point in doing that if top == end (there's nothing there).
 828   if (p < the_end) {
 829     // Look up top
 830     HeapWord* addr_1 = p;
 831     HeapWord* b_start_1 = _offsets.block_start_const(addr_1);
 832     if (b_start_1 != p) {
 833       gclog_or_tty->print_cr("BOT look up for top: " PTR_FORMAT " "
 834                              " yielded " PTR_FORMAT ", expecting " PTR_FORMAT,
 835                              p2i(addr_1), p2i(b_start_1), p2i(p));
 836       *failures = true;
 837       return;
 838     }
 839 
 840     // Look up top + 1
 841     HeapWord* addr_2 = p + 1;
 842     if (addr_2 < the_end) {
 843       HeapWord* b_start_2 = _offsets.block_start_const(addr_2);
 844       if (b_start_2 != p) {
 845         gclog_or_tty->print_cr("BOT look up for top + 1: " PTR_FORMAT " "
 846                                " yielded " PTR_FORMAT ", expecting " PTR_FORMAT,
 847                                p2i(addr_2), p2i(b_start_2), p2i(p));
 848         *failures = true;
 849         return;
 850       }
 851     }
 852 
 853     // Look up an address between top and end
 854     size_t diff = pointer_delta(the_end, p) / 2;
 855     HeapWord* addr_3 = p + diff;
 856     if (addr_3 < the_end) {
 857       HeapWord* b_start_3 = _offsets.block_start_const(addr_3);
 858       if (b_start_3 != p) {
 859         gclog_or_tty->print_cr("BOT look up for top + diff: " PTR_FORMAT " "
 860                                " yielded " PTR_FORMAT ", expecting " PTR_FORMAT,
 861                                p2i(addr_3), p2i(b_start_3), p2i(p));
 862         *failures = true;
 863         return;
 864       }
 865     }
 866 
 867     // Look up end - 1
 868     HeapWord* addr_4 = the_end - 1;
 869     HeapWord* b_start_4 = _offsets.block_start_const(addr_4);
 870     if (b_start_4 != p) {
 871       gclog_or_tty->print_cr("BOT look up for end - 1: " PTR_FORMAT " "
 872                              " yielded " PTR_FORMAT ", expecting " PTR_FORMAT,
 873                              p2i(addr_4), p2i(b_start_4), p2i(p));
 874       *failures = true;
 875       return;
 876     }
 877   }
 878 
 879   if (is_region_humongous && object_num > 1) {
 880     gclog_or_tty->print_cr("region [" PTR_FORMAT "," PTR_FORMAT "] is humongous "
 881                            "but has " SIZE_FORMAT ", objects",
 882                            p2i(bottom()), p2i(end()), object_num);
 883     *failures = true;
 884     return;
 885   }
 886 
 887   verify_strong_code_roots(vo, failures);
 888 }
 889 
 890 void HeapRegion::verify() const {
 891   bool dummy = false;
 892   verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
 893 }
 894 
 895 void HeapRegion::prepare_for_compaction(CompactPoint* cp) {
 896   scan_and_forward(this, cp);
 897 }
 898 
 899 // G1OffsetTableContigSpace code; copied from space.cpp.  Hope this can go
 900 // away eventually.
 901 
 902 void G1OffsetTableContigSpace::clear(bool mangle_space) {
 903   set_top(bottom());
 904   _scan_top = bottom();
 905   CompactibleSpace::clear(mangle_space);
 906   reset_bot();
 907 }
 908 
 909 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
 910   Space::set_bottom(new_bottom);
 911   _offsets.set_bottom(new_bottom);
 912 }
 913 
 914 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {
 915   assert(new_end == _bottom + HeapRegion::GrainWords, "set_end should only ever be set to _bottom + HeapRegion::GrainWords");
 916   Space::set_end(new_end);
 917   _offsets.resize(new_end - bottom());
 918 }
 919 
 920 #ifndef PRODUCT
 921 void G1OffsetTableContigSpace::mangle_unused_area() {
 922   mangle_unused_area_complete();
 923 }
 924 
 925 void G1OffsetTableContigSpace::mangle_unused_area_complete() {
 926   SpaceMangler::mangle_region(MemRegion(top(), end()));
 927 }
 928 #endif
 929 
 930 void G1OffsetTableContigSpace::print() const {
 931   print_short();
 932   gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
 933                 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
 934                 p2i(bottom()), p2i(top()), p2i(_offsets.threshold()), p2i(end()));
 935 }
 936 
 937 HeapWord* G1OffsetTableContigSpace::initialize_threshold() {
 938   return _offsets.initialize_threshold();
 939 }
 940 
 941 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start,
 942                                                     HeapWord* end) {
 943   _offsets.alloc_block(start, end);
 944   return _offsets.threshold();
 945 }
 946 
 947 HeapWord* G1OffsetTableContigSpace::scan_top() const {
 948   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 949   HeapWord* local_top = top();
 950   OrderAccess::loadload();
 951   const unsigned local_time_stamp = _gc_time_stamp;
 952   assert(local_time_stamp <= g1h->get_gc_time_stamp(), "invariant");
 953   if (local_time_stamp < g1h->get_gc_time_stamp()) {
 954     return local_top;
 955   } else {
 956     return _scan_top;
 957   }
 958 }
 959 
 960 void G1OffsetTableContigSpace::record_timestamp() {
 961   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 962   unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();
 963 
 964   if (_gc_time_stamp < curr_gc_time_stamp) {
 965     // Setting the time stamp here tells concurrent readers to look at
 966     // scan_top to know the maximum allowed address to look at.
 967 
 968     // scan_top should be bottom for all regions except for the
 969     // retained old alloc region which should have scan_top == top
 970     HeapWord* st = _scan_top;
 971     guarantee(st == _bottom || st == _top, "invariant");
 972 
 973     _gc_time_stamp = curr_gc_time_stamp;
 974   }
 975 }
 976 
 977 void G1OffsetTableContigSpace::record_retained_region() {
 978   // scan_top is the maximum address where it's safe for the next gc to
 979   // scan this region.
 980   _scan_top = top();
 981 }
 982 
 983 void G1OffsetTableContigSpace::safe_object_iterate(ObjectClosure* blk) {
 984   object_iterate(blk);
 985 }
 986 
 987 void G1OffsetTableContigSpace::object_iterate(ObjectClosure* blk) {
 988   HeapWord* p = bottom();
 989   while (p < top()) {
 990     if (block_is_obj(p)) {
 991       blk->do_object(oop(p));
 992     }
 993     p += block_size(p);
 994   }
 995 }
 996 
 997 G1OffsetTableContigSpace::
 998 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
 999                          MemRegion mr) :
1000   _offsets(sharedOffsetArray, mr),
1001   _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
1002   _gc_time_stamp(0)
1003 {
1004   _offsets.set_space(this);
1005 }
1006 
1007 void G1OffsetTableContigSpace::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
1008   CompactibleSpace::initialize(mr, clear_space, mangle_space);
1009   _top = bottom();
1010   _scan_top = bottom();
1011   set_saved_mark_word(NULL);
1012   reset_bot();
1013 }
1014 
--- EOF ---