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_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, _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 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(_end == orig_end(),
 166          "we should have already filtered out humongous regions");
 167   assert(!in_collection_set(),
 168          "Should not clear heap region %u in the collection set", hrm_index());
 169 
 170   set_allocation_context(AllocationContext::system());
 171   set_young_index_in_cset(-1);
 172   uninstall_surv_rate_group();
 173   set_free();
 174   reset_pre_dummy_top();
 175 
 176   if (!par) {
 177     // If this is parallel, this will be done later.
 178     HeapRegionRemSet* hrrs = rem_set();
 179     if (locked) {
 180       hrrs->clear_locked();
 181     } else {
 182       hrrs->clear();
 183     }
 184   }
 185   zero_marked_bytes();
 186 
 187   _offsets.resize(HeapRegion::GrainWords);
 188   init_top_at_mark_start();
 189   if (clear_space) clear(SpaceDecorator::Mangle);
 190 }
 191 
 192 void HeapRegion::par_clear() {
 193   assert(used() == 0, "the region should have been already cleared");
 194   assert(capacity() == HeapRegion::GrainBytes, "should be back to normal");
 195   HeapRegionRemSet* hrrs = rem_set();
 196   hrrs->clear();
 197   CardTableModRefBS* ct_bs =
 198     barrier_set_cast<CardTableModRefBS>(G1CollectedHeap::heap()->barrier_set());
 199   ct_bs->clear(MemRegion(bottom(), end()));
 200 }
 201 
 202 void HeapRegion::calc_gc_efficiency() {
 203   // GC efficiency is the ratio of how much space would be
 204   // reclaimed over how long we predict it would take to reclaim it.
 205   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 206   G1CollectorPolicy* g1p = g1h->g1_policy();
 207 
 208   // Retrieve a prediction of the elapsed time for this region for
 209   // a mixed gc because the region will only be evacuated during a
 210   // mixed gc.
 211   double region_elapsed_time_ms =
 212     g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */);
 213   _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms;
 214 }
 215 
 216 void HeapRegion::set_starts_humongous(HeapWord* new_top, HeapWord* new_end) {
 217   assert(!is_humongous(), "sanity / pre-condition");
 218   assert(end() == orig_end(),
 219          "Should be normal before the humongous object allocation");
 220   assert(top() == bottom(), "should be empty");
 221   assert(bottom() <= new_top && new_top <= new_end, "pre-condition");
 222 
 223   _type.set_starts_humongous();
 224   _humongous_start_region = this;
 225 
 226   set_end(new_end);
 227   _offsets.set_for_starts_humongous(new_top);
 228 }
 229 
 230 void HeapRegion::set_continues_humongous(HeapRegion* first_hr) {
 231   assert(!is_humongous(), "sanity / pre-condition");
 232   assert(end() == orig_end(),
 233          "Should be normal before the humongous object allocation");
 234   assert(top() == bottom(), "should be empty");
 235   assert(first_hr->is_starts_humongous(), "pre-condition");
 236 
 237   _type.set_continues_humongous();
 238   _humongous_start_region = first_hr;
 239 }
 240 
 241 void HeapRegion::clear_humongous() {
 242   assert(is_humongous(), "pre-condition");
 243 
 244   if (is_starts_humongous()) {
 245     assert(top() <= end(), "pre-condition");
 246     set_end(orig_end());
 247     if (top() > end()) {
 248       // at least one "continues humongous" region after it
 249       set_top(end());
 250     }
 251   } else {
 252     // continues humongous
 253     assert(end() == orig_end(), "sanity");
 254   }
 255 
 256   assert(capacity() == HeapRegion::GrainBytes, "pre-condition");
 257   _humongous_start_region = NULL;
 258 }
 259 
 260 HeapRegion::HeapRegion(uint hrm_index,
 261                        G1BlockOffsetSharedArray* sharedOffsetArray,
 262                        MemRegion mr) :
 263     G1OffsetTableContigSpace(sharedOffsetArray, mr),
 264     _hrm_index(hrm_index),
 265     _allocation_context(AllocationContext::system()),
 266     _humongous_start_region(NULL),
 267     _next_in_special_set(NULL),
 268     _evacuation_failed(false),
 269     _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0),
 270     _next_young_region(NULL),
 271     _next_dirty_cards_region(NULL), _next(NULL), _prev(NULL),
 272 #ifdef ASSERT
 273     _containing_set(NULL),
 274 #endif // ASSERT
 275      _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),
 276     _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),
 277     _predicted_bytes_to_copy(0)
 278 {
 279   _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);
 280   assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
 281 
 282   initialize(mr);
 283 }
 284 
 285 void HeapRegion::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
 286   assert(_rem_set->is_empty(), "Remembered set must be empty");
 287 
 288   G1OffsetTableContigSpace::initialize(mr, clear_space, mangle_space);
 289 
 290   hr_clear(false /*par*/, false /*clear_space*/);
 291   set_top(bottom());
 292   record_timestamp();
 293 
 294   assert(mr.end() == orig_end(),
 295          "Given region end address " PTR_FORMAT " should match exactly "
 296          "bottom plus one region size, i.e. " PTR_FORMAT,
 297          p2i(mr.end()), p2i(orig_end()));
 298 }
 299 
 300 CompactibleSpace* HeapRegion::next_compaction_space() const {
 301   return G1CollectedHeap::heap()->next_compaction_region(this);
 302 }
 303 
 304 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,
 305                                                     bool during_conc_mark) {
 306   // We always recreate the prev marking info and we'll explicitly
 307   // mark all objects we find to be self-forwarded on the prev
 308   // bitmap. So all objects need to be below PTAMS.
 309   _prev_marked_bytes = 0;
 310 
 311   if (during_initial_mark) {
 312     // During initial-mark, we'll also explicitly mark all objects
 313     // we find to be self-forwarded on the next bitmap. So all
 314     // objects need to be below NTAMS.
 315     _next_top_at_mark_start = top();
 316     _next_marked_bytes = 0;
 317   } else if (during_conc_mark) {
 318     // During concurrent mark, all objects in the CSet (including
 319     // the ones we find to be self-forwarded) are implicitly live.
 320     // So all objects need to be above NTAMS.
 321     _next_top_at_mark_start = bottom();
 322     _next_marked_bytes = 0;
 323   }
 324 }
 325 
 326 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark,
 327                                                   bool during_conc_mark,
 328                                                   size_t marked_bytes) {
 329   assert(marked_bytes <= used(),
 330          "marked: " SIZE_FORMAT " used: " SIZE_FORMAT, marked_bytes, used());
 331   _prev_top_at_mark_start = top();
 332   _prev_marked_bytes = marked_bytes;
 333 }
 334 
 335 HeapWord*
 336 HeapRegion::object_iterate_mem_careful(MemRegion mr,
 337                                                  ObjectClosure* cl) {
 338   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 339   // We used to use "block_start_careful" here.  But we're actually happy
 340   // to update the BOT while we do this...
 341   HeapWord* cur = block_start(mr.start());
 342   mr = mr.intersection(used_region());
 343   if (mr.is_empty()) return NULL;
 344   // Otherwise, find the obj that extends onto mr.start().
 345 
 346   assert(cur <= mr.start()
 347          && (oop(cur)->klass_or_null() == NULL ||
 348              cur + oop(cur)->size() > mr.start()),
 349          "postcondition of block_start");
 350   oop obj;
 351   while (cur < mr.end()) {
 352     obj = oop(cur);
 353     if (obj->klass_or_null() == NULL) {
 354       // Ran into an unparseable point.
 355       return cur;
 356     } else if (!g1h->is_obj_dead(obj)) {
 357       cl->do_object(obj);
 358     }
 359     cur += block_size(cur);
 360   }
 361   return NULL;
 362 }
 363 
 364 HeapWord*
 365 HeapRegion::
 366 oops_on_card_seq_iterate_careful(MemRegion mr,
 367                                  FilterOutOfRegionClosure* cl,
 368                                  bool filter_young,
 369                                  jbyte* card_ptr) {
 370   // Currently, we should only have to clean the card if filter_young
 371   // is true and vice versa.
 372   if (filter_young) {
 373     assert(card_ptr != NULL, "pre-condition");
 374   } else {
 375     assert(card_ptr == NULL, "pre-condition");
 376   }
 377   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 378 
 379   // If we're within a stop-world GC, then we might look at a card in a
 380   // GC alloc region that extends onto a GC LAB, which may not be
 381   // parseable.  Stop such at the "scan_top" of the region.
 382   if (g1h->is_gc_active()) {
 383     mr = mr.intersection(MemRegion(bottom(), scan_top()));
 384   } else {
 385     mr = mr.intersection(used_region());
 386   }
 387   if (mr.is_empty()) return NULL;
 388   // Otherwise, find the obj that extends onto mr.start().
 389 
 390   // The intersection of the incoming mr (for the card) and the
 391   // allocated part of the region is non-empty. This implies that
 392   // we have actually allocated into this region. The code in
 393   // G1CollectedHeap.cpp that allocates a new region sets the
 394   // is_young tag on the region before allocating. Thus we
 395   // safely know if this region is young.
 396   if (is_young() && filter_young) {
 397     return NULL;
 398   }
 399 
 400   assert(!is_young(), "check value of filter_young");
 401 
 402   // We can only clean the card here, after we make the decision that
 403   // the card is not young. And we only clean the card if we have been
 404   // asked to (i.e., card_ptr != NULL).
 405   if (card_ptr != NULL) {
 406     *card_ptr = CardTableModRefBS::clean_card_val();
 407     // We must complete this write before we do any of the reads below.
 408     OrderAccess::storeload();
 409   }
 410 
 411   // Cache the boundaries of the memory region in some const locals
 412   HeapWord* const start = mr.start();
 413   HeapWord* const end = mr.end();
 414 
 415   // We used to use "block_start_careful" here.  But we're actually happy
 416   // to update the BOT while we do this...
 417   HeapWord* cur = block_start(start);
 418   assert(cur <= start, "Postcondition");
 419 
 420   oop obj;
 421 
 422   HeapWord* next = cur;
 423   do {
 424     cur = next;
 425     obj = oop(cur);
 426     if (obj->klass_or_null() == NULL) {
 427       // Ran into an unparseable point.
 428       return cur;
 429     }
 430     // Otherwise...
 431     next = cur + block_size(cur);
 432   } while (next <= start);
 433 
 434   // If we finish the above loop...We have a parseable object that
 435   // begins on or before the start of the memory region, and ends
 436   // inside or spans the entire region.
 437   assert(cur <= start, "Loop postcondition");
 438   assert(obj->klass_or_null() != NULL, "Loop postcondition");
 439 
 440   do {
 441     obj = oop(cur);
 442     assert((cur + block_size(cur)) > (HeapWord*)obj, "Loop invariant");
 443     if (obj->klass_or_null() == NULL) {
 444       // Ran into an unparseable point.
 445       return cur;
 446     }
 447 
 448     // Advance the current pointer. "obj" still points to the object to iterate.
 449     cur = cur + block_size(cur);
 450 
 451     if (!g1h->is_obj_dead(obj)) {
 452       // Non-objArrays are sometimes marked imprecise at the object start. We
 453       // always need to iterate over them in full.
 454       // We only iterate over object arrays in full if they are completely contained
 455       // in the memory region.
 456       if (!obj->is_objArray() || (((HeapWord*)obj) >= start && cur <= end)) {
 457         obj->oop_iterate(cl);
 458       } else {
 459         obj->oop_iterate(cl, mr);
 460       }
 461     }
 462   } while (cur < end);
 463 
 464   return NULL;
 465 }
 466 
 467 // Code roots support
 468 
 469 void HeapRegion::add_strong_code_root(nmethod* nm) {
 470   HeapRegionRemSet* hrrs = rem_set();
 471   hrrs->add_strong_code_root(nm);
 472 }
 473 
 474 void HeapRegion::add_strong_code_root_locked(nmethod* nm) {
 475   assert_locked_or_safepoint(CodeCache_lock);
 476   HeapRegionRemSet* hrrs = rem_set();
 477   hrrs->add_strong_code_root_locked(nm);
 478 }
 479 
 480 void HeapRegion::remove_strong_code_root(nmethod* nm) {
 481   HeapRegionRemSet* hrrs = rem_set();
 482   hrrs->remove_strong_code_root(nm);
 483 }
 484 
 485 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const {
 486   HeapRegionRemSet* hrrs = rem_set();
 487   hrrs->strong_code_roots_do(blk);
 488 }
 489 
 490 class VerifyStrongCodeRootOopClosure: public OopClosure {
 491   const HeapRegion* _hr;
 492   nmethod* _nm;
 493   bool _failures;
 494   bool _has_oops_in_region;
 495 
 496   template <class T> void do_oop_work(T* p) {
 497     T heap_oop = oopDesc::load_heap_oop(p);
 498     if (!oopDesc::is_null(heap_oop)) {
 499       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
 500 
 501       // Note: not all the oops embedded in the nmethod are in the
 502       // current region. We only look at those which are.
 503       if (_hr->is_in(obj)) {
 504         // Object is in the region. Check that its less than top
 505         if (_hr->top() <= (HeapWord*)obj) {
 506           // Object is above top
 507           gclog_or_tty->print_cr("Object " PTR_FORMAT " in region "
 508                                  "[" PTR_FORMAT ", " PTR_FORMAT ") is above "
 509                                  "top " PTR_FORMAT,
 510                                  p2i(obj), p2i(_hr->bottom()), p2i(_hr->end()), p2i(_hr->top()));
 511           _failures = true;
 512           return;
 513         }
 514         // Nmethod has at least one oop in the current region
 515         _has_oops_in_region = true;
 516       }
 517     }
 518   }
 519 
 520 public:
 521   VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm):
 522     _hr(hr), _failures(false), _has_oops_in_region(false) {}
 523 
 524   void do_oop(narrowOop* p) { do_oop_work(p); }
 525   void do_oop(oop* p)       { do_oop_work(p); }
 526 
 527   bool failures()           { return _failures; }
 528   bool has_oops_in_region() { return _has_oops_in_region; }
 529 };
 530 
 531 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
 532   const HeapRegion* _hr;
 533   bool _failures;
 534 public:
 535   VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) :
 536     _hr(hr), _failures(false) {}
 537 
 538   void do_code_blob(CodeBlob* cb) {
 539     nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
 540     if (nm != NULL) {
 541       // Verify that the nemthod is live
 542       if (!nm->is_alive()) {
 543         gclog_or_tty->print_cr("region [" PTR_FORMAT "," PTR_FORMAT "] has dead nmethod "
 544                                PTR_FORMAT " in its strong code roots",
 545                                p2i(_hr->bottom()), p2i(_hr->end()), p2i(nm));
 546         _failures = true;
 547       } else {
 548         VerifyStrongCodeRootOopClosure oop_cl(_hr, nm);
 549         nm->oops_do(&oop_cl);
 550         if (!oop_cl.has_oops_in_region()) {
 551           gclog_or_tty->print_cr("region [" PTR_FORMAT "," PTR_FORMAT "] has nmethod "
 552                                  PTR_FORMAT " in its strong code roots "
 553                                  "with no pointers into region",
 554                                  p2i(_hr->bottom()), p2i(_hr->end()), p2i(nm));
 555           _failures = true;
 556         } else if (oop_cl.failures()) {
 557           gclog_or_tty->print_cr("region [" PTR_FORMAT "," PTR_FORMAT "] has other "
 558                                  "failures for nmethod " PTR_FORMAT,
 559                                  p2i(_hr->bottom()), p2i(_hr->end()), p2i(nm));
 560           _failures = true;
 561         }
 562       }
 563     }
 564   }
 565 
 566   bool failures()       { return _failures; }
 567 };
 568 
 569 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const {
 570   if (!G1VerifyHeapRegionCodeRoots) {
 571     // We're not verifying code roots.
 572     return;
 573   }
 574   if (vo == VerifyOption_G1UseMarkWord) {
 575     // Marking verification during a full GC is performed after class
 576     // unloading, code cache unloading, etc so the strong code roots
 577     // attached to each heap region are in an inconsistent state. They won't
 578     // be consistent until the strong code roots are rebuilt after the
 579     // actual GC. Skip verifying the strong code roots in this particular
 580     // time.
 581     assert(VerifyDuringGC, "only way to get here");
 582     return;
 583   }
 584 
 585   HeapRegionRemSet* hrrs = rem_set();
 586   size_t strong_code_roots_length = hrrs->strong_code_roots_list_length();
 587 
 588   // if this region is empty then there should be no entries
 589   // on its strong code root list
 590   if (is_empty()) {
 591     if (strong_code_roots_length > 0) {
 592       gclog_or_tty->print_cr("region [" PTR_FORMAT "," PTR_FORMAT "] is empty "
 593                              "but has " SIZE_FORMAT " code root entries",
 594                              p2i(bottom()), p2i(end()), strong_code_roots_length);
 595       *failures = true;
 596     }
 597     return;
 598   }
 599 
 600   if (is_continues_humongous()) {
 601     if (strong_code_roots_length > 0) {
 602       gclog_or_tty->print_cr("region " HR_FORMAT " is a continuation of a humongous "
 603                              "region but has " SIZE_FORMAT " code root entries",
 604                              HR_FORMAT_PARAMS(this), strong_code_roots_length);
 605       *failures = true;
 606     }
 607     return;
 608   }
 609 
 610   VerifyStrongCodeRootCodeBlobClosure cb_cl(this);
 611   strong_code_roots_do(&cb_cl);
 612 
 613   if (cb_cl.failures()) {
 614     *failures = true;
 615   }
 616 }
 617 
 618 void HeapRegion::print() const { print_on(gclog_or_tty); }
 619 void HeapRegion::print_on(outputStream* st) const {
 620   st->print("AC%4u", allocation_context());
 621 
 622   st->print(" %2s", get_short_type_str());
 623   if (in_collection_set())
 624     st->print(" CS");
 625   else
 626     st->print("   ");
 627   st->print(" TS %5d", _gc_time_stamp);
 628   st->print(" PTAMS " PTR_FORMAT " NTAMS " PTR_FORMAT,
 629             p2i(prev_top_at_mark_start()), p2i(next_top_at_mark_start()));
 630   G1OffsetTableContigSpace::print_on(st);
 631 }
 632 
 633 class VerifyLiveClosure: public OopClosure {
 634 private:
 635   G1CollectedHeap* _g1h;
 636   CardTableModRefBS* _bs;
 637   oop _containing_obj;
 638   bool _failures;
 639   int _n_failures;
 640   VerifyOption _vo;
 641 public:
 642   // _vo == UsePrevMarking -> use "prev" marking information,
 643   // _vo == UseNextMarking -> use "next" marking information,
 644   // _vo == UseMarkWord    -> use mark word from object header.
 645   VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) :
 646     _g1h(g1h), _bs(barrier_set_cast<CardTableModRefBS>(g1h->barrier_set())),
 647     _containing_obj(NULL), _failures(false), _n_failures(0), _vo(vo)
 648   { }
 649 
 650   void set_containing_obj(oop obj) {
 651     _containing_obj = obj;
 652   }
 653 
 654   bool failures() { return _failures; }
 655   int n_failures() { return _n_failures; }
 656 
 657   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
 658   virtual void do_oop(      oop* p) { do_oop_work(p); }
 659 
 660   void print_object(outputStream* out, oop obj) {
 661 #ifdef PRODUCT
 662     Klass* k = obj->klass();
 663     const char* class_name = k->external_name();
 664     out->print_cr("class name %s", class_name);
 665 #else // PRODUCT
 666     obj->print_on(out);
 667 #endif // PRODUCT
 668   }
 669 
 670   template <class T>
 671   void do_oop_work(T* p) {
 672     assert(_containing_obj != NULL, "Precondition");
 673     assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
 674            "Precondition");
 675     T heap_oop = oopDesc::load_heap_oop(p);

 676     if (!oopDesc::is_null(heap_oop)) {
 677       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
 678       bool failed = false;
 679       if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) {
 680         MutexLockerEx x(ParGCRareEvent_lock,
 681                         Mutex::_no_safepoint_check_flag);
 682 
 683         if (!_failures) {
 684           gclog_or_tty->cr();
 685           gclog_or_tty->print_cr("----------");
 686         }

 687         if (!_g1h->is_in_closed_subset(obj)) {
 688           HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
 689           gclog_or_tty->print_cr("Field " PTR_FORMAT
 690                                  " of live obj " PTR_FORMAT " in region "
 691                                  "[" PTR_FORMAT ", " PTR_FORMAT ")",
 692                                  p2i(p), p2i(_containing_obj),
 693                                  p2i(from->bottom()), p2i(from->end()));
 694           print_object(gclog_or_tty, _containing_obj);
 695           gclog_or_tty->print_cr("points to obj " PTR_FORMAT " not in the heap",
 696                                  p2i(obj));
 697         } else {
 698           HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
 699           HeapRegion* to   = _g1h->heap_region_containing((HeapWord*)obj);
 700           gclog_or_tty->print_cr("Field " PTR_FORMAT
 701                                  " of live obj " PTR_FORMAT " in region "
 702                                  "[" PTR_FORMAT ", " PTR_FORMAT ")",
 703                                  p2i(p), p2i(_containing_obj),
 704                                  p2i(from->bottom()), p2i(from->end()));
 705           print_object(gclog_or_tty, _containing_obj);
 706           gclog_or_tty->print_cr("points to dead obj " PTR_FORMAT " in region "
 707                                  "[" PTR_FORMAT ", " PTR_FORMAT ")",
 708                                  p2i(obj), p2i(to->bottom()), p2i(to->end()));
 709           print_object(gclog_or_tty, obj);
 710         }
 711         gclog_or_tty->print_cr("----------");
 712         gclog_or_tty->flush();
 713         _failures = true;
 714         failed = true;
 715         _n_failures++;
 716       }
 717 
 718       if (!_g1h->collector_state()->full_collection() || G1VerifyRSetsDuringFullGC) {
 719         HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
 720         HeapRegion* to   = _g1h->heap_region_containing(obj);
 721         if (from != NULL && to != NULL &&
 722             from != to &&
 723             !to->is_pinned()) {
 724           jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
 725           jbyte cv_field = *_bs->byte_for_const(p);
 726           const jbyte dirty = CardTableModRefBS::dirty_card_val();
 727 
 728           bool is_bad = !(from->is_young()
 729                           || to->rem_set()->contains_reference(p)
 730                           || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
 731                               (_containing_obj->is_objArray() ?
 732                                   cv_field == dirty
 733                                : cv_obj == dirty || cv_field == dirty));
 734           if (is_bad) {
 735             MutexLockerEx x(ParGCRareEvent_lock,
 736                             Mutex::_no_safepoint_check_flag);
 737 
 738             if (!_failures) {
 739               gclog_or_tty->cr();
 740               gclog_or_tty->print_cr("----------");
 741             }
 742             gclog_or_tty->print_cr("Missing rem set entry:");
 743             gclog_or_tty->print_cr("Field " PTR_FORMAT " "
 744                                    "of obj " PTR_FORMAT ", "
 745                                    "in region " HR_FORMAT,
 746                                    p2i(p), p2i(_containing_obj),
 747                                    HR_FORMAT_PARAMS(from));
 748             _containing_obj->print_on(gclog_or_tty);
 749             gclog_or_tty->print_cr("points to obj " PTR_FORMAT " "
 750                                    "in region " HR_FORMAT,
 751                                    p2i(obj),
 752                                    HR_FORMAT_PARAMS(to));
 753             obj->print_on(gclog_or_tty);
 754             gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",
 755                           cv_obj, cv_field);
 756             gclog_or_tty->print_cr("----------");
 757             gclog_or_tty->flush();
 758             _failures = true;
 759             if (!failed) _n_failures++;
 760           }
 761         }
 762       }
 763     }
 764   }
 765 };
 766 
 767 // This really ought to be commoned up into OffsetTableContigSpace somehow.
 768 // We would need a mechanism to make that code skip dead objects.
 769 
 770 void HeapRegion::verify(VerifyOption vo,
 771                         bool* failures) const {
 772   G1CollectedHeap* g1 = G1CollectedHeap::heap();
 773   *failures = false;
 774   HeapWord* p = bottom();
 775   HeapWord* prev_p = NULL;
 776   VerifyLiveClosure vl_cl(g1, vo);
 777   bool is_region_humongous = is_humongous();
 778   size_t object_num = 0;
 779   while (p < top()) {
 780     oop obj = oop(p);
 781     size_t obj_size = block_size(p);
 782     object_num += 1;
 783 
 784     if (is_region_humongous != g1->is_humongous(obj_size) &&
 785         !g1->is_obj_dead(obj, this)) { // Dead objects may have bigger block_size since they span several objects.
 786       gclog_or_tty->print_cr("obj " PTR_FORMAT " is of %shumongous size ("
 787                              SIZE_FORMAT " words) in a %shumongous region",
 788                              p2i(p), g1->is_humongous(obj_size) ? "" : "non-",
 789                              obj_size, is_region_humongous ? "" : "non-");
 790        *failures = true;
 791        return;
 792     }
 793 
 794     if (!g1->is_obj_dead_cond(obj, this, vo)) {
 795       if (obj->is_oop()) {
 796         Klass* klass = obj->klass();
 797         bool is_metaspace_object = Metaspace::contains(klass) ||
 798                                    (vo == VerifyOption_G1UsePrevMarking &&
 799                                    ClassLoaderDataGraph::unload_list_contains(klass));
 800         if (!is_metaspace_object) {
 801           gclog_or_tty->print_cr("klass " PTR_FORMAT " of object " PTR_FORMAT " "
 802                                  "not metadata", p2i(klass), p2i(obj));
 803           *failures = true;
 804           return;
 805         } else if (!klass->is_klass()) {
 806           gclog_or_tty->print_cr("klass " PTR_FORMAT " of object " PTR_FORMAT " "
 807                                  "not a klass", p2i(klass), p2i(obj));
 808           *failures = true;
 809           return;
 810         } else {
 811           vl_cl.set_containing_obj(obj);
 812           obj->oop_iterate_no_header(&vl_cl);
 813           if (vl_cl.failures()) {
 814             *failures = true;
 815           }
 816           if (G1MaxVerifyFailures >= 0 &&
 817               vl_cl.n_failures() >= G1MaxVerifyFailures) {
 818             return;
 819           }
 820         }
 821       } else {
 822         gclog_or_tty->print_cr(PTR_FORMAT " no an oop", p2i(obj));
 823         *failures = true;
 824         return;
 825       }
 826     }
 827     prev_p = p;
 828     p += obj_size;
 829   }
 830 
 831   if (!is_young() && !is_empty()) {
 832     _offsets.verify();
 833   }
 834 
 835   if (p != top()) {
 836     gclog_or_tty->print_cr("end of last object " PTR_FORMAT " "
 837                            "does not match top " PTR_FORMAT, p2i(p), p2i(top()));
 838     *failures = true;
 839     return;
 840   }
 841 
 842   HeapWord* the_end = end();
 843   assert(p == top(), "it should still hold");
 844   // Do some extra BOT consistency checking for addresses in the
 845   // range [top, end). BOT look-ups in this range should yield
 846   // top. No point in doing that if top == end (there's nothing there).
 847   if (p < the_end) {
 848     // Look up top
 849     HeapWord* addr_1 = p;
 850     HeapWord* b_start_1 = _offsets.block_start_const(addr_1);
 851     if (b_start_1 != p) {
 852       gclog_or_tty->print_cr("BOT look up for top: " PTR_FORMAT " "
 853                              " yielded " PTR_FORMAT ", expecting " PTR_FORMAT,
 854                              p2i(addr_1), p2i(b_start_1), p2i(p));
 855       *failures = true;
 856       return;
 857     }
 858 
 859     // Look up top + 1
 860     HeapWord* addr_2 = p + 1;
 861     if (addr_2 < the_end) {
 862       HeapWord* b_start_2 = _offsets.block_start_const(addr_2);
 863       if (b_start_2 != p) {
 864         gclog_or_tty->print_cr("BOT look up for top + 1: " PTR_FORMAT " "
 865                                " yielded " PTR_FORMAT ", expecting " PTR_FORMAT,
 866                                p2i(addr_2), p2i(b_start_2), p2i(p));
 867         *failures = true;
 868         return;
 869       }
 870     }
 871 
 872     // Look up an address between top and end
 873     size_t diff = pointer_delta(the_end, p) / 2;
 874     HeapWord* addr_3 = p + diff;
 875     if (addr_3 < the_end) {
 876       HeapWord* b_start_3 = _offsets.block_start_const(addr_3);
 877       if (b_start_3 != p) {
 878         gclog_or_tty->print_cr("BOT look up for top + diff: " PTR_FORMAT " "
 879                                " yielded " PTR_FORMAT ", expecting " PTR_FORMAT,
 880                                p2i(addr_3), p2i(b_start_3), p2i(p));
 881         *failures = true;
 882         return;
 883       }
 884     }
 885 
 886     // Look up end - 1
 887     HeapWord* addr_4 = the_end - 1;
 888     HeapWord* b_start_4 = _offsets.block_start_const(addr_4);
 889     if (b_start_4 != p) {
 890       gclog_or_tty->print_cr("BOT look up for end - 1: " PTR_FORMAT " "
 891                              " yielded " PTR_FORMAT ", expecting " PTR_FORMAT,
 892                              p2i(addr_4), p2i(b_start_4), p2i(p));
 893       *failures = true;
 894       return;
 895     }
 896   }
 897 
 898   if (is_region_humongous && object_num > 1) {
 899     gclog_or_tty->print_cr("region [" PTR_FORMAT "," PTR_FORMAT "] is humongous "
 900                            "but has " SIZE_FORMAT ", objects",
 901                            p2i(bottom()), p2i(end()), object_num);
 902     *failures = true;
 903     return;
 904   }
 905 
 906   verify_strong_code_roots(vo, failures);
 907 }
 908 
 909 void HeapRegion::verify() const {
 910   bool dummy = false;
 911   verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
 912 }
 913 
 914 void HeapRegion::prepare_for_compaction(CompactPoint* cp) {
 915   scan_and_forward(this, cp);
 916 }
 917 
 918 // G1OffsetTableContigSpace code; copied from space.cpp.  Hope this can go
 919 // away eventually.
 920 
 921 void G1OffsetTableContigSpace::clear(bool mangle_space) {
 922   set_top(bottom());
 923   _scan_top = bottom();
 924   CompactibleSpace::clear(mangle_space);
 925   reset_bot();
 926 }
 927 
 928 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
 929   Space::set_bottom(new_bottom);
 930   _offsets.set_bottom(new_bottom);
 931 }
 932 
 933 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {
 934   Space::set_end(new_end);
 935   _offsets.resize(new_end - bottom());
 936 }
 937 
 938 #ifndef PRODUCT
 939 void G1OffsetTableContigSpace::mangle_unused_area() {
 940   mangle_unused_area_complete();
 941 }
 942 
 943 void G1OffsetTableContigSpace::mangle_unused_area_complete() {
 944   SpaceMangler::mangle_region(MemRegion(top(), end()));
 945 }
 946 #endif
 947 
 948 void G1OffsetTableContigSpace::print() const {
 949   print_short();
 950   gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
 951                 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
 952                 p2i(bottom()), p2i(top()), p2i(_offsets.threshold()), p2i(end()));
 953 }
 954 
 955 HeapWord* G1OffsetTableContigSpace::initialize_threshold() {
 956   return _offsets.initialize_threshold();
 957 }
 958 
 959 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start,
 960                                                     HeapWord* end) {
 961   _offsets.alloc_block(start, end);
 962   return _offsets.threshold();
 963 }
 964 
 965 HeapWord* G1OffsetTableContigSpace::scan_top() const {
 966   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 967   HeapWord* local_top = top();
 968   OrderAccess::loadload();
 969   const unsigned local_time_stamp = _gc_time_stamp;
 970   assert(local_time_stamp <= g1h->get_gc_time_stamp(), "invariant");
 971   if (local_time_stamp < g1h->get_gc_time_stamp()) {
 972     return local_top;
 973   } else {
 974     return _scan_top;
 975   }
 976 }
 977 
 978 void G1OffsetTableContigSpace::record_timestamp() {
 979   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 980   unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();
 981 
 982   if (_gc_time_stamp < curr_gc_time_stamp) {
 983     // Setting the time stamp here tells concurrent readers to look at
 984     // scan_top to know the maximum allowed address to look at.
 985 
 986     // scan_top should be bottom for all regions except for the
 987     // retained old alloc region which should have scan_top == top
 988     HeapWord* st = _scan_top;
 989     guarantee(st == _bottom || st == _top, "invariant");
 990 
 991     _gc_time_stamp = curr_gc_time_stamp;
 992   }
 993 }
 994 
 995 void G1OffsetTableContigSpace::record_retained_region() {
 996   // scan_top is the maximum address where it's safe for the next gc to
 997   // scan this region.
 998   _scan_top = top();
 999 }
1000 
1001 void G1OffsetTableContigSpace::safe_object_iterate(ObjectClosure* blk) {
1002   object_iterate(blk);
1003 }
1004 
1005 void G1OffsetTableContigSpace::object_iterate(ObjectClosure* blk) {
1006   HeapWord* p = bottom();
1007   while (p < top()) {
1008     if (block_is_obj(p)) {
1009       blk->do_object(oop(p));
1010     }
1011     p += block_size(p);
1012   }
1013 }
1014 
1015 G1OffsetTableContigSpace::
1016 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
1017                          MemRegion mr) :
1018   _offsets(sharedOffsetArray, mr),
1019   _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
1020   _gc_time_stamp(0)
1021 {
1022   _offsets.set_space(this);
1023 }
1024 
1025 void G1OffsetTableContigSpace::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
1026   CompactibleSpace::initialize(mr, clear_space, mangle_space);
1027   _top = bottom();
1028   _scan_top = bottom();
1029   set_saved_mark_word(NULL);
1030   reset_bot();
1031 }
1032 
--- EOF ---