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 "logging/log.hpp"
  38 #include "memory/iterator.hpp"
  39 #include "oops/oop.inline.hpp"
  40 #include "runtime/atomic.inline.hpp"
  41 #include "runtime/orderAccess.inline.hpp"
  42 
  43 int    HeapRegion::LogOfHRGrainBytes = 0;
  44 int    HeapRegion::LogOfHRGrainWords = 0;
  45 size_t HeapRegion::GrainBytes        = 0;
  46 size_t HeapRegion::GrainWords        = 0;
  47 size_t HeapRegion::CardsPerRegion    = 0;
  48 
  49 HeapRegionDCTOC::HeapRegionDCTOC(G1CollectedHeap* g1,
  50                                  HeapRegion* hr,
  51                                  G1ParPushHeapRSClosure* cl,
  52                                  CardTableModRefBS::PrecisionStyle precision) :
  53   DirtyCardToOopClosure(hr, cl, precision, NULL),
  54   _hr(hr), _rs_scan(cl), _g1(g1) { }
  55 
  56 FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r,
  57                                                    OopClosure* oc) :
  58   _r_bottom(r->bottom()), _r_end(r->end()), _oc(oc) { }
  59 
  60 void HeapRegionDCTOC::walk_mem_region(MemRegion mr,
  61                                       HeapWord* bottom,
  62                                       HeapWord* top) {
  63   G1CollectedHeap* g1h = _g1;
  64   size_t oop_size;
  65   HeapWord* cur = bottom;
  66 
  67   // Start filtering what we add to the remembered set. If the object is
  68   // not considered dead, either because it is marked (in the mark bitmap)
  69   // or it was allocated after marking finished, then we add it. Otherwise
  70   // we can safely ignore the object.
  71   if (!g1h->is_obj_dead(oop(cur), _hr)) {
  72     oop_size = oop(cur)->oop_iterate_size(_rs_scan, mr);
  73   } else {
  74     oop_size = _hr->block_size(cur);
  75   }
  76 
  77   cur += oop_size;
  78 
  79   if (cur < top) {
  80     oop cur_oop = oop(cur);
  81     oop_size = _hr->block_size(cur);
  82     HeapWord* next_obj = cur + oop_size;
  83     while (next_obj < top) {
  84       // Keep filtering the remembered set.
  85       if (!g1h->is_obj_dead(cur_oop, _hr)) {
  86         // Bottom lies entirely below top, so we can call the
  87         // non-memRegion version of oop_iterate below.
  88         cur_oop->oop_iterate(_rs_scan);
  89       }
  90       cur = next_obj;
  91       cur_oop = oop(cur);
  92       oop_size = _hr->block_size(cur);
  93       next_obj = cur + oop_size;
  94     }
  95 
  96     // Last object. Need to do dead-obj filtering here too.
  97     if (!g1h->is_obj_dead(oop(cur), _hr)) {
  98       oop(cur)->oop_iterate(_rs_scan, mr);
  99     }
 100   }
 101 }
 102 
 103 size_t HeapRegion::max_region_size() {
 104   return HeapRegionBounds::max_size();
 105 }
 106 
 107 size_t HeapRegion::min_region_size_in_words() {
 108   return HeapRegionBounds::min_size() >> LogHeapWordSize;
 109 }
 110 
 111 void HeapRegion::setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size) {
 112   size_t region_size = G1HeapRegionSize;
 113   if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {
 114     size_t average_heap_size = (initial_heap_size + max_heap_size) / 2;
 115     region_size = MAX2(average_heap_size / HeapRegionBounds::target_number(),
 116                        HeapRegionBounds::min_size());
 117   }
 118 
 119   int region_size_log = log2_long((jlong) region_size);
 120   // Recalculate the region size to make sure it's a power of
 121   // 2. This means that region_size is the largest power of 2 that's
 122   // <= what we've calculated so far.
 123   region_size = ((size_t)1 << region_size_log);
 124 
 125   // Now make sure that we don't go over or under our limits.
 126   if (region_size < HeapRegionBounds::min_size()) {
 127     region_size = HeapRegionBounds::min_size();
 128   } else if (region_size > HeapRegionBounds::max_size()) {
 129     region_size = HeapRegionBounds::max_size();
 130   }
 131 
 132   // And recalculate the log.
 133   region_size_log = log2_long((jlong) region_size);
 134 
 135   // Now, set up the globals.
 136   guarantee(LogOfHRGrainBytes == 0, "we should only set it once");
 137   LogOfHRGrainBytes = region_size_log;
 138 
 139   guarantee(LogOfHRGrainWords == 0, "we should only set it once");
 140   LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize;
 141 
 142   guarantee(GrainBytes == 0, "we should only set it once");
 143   // The cast to int is safe, given that we've bounded region_size by
 144   // MIN_REGION_SIZE and MAX_REGION_SIZE.
 145   GrainBytes = region_size;
 146 
 147   guarantee(GrainWords == 0, "we should only set it once");
 148   GrainWords = GrainBytes >> LogHeapWordSize;
 149   guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity");
 150 
 151   guarantee(CardsPerRegion == 0, "we should only set it once");
 152   CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift;
 153 }
 154 
 155 void HeapRegion::reset_after_compaction() {
 156   G1OffsetTableContigSpace::reset_after_compaction();
 157   // After a compaction the mark bitmap is invalid, so we must
 158   // treat all objects as being inside the unmarked area.
 159   zero_marked_bytes();
 160   init_top_at_mark_start();
 161 }
 162 
 163 void HeapRegion::hr_clear(bool par, bool clear_space, bool locked) {
 164   assert(_humongous_start_region == NULL,
 165          "we should have already filtered out humongous regions");
 166   assert(_end == orig_end(),
 167          "we should have already filtered out humongous regions");
 168   assert(!in_collection_set(),
 169          "Should not clear heap region %u in the collection set", hrm_index());
 170 
 171   set_allocation_context(AllocationContext::system());
 172   set_young_index_in_cset(-1);
 173   uninstall_surv_rate_group();
 174   set_free();
 175   reset_pre_dummy_top();
 176 
 177   if (!par) {
 178     // If this is parallel, this will be done later.
 179     HeapRegionRemSet* hrrs = rem_set();
 180     if (locked) {
 181       hrrs->clear_locked();
 182     } else {
 183       hrrs->clear();
 184     }
 185   }
 186   zero_marked_bytes();
 187 
 188   _offsets.resize(HeapRegion::GrainWords);
 189   init_top_at_mark_start();
 190   if (clear_space) clear(SpaceDecorator::Mangle);
 191 }
 192 
 193 void HeapRegion::par_clear() {
 194   assert(used() == 0, "the region should have been already cleared");
 195   assert(capacity() == HeapRegion::GrainBytes, "should be back to normal");
 196   HeapRegionRemSet* hrrs = rem_set();
 197   hrrs->clear();
 198   CardTableModRefBS* ct_bs =
 199     barrier_set_cast<CardTableModRefBS>(G1CollectedHeap::heap()->barrier_set());
 200   ct_bs->clear(MemRegion(bottom(), end()));
 201 }
 202 
 203 void HeapRegion::calc_gc_efficiency() {
 204   // GC efficiency is the ratio of how much space would be
 205   // reclaimed over how long we predict it would take to reclaim it.
 206   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 207   G1CollectorPolicy* g1p = g1h->g1_policy();
 208 
 209   // Retrieve a prediction of the elapsed time for this region for
 210   // a mixed gc because the region will only be evacuated during a
 211   // mixed gc.
 212   double region_elapsed_time_ms =
 213     g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */);
 214   _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms;
 215 }
 216 
 217 void HeapRegion::set_starts_humongous(HeapWord* new_top, HeapWord* new_end) {
 218   assert(!is_humongous(), "sanity / pre-condition");
 219   assert(end() == orig_end(),
 220          "Should be normal before the humongous object allocation");
 221   assert(top() == bottom(), "should be empty");
 222   assert(bottom() <= new_top && new_top <= new_end, "pre-condition");
 223 
 224   _type.set_starts_humongous();
 225   _humongous_start_region = this;
 226 
 227   set_end(new_end);
 228   _offsets.set_for_starts_humongous(new_top);
 229 }
 230 
 231 void HeapRegion::set_continues_humongous(HeapRegion* first_hr) {
 232   assert(!is_humongous(), "sanity / pre-condition");
 233   assert(end() == orig_end(),
 234          "Should be normal before the humongous object allocation");
 235   assert(top() == bottom(), "should be empty");
 236   assert(first_hr->is_starts_humongous(), "pre-condition");
 237 
 238   _type.set_continues_humongous();
 239   _humongous_start_region = first_hr;
 240 }
 241 
 242 void HeapRegion::clear_humongous() {
 243   assert(is_humongous(), "pre-condition");
 244 
 245   if (is_starts_humongous()) {
 246     assert(top() <= end(), "pre-condition");
 247     set_end(orig_end());
 248     if (top() > end()) {
 249       // at least one "continues humongous" region after it
 250       set_top(end());
 251     }
 252   } else {
 253     // continues humongous
 254     assert(end() == orig_end(), "sanity");
 255   }
 256 
 257   assert(capacity() == HeapRegion::GrainBytes, "pre-condition");
 258   _humongous_start_region = NULL;
 259 }
 260 
 261 HeapRegion::HeapRegion(uint hrm_index,
 262                        G1BlockOffsetSharedArray* sharedOffsetArray,
 263                        MemRegion mr) :
 264     G1OffsetTableContigSpace(sharedOffsetArray, mr),
 265     _hrm_index(hrm_index),
 266     _allocation_context(AllocationContext::system()),
 267     _humongous_start_region(NULL),
 268     _next_in_special_set(NULL),
 269     _evacuation_failed(false),
 270     _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0),
 271     _next_young_region(NULL),
 272     _next_dirty_cards_region(NULL), _next(NULL), _prev(NULL),
 273 #ifdef ASSERT
 274     _containing_set(NULL),
 275 #endif // ASSERT
 276      _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),
 277     _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),
 278     _predicted_bytes_to_copy(0)
 279 {
 280   _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);
 281   assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
 282 
 283   initialize(mr);
 284 }
 285 
 286 void HeapRegion::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
 287   assert(_rem_set->is_empty(), "Remembered set must be empty");
 288 
 289   G1OffsetTableContigSpace::initialize(mr, clear_space, mangle_space);
 290 
 291   hr_clear(false /*par*/, false /*clear_space*/);
 292   set_top(bottom());
 293   record_timestamp();
 294 
 295   assert(mr.end() == orig_end(),
 296          "Given region end address " PTR_FORMAT " should match exactly "
 297          "bottom plus one region size, i.e. " PTR_FORMAT,
 298          p2i(mr.end()), p2i(orig_end()));
 299 }
 300 
 301 CompactibleSpace* HeapRegion::next_compaction_space() const {
 302   return G1CollectedHeap::heap()->next_compaction_region(this);
 303 }
 304 
 305 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,
 306                                                     bool during_conc_mark) {
 307   // We always recreate the prev marking info and we'll explicitly
 308   // mark all objects we find to be self-forwarded on the prev
 309   // bitmap. So all objects need to be below PTAMS.
 310   _prev_marked_bytes = 0;
 311 
 312   if (during_initial_mark) {
 313     // During initial-mark, we'll also explicitly mark all objects
 314     // we find to be self-forwarded on the next bitmap. So all
 315     // objects need to be below NTAMS.
 316     _next_top_at_mark_start = top();
 317     _next_marked_bytes = 0;
 318   } else if (during_conc_mark) {
 319     // During concurrent mark, all objects in the CSet (including
 320     // the ones we find to be self-forwarded) are implicitly live.
 321     // So all objects need to be above NTAMS.
 322     _next_top_at_mark_start = bottom();
 323     _next_marked_bytes = 0;
 324   }
 325 }
 326 
 327 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark,
 328                                                   bool during_conc_mark,
 329                                                   size_t marked_bytes) {
 330   assert(marked_bytes <= used(),
 331          "marked: " SIZE_FORMAT " used: " SIZE_FORMAT, marked_bytes, used());
 332   _prev_top_at_mark_start = top();
 333   _prev_marked_bytes = marked_bytes;
 334 }
 335 
 336 HeapWord*
 337 HeapRegion::object_iterate_mem_careful(MemRegion mr,
 338                                                  ObjectClosure* cl) {
 339   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 340   // We used to use "block_start_careful" here.  But we're actually happy
 341   // to update the BOT while we do this...
 342   HeapWord* cur = block_start(mr.start());
 343   mr = mr.intersection(used_region());
 344   if (mr.is_empty()) return NULL;
 345   // Otherwise, find the obj that extends onto mr.start().
 346 
 347   assert(cur <= mr.start()
 348          && (oop(cur)->klass_or_null() == NULL ||
 349              cur + oop(cur)->size() > mr.start()),
 350          "postcondition of block_start");
 351   oop obj;
 352   while (cur < mr.end()) {
 353     obj = oop(cur);
 354     if (obj->klass_or_null() == NULL) {
 355       // Ran into an unparseable point.
 356       return cur;
 357     } else if (!g1h->is_obj_dead(obj)) {
 358       cl->do_object(obj);
 359     }
 360     cur += block_size(cur);
 361   }
 362   return NULL;
 363 }
 364 
 365 HeapWord*
 366 HeapRegion::
 367 oops_on_card_seq_iterate_careful(MemRegion mr,
 368                                  FilterOutOfRegionClosure* cl,
 369                                  bool filter_young,
 370                                  jbyte* card_ptr) {
 371   // Currently, we should only have to clean the card if filter_young
 372   // is true and vice versa.
 373   if (filter_young) {
 374     assert(card_ptr != NULL, "pre-condition");
 375   } else {
 376     assert(card_ptr == NULL, "pre-condition");
 377   }
 378   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 379 
 380   // If we're within a stop-world GC, then we might look at a card in a
 381   // GC alloc region that extends onto a GC LAB, which may not be
 382   // parseable.  Stop such at the "scan_top" of the region.
 383   if (g1h->is_gc_active()) {
 384     mr = mr.intersection(MemRegion(bottom(), scan_top()));
 385   } else {
 386     mr = mr.intersection(used_region());
 387   }
 388   if (mr.is_empty()) return NULL;
 389   // Otherwise, find the obj that extends onto mr.start().
 390 
 391   // The intersection of the incoming mr (for the card) and the
 392   // allocated part of the region is non-empty. This implies that
 393   // we have actually allocated into this region. The code in
 394   // G1CollectedHeap.cpp that allocates a new region sets the
 395   // is_young tag on the region before allocating. Thus we
 396   // safely know if this region is young.
 397   if (is_young() && filter_young) {
 398     return NULL;
 399   }
 400 
 401   assert(!is_young(), "check value of filter_young");
 402 
 403   // We can only clean the card here, after we make the decision that
 404   // the card is not young. And we only clean the card if we have been
 405   // asked to (i.e., card_ptr != NULL).
 406   if (card_ptr != NULL) {
 407     *card_ptr = CardTableModRefBS::clean_card_val();
 408     // We must complete this write before we do any of the reads below.
 409     OrderAccess::storeload();
 410   }
 411 
 412   // Cache the boundaries of the memory region in some const locals
 413   HeapWord* const start = mr.start();
 414   HeapWord* const end = mr.end();
 415 
 416   // We used to use "block_start_careful" here.  But we're actually happy
 417   // to update the BOT while we do this...
 418   HeapWord* cur = block_start(start);
 419   assert(cur <= start, "Postcondition");
 420 
 421   oop obj;
 422 
 423   HeapWord* next = cur;
 424   do {
 425     cur = next;
 426     obj = oop(cur);
 427     if (obj->klass_or_null() == NULL) {
 428       // Ran into an unparseable point.
 429       return cur;
 430     }
 431     // Otherwise...
 432     next = cur + block_size(cur);
 433   } while (next <= start);
 434 
 435   // If we finish the above loop...We have a parseable object that
 436   // begins on or before the start of the memory region, and ends
 437   // inside or spans the entire region.
 438   assert(cur <= start, "Loop postcondition");
 439   assert(obj->klass_or_null() != NULL, "Loop postcondition");
 440 
 441   do {
 442     obj = oop(cur);
 443     assert((cur + block_size(cur)) > (HeapWord*)obj, "Loop invariant");
 444     if (obj->klass_or_null() == NULL) {
 445       // Ran into an unparseable point.
 446       return cur;
 447     }
 448 
 449     // Advance the current pointer. "obj" still points to the object to iterate.
 450     cur = cur + block_size(cur);
 451 
 452     if (!g1h->is_obj_dead(obj)) {
 453       // Non-objArrays are sometimes marked imprecise at the object start. We
 454       // always need to iterate over them in full.
 455       // We only iterate over object arrays in full if they are completely contained
 456       // in the memory region.
 457       if (!obj->is_objArray() || (((HeapWord*)obj) >= start && cur <= end)) {
 458         obj->oop_iterate(cl);
 459       } else {
 460         obj->oop_iterate(cl, mr);
 461       }
 462     }
 463   } while (cur < end);
 464 
 465   return NULL;
 466 }
 467 
 468 // Code roots support
 469 
 470 void HeapRegion::add_strong_code_root(nmethod* nm) {
 471   HeapRegionRemSet* hrrs = rem_set();
 472   hrrs->add_strong_code_root(nm);
 473 }
 474 
 475 void HeapRegion::add_strong_code_root_locked(nmethod* nm) {
 476   assert_locked_or_safepoint(CodeCache_lock);
 477   HeapRegionRemSet* hrrs = rem_set();
 478   hrrs->add_strong_code_root_locked(nm);
 479 }
 480 
 481 void HeapRegion::remove_strong_code_root(nmethod* nm) {
 482   HeapRegionRemSet* hrrs = rem_set();
 483   hrrs->remove_strong_code_root(nm);
 484 }
 485 
 486 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const {
 487   HeapRegionRemSet* hrrs = rem_set();
 488   hrrs->strong_code_roots_do(blk);
 489 }
 490 
 491 class VerifyStrongCodeRootOopClosure: public OopClosure {
 492   const HeapRegion* _hr;
 493   nmethod* _nm;
 494   bool _failures;
 495   bool _has_oops_in_region;
 496 
 497   template <class T> void do_oop_work(T* p) {
 498     T heap_oop = oopDesc::load_heap_oop(p);
 499     if (!oopDesc::is_null(heap_oop)) {
 500       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
 501 
 502       // Note: not all the oops embedded in the nmethod are in the
 503       // current region. We only look at those which are.
 504       if (_hr->is_in(obj)) {
 505         // Object is in the region. Check that its less than top
 506         if (_hr->top() <= (HeapWord*)obj) {
 507           // Object is above top
 508           log_info(gc, verify)("Object " PTR_FORMAT " in region [" PTR_FORMAT ", " PTR_FORMAT ") is above top " PTR_FORMAT,


 509                                p2i(obj), p2i(_hr->bottom()), p2i(_hr->end()), p2i(_hr->top()));
 510           _failures = true;
 511           return;
 512         }
 513         // Nmethod has at least one oop in the current region
 514         _has_oops_in_region = true;
 515       }
 516     }
 517   }
 518 
 519 public:
 520   VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm):
 521     _hr(hr), _failures(false), _has_oops_in_region(false) {}
 522 
 523   void do_oop(narrowOop* p) { do_oop_work(p); }
 524   void do_oop(oop* p)       { do_oop_work(p); }
 525 
 526   bool failures()           { return _failures; }
 527   bool has_oops_in_region() { return _has_oops_in_region; }
 528 };
 529 
 530 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
 531   const HeapRegion* _hr;
 532   bool _failures;
 533 public:
 534   VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) :
 535     _hr(hr), _failures(false) {}
 536 
 537   void do_code_blob(CodeBlob* cb) {
 538     nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
 539     if (nm != NULL) {
 540       // Verify that the nemthod is live
 541       if (!nm->is_alive()) {
 542         log_info(gc, verify)("region [" PTR_FORMAT "," PTR_FORMAT "] has dead nmethod " PTR_FORMAT " in its strong code roots",

 543                              p2i(_hr->bottom()), p2i(_hr->end()), p2i(nm));
 544         _failures = true;
 545       } else {
 546         VerifyStrongCodeRootOopClosure oop_cl(_hr, nm);
 547         nm->oops_do(&oop_cl);
 548         if (!oop_cl.has_oops_in_region()) {
 549           log_info(gc, verify)("region [" PTR_FORMAT "," PTR_FORMAT "] has nmethod " PTR_FORMAT " in its strong code roots with no pointers into region",


 550                                p2i(_hr->bottom()), p2i(_hr->end()), p2i(nm));
 551           _failures = true;
 552         } else if (oop_cl.failures()) {
 553           log_info(gc, verify)("region [" PTR_FORMAT "," PTR_FORMAT "] has other failures for nmethod " PTR_FORMAT,

 554                                p2i(_hr->bottom()), p2i(_hr->end()), p2i(nm));
 555           _failures = true;
 556         }
 557       }
 558     }
 559   }
 560 
 561   bool failures()       { return _failures; }
 562 };
 563 
 564 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const {
 565   if (!G1VerifyHeapRegionCodeRoots) {
 566     // We're not verifying code roots.
 567     return;
 568   }
 569   if (vo == VerifyOption_G1UseMarkWord) {
 570     // Marking verification during a full GC is performed after class
 571     // unloading, code cache unloading, etc so the strong code roots
 572     // attached to each heap region are in an inconsistent state. They won't
 573     // be consistent until the strong code roots are rebuilt after the
 574     // actual GC. Skip verifying the strong code roots in this particular
 575     // time.
 576     assert(VerifyDuringGC, "only way to get here");
 577     return;
 578   }
 579 
 580   HeapRegionRemSet* hrrs = rem_set();
 581   size_t strong_code_roots_length = hrrs->strong_code_roots_list_length();
 582 
 583   // if this region is empty then there should be no entries
 584   // on its strong code root list
 585   if (is_empty()) {
 586     if (strong_code_roots_length > 0) {
 587       log_info(gc, verify)("region [" PTR_FORMAT "," PTR_FORMAT "] is empty but has " SIZE_FORMAT " code root entries",

 588                            p2i(bottom()), p2i(end()), strong_code_roots_length);
 589       *failures = true;
 590     }
 591     return;
 592   }
 593 
 594   if (is_continues_humongous()) {
 595     if (strong_code_roots_length > 0) {
 596       log_info(gc, verify)("region " HR_FORMAT " is a continuation of a humongous region but has " SIZE_FORMAT " code root entries",

 597                            HR_FORMAT_PARAMS(this), strong_code_roots_length);
 598       *failures = true;
 599     }
 600     return;
 601   }
 602 
 603   VerifyStrongCodeRootCodeBlobClosure cb_cl(this);
 604   strong_code_roots_do(&cb_cl);
 605 
 606   if (cb_cl.failures()) {
 607     *failures = true;
 608   }
 609 }
 610 
 611 void HeapRegion::print() const { print_on(tty); }
 612 void HeapRegion::print_on(outputStream* st) const {
 613   st->print("AC%4u", allocation_context());
 614 
 615   st->print(" %2s", get_short_type_str());
 616   if (in_collection_set())
 617     st->print(" CS");
 618   else
 619     st->print("   ");
 620   st->print(" TS %5d", _gc_time_stamp);
 621   st->print(" PTAMS " PTR_FORMAT " NTAMS " PTR_FORMAT,
 622             p2i(prev_top_at_mark_start()), p2i(next_top_at_mark_start()));
 623   G1OffsetTableContigSpace::print_on(st);
 624 }
 625 
 626 class VerifyLiveClosure: public OopClosure {
 627 private:
 628   G1CollectedHeap* _g1h;
 629   CardTableModRefBS* _bs;
 630   oop _containing_obj;
 631   bool _failures;
 632   int _n_failures;
 633   VerifyOption _vo;
 634 public:
 635   // _vo == UsePrevMarking -> use "prev" marking information,
 636   // _vo == UseNextMarking -> use "next" marking information,
 637   // _vo == UseMarkWord    -> use mark word from object header.
 638   VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) :
 639     _g1h(g1h), _bs(barrier_set_cast<CardTableModRefBS>(g1h->barrier_set())),
 640     _containing_obj(NULL), _failures(false), _n_failures(0), _vo(vo)
 641   { }
 642 
 643   void set_containing_obj(oop obj) {
 644     _containing_obj = obj;
 645   }
 646 
 647   bool failures() { return _failures; }
 648   int n_failures() { return _n_failures; }
 649 
 650   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
 651   virtual void do_oop(      oop* p) { do_oop_work(p); }
 652 
 653   void print_object(outputStream* out, oop obj) {
 654 #ifdef PRODUCT
 655     Klass* k = obj->klass();
 656     const char* class_name = k->external_name();
 657     out->print_cr("class name %s", class_name);
 658 #else // PRODUCT
 659     obj->print_on(out);
 660 #endif // PRODUCT
 661   }
 662 
 663   template <class T>
 664   void do_oop_work(T* p) {
 665     assert(_containing_obj != NULL, "Precondition");
 666     assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
 667            "Precondition");
 668     T heap_oop = oopDesc::load_heap_oop(p);
 669     LogHandle(gc, verify) log;
 670     if (!oopDesc::is_null(heap_oop)) {
 671       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
 672       bool failed = false;
 673       if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) {
 674         MutexLockerEx x(ParGCRareEvent_lock,
 675                         Mutex::_no_safepoint_check_flag);
 676 
 677         if (!_failures) {
 678           log.info("----------");

 679         }
 680         ResourceMark rm;
 681         if (!_g1h->is_in_closed_subset(obj)) {
 682           HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
 683           log.info("Field " PTR_FORMAT " of live obj " PTR_FORMAT " in region [" PTR_FORMAT ", " PTR_FORMAT ")",
 684                    p2i(p), p2i(_containing_obj), p2i(from->bottom()), p2i(from->end()));
 685           print_object(log.info_stream(), _containing_obj);
 686           log.info("points to obj " PTR_FORMAT " not in the heap", p2i(obj));




 687         } else {
 688           HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
 689           HeapRegion* to   = _g1h->heap_region_containing((HeapWord*)obj);
 690           log.info("Field " PTR_FORMAT " of live obj " PTR_FORMAT " in region [" PTR_FORMAT ", " PTR_FORMAT ")",
 691                    p2i(p), p2i(_containing_obj), p2i(from->bottom()), p2i(from->end()));
 692           print_object(log.info_stream(), _containing_obj);
 693           log.info("points to dead obj " PTR_FORMAT " in region [" PTR_FORMAT ", " PTR_FORMAT ")",




 694                    p2i(obj), p2i(to->bottom()), p2i(to->end()));
 695           print_object(log.info_stream(), obj);
 696         }
 697         log.info("----------");

 698         _failures = true;
 699         failed = true;
 700         _n_failures++;
 701       }
 702 
 703       if (!_g1h->collector_state()->full_collection() || G1VerifyRSetsDuringFullGC) {
 704         HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
 705         HeapRegion* to   = _g1h->heap_region_containing(obj);
 706         if (from != NULL && to != NULL &&
 707             from != to &&
 708             !to->is_pinned()) {
 709           jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
 710           jbyte cv_field = *_bs->byte_for_const(p);
 711           const jbyte dirty = CardTableModRefBS::dirty_card_val();
 712 
 713           bool is_bad = !(from->is_young()
 714                           || to->rem_set()->contains_reference(p)
 715                           || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
 716                               (_containing_obj->is_objArray() ?
 717                                   cv_field == dirty
 718                                : cv_obj == dirty || cv_field == dirty));
 719           if (is_bad) {
 720             MutexLockerEx x(ParGCRareEvent_lock,
 721                             Mutex::_no_safepoint_check_flag);
 722 
 723             if (!_failures) {
 724               log.info("----------");

 725             }
 726             log.info("Missing rem set entry:");
 727             log.info("Field " PTR_FORMAT " of obj " PTR_FORMAT ", in region " HR_FORMAT,
 728                      p2i(p), p2i(_containing_obj), HR_FORMAT_PARAMS(from));
 729             ResourceMark rm;
 730             _containing_obj->print_on(log.info_stream());
 731             log.info("points to obj " PTR_FORMAT " in region " HR_FORMAT, p2i(obj), HR_FORMAT_PARAMS(to));
 732             obj->print_on(log.info_stream());
 733             log.info("Obj head CTE = %d, field CTE = %d.", cv_obj, cv_field);
 734             log.info("----------");







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