1 /*
   2  * Copyright (c) 2001, 2016, 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/g1HeapRegionTraceType.hpp"
  30 #include "gc/g1/g1OopClosures.inline.hpp"
  31 #include "gc/g1/heapRegion.inline.hpp"
  32 #include "gc/g1/heapRegionBounds.inline.hpp"
  33 #include "gc/g1/heapRegionManager.inline.hpp"
  34 #include "gc/g1/heapRegionRemSet.hpp"
  35 #include "gc/g1/heapRegionTracer.hpp"
  36 #include "gc/shared/genOopClosures.inline.hpp"
  37 #include "gc/shared/space.inline.hpp"
  38 #include "logging/log.hpp"
  39 #include "memory/iterator.hpp"
  40 #include "memory/resourceArea.hpp"
  41 #include "oops/oop.inline.hpp"
  42 #include "runtime/atomic.inline.hpp"
  43 #include "runtime/orderAccess.inline.hpp"
  44 
  45 int    HeapRegion::LogOfHRGrainBytes = 0;
  46 int    HeapRegion::LogOfHRGrainWords = 0;
  47 size_t HeapRegion::GrainBytes        = 0;
  48 size_t HeapRegion::GrainWords        = 0;
  49 size_t HeapRegion::CardsPerRegion    = 0;
  50 
  51 HeapRegionDCTOC::HeapRegionDCTOC(G1CollectedHeap* g1,
  52                                  HeapRegion* hr,
  53                                  G1ParPushHeapRSClosure* cl,
  54                                  CardTableModRefBS::PrecisionStyle precision) :
  55   DirtyCardToOopClosure(hr, cl, precision, NULL),
  56   _hr(hr), _rs_scan(cl), _g1(g1) { }
  57 
  58 FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r,
  59                                                    OopClosure* oc) :
  60   _r_bottom(r->bottom()), _r_end(r->end()), _oc(oc) { }
  61 
  62 void HeapRegionDCTOC::walk_mem_region(MemRegion mr,
  63                                       HeapWord* bottom,
  64                                       HeapWord* top) {
  65   G1CollectedHeap* g1h = _g1;
  66   size_t oop_size;
  67   HeapWord* cur = bottom;
  68 
  69   // Start filtering what we add to the remembered set. If the object is
  70   // not considered dead, either because it is marked (in the mark bitmap)
  71   // or it was allocated after marking finished, then we add it. Otherwise
  72   // we can safely ignore the object.
  73   if (!g1h->is_obj_dead(oop(cur))) {
  74     oop_size = oop(cur)->oop_iterate_size(_rs_scan, mr);
  75   } else {
  76     oop_size = _hr->block_size(cur);
  77   }
  78 
  79   cur += oop_size;
  80 
  81   if (cur < top) {
  82     oop cur_oop = oop(cur);
  83     oop_size = _hr->block_size(cur);
  84     HeapWord* next_obj = cur + oop_size;
  85     while (next_obj < top) {
  86       // Keep filtering the remembered set.
  87       if (!g1h->is_obj_dead(cur_oop)) {
  88         // Bottom lies entirely below top, so we can call the
  89         // non-memRegion version of oop_iterate below.
  90         cur_oop->oop_iterate(_rs_scan);
  91       }
  92       cur = next_obj;
  93       cur_oop = oop(cur);
  94       oop_size = _hr->block_size(cur);
  95       next_obj = cur + oop_size;
  96     }
  97 
  98     // Last object. Need to do dead-obj filtering here too.
  99     if (!g1h->is_obj_dead(oop(cur))) {
 100       oop(cur)->oop_iterate(_rs_scan, mr);
 101     }
 102   }
 103 }
 104 
 105 size_t HeapRegion::max_region_size() {
 106   return HeapRegionBounds::max_size();
 107 }
 108 
 109 size_t HeapRegion::min_region_size_in_words() {
 110   return HeapRegionBounds::min_size() >> LogHeapWordSize;
 111 }
 112 
 113 void HeapRegion::setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size) {
 114   size_t region_size = G1HeapRegionSize;
 115   if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {
 116     size_t average_heap_size = (initial_heap_size + max_heap_size) / 2;
 117     region_size = MAX2(average_heap_size / HeapRegionBounds::target_number(),
 118                        HeapRegionBounds::min_size());
 119   }
 120 
 121   int region_size_log = log2_long((jlong) region_size);
 122   // Recalculate the region size to make sure it's a power of
 123   // 2. This means that region_size is the largest power of 2 that's
 124   // <= what we've calculated so far.
 125   region_size = ((size_t)1 << region_size_log);
 126 
 127   // Now make sure that we don't go over or under our limits.
 128   if (region_size < HeapRegionBounds::min_size()) {
 129     region_size = HeapRegionBounds::min_size();
 130   } else if (region_size > HeapRegionBounds::max_size()) {
 131     region_size = HeapRegionBounds::max_size();
 132   }
 133 
 134   // And recalculate the log.
 135   region_size_log = log2_long((jlong) region_size);
 136 
 137   // Now, set up the globals.
 138   guarantee(LogOfHRGrainBytes == 0, "we should only set it once");
 139   LogOfHRGrainBytes = region_size_log;
 140 
 141   guarantee(LogOfHRGrainWords == 0, "we should only set it once");
 142   LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize;
 143 
 144   guarantee(GrainBytes == 0, "we should only set it once");
 145   // The cast to int is safe, given that we've bounded region_size by
 146   // MIN_REGION_SIZE and MAX_REGION_SIZE.
 147   GrainBytes = region_size;
 148   log_info(gc, heap)("Heap region size: " SIZE_FORMAT "M", GrainBytes / M);
 149 
 150   guarantee(GrainWords == 0, "we should only set it once");
 151   GrainWords = GrainBytes >> LogHeapWordSize;
 152   guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity");
 153 
 154   guarantee(CardsPerRegion == 0, "we should only set it once");
 155   CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift;
 156 
 157   if (G1HeapRegionSize != GrainBytes) {
 158     FLAG_SET_ERGO(size_t, G1HeapRegionSize, GrainBytes);
 159   }
 160 }
 161 
 162 void HeapRegion::reset_after_compaction() {
 163   G1ContiguousSpace::reset_after_compaction();
 164   // After a compaction the mark bitmap is invalid, so we must
 165   // treat all objects as being inside the unmarked area.
 166   zero_marked_bytes();
 167   init_top_at_mark_start();
 168 }
 169 
 170 void HeapRegion::hr_clear(bool par, bool clear_space, bool locked) {
 171   assert(_humongous_start_region == NULL,
 172          "we should have already filtered out humongous regions");
 173   assert(!in_collection_set(),
 174          "Should not clear heap region %u in the collection set", hrm_index());
 175 
 176   set_allocation_context(AllocationContext::system());
 177   set_young_index_in_cset(-1);
 178   uninstall_surv_rate_group();
 179   set_free();
 180   reset_pre_dummy_top();
 181 
 182   if (!par) {
 183     // If this is parallel, this will be done later.
 184     HeapRegionRemSet* hrrs = rem_set();
 185     if (locked) {
 186       hrrs->clear_locked();
 187     } else {
 188       hrrs->clear();
 189     }
 190   }
 191   zero_marked_bytes();
 192 
 193   init_top_at_mark_start();
 194   _gc_time_stamp = G1CollectedHeap::heap()->get_gc_time_stamp();
 195   if (clear_space) clear(SpaceDecorator::Mangle);
 196 }
 197 
 198 void HeapRegion::par_clear() {
 199   assert(used() == 0, "the region should have been already cleared");
 200   assert(capacity() == HeapRegion::GrainBytes, "should be back to normal");
 201   HeapRegionRemSet* hrrs = rem_set();
 202   hrrs->clear();
 203   CardTableModRefBS* ct_bs =
 204     barrier_set_cast<CardTableModRefBS>(G1CollectedHeap::heap()->barrier_set());
 205   ct_bs->clear(MemRegion(bottom(), end()));
 206 }
 207 
 208 void HeapRegion::calc_gc_efficiency() {
 209   // GC efficiency is the ratio of how much space would be
 210   // reclaimed over how long we predict it would take to reclaim it.
 211   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 212   G1Policy* g1p = g1h->g1_policy();
 213 
 214   // Retrieve a prediction of the elapsed time for this region for
 215   // a mixed gc because the region will only be evacuated during a
 216   // mixed gc.
 217   double region_elapsed_time_ms =
 218     g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */);
 219   _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms;
 220 }
 221 
 222 void HeapRegion::set_free() {
 223   report_region_type_change(G1HeapRegionTraceType::Free);
 224   _type.set_free();
 225 }
 226 
 227 void HeapRegion::set_eden() {
 228   report_region_type_change(G1HeapRegionTraceType::Eden);
 229   _type.set_eden();
 230 }
 231 
 232 void HeapRegion::set_eden_pre_gc() {
 233   report_region_type_change(G1HeapRegionTraceType::Eden);
 234   _type.set_eden_pre_gc();
 235 }
 236 
 237 void HeapRegion::set_survivor() {
 238   report_region_type_change(G1HeapRegionTraceType::Survivor);
 239   _type.set_survivor();
 240 }
 241 
 242 void HeapRegion::set_old() {
 243   report_region_type_change(G1HeapRegionTraceType::Old);
 244   _type.set_old();
 245 }
 246 
 247 void HeapRegion::set_archive() {
 248   report_region_type_change(G1HeapRegionTraceType::Archive);
 249   _type.set_archive();
 250 }
 251 
 252 void HeapRegion::set_starts_humongous(HeapWord* obj_top, size_t fill_size) {
 253   assert(!is_humongous(), "sanity / pre-condition");
 254   assert(top() == bottom(), "should be empty");
 255 
 256   report_region_type_change(G1HeapRegionTraceType::StartsHumongous);
 257   _type.set_starts_humongous();
 258   _humongous_start_region = this;
 259 
 260   _bot_part.set_for_starts_humongous(obj_top, fill_size);
 261 }
 262 
 263 void HeapRegion::set_continues_humongous(HeapRegion* first_hr) {
 264   assert(!is_humongous(), "sanity / pre-condition");
 265   assert(top() == bottom(), "should be empty");
 266   assert(first_hr->is_starts_humongous(), "pre-condition");
 267 
 268   report_region_type_change(G1HeapRegionTraceType::ContinuesHumongous);
 269   _type.set_continues_humongous();
 270   _humongous_start_region = first_hr;
 271 }
 272 
 273 void HeapRegion::clear_humongous() {
 274   assert(is_humongous(), "pre-condition");
 275 
 276   assert(capacity() == HeapRegion::GrainBytes, "pre-condition");
 277   _humongous_start_region = NULL;
 278 }
 279 
 280 HeapRegion::HeapRegion(uint hrm_index,
 281                        G1BlockOffsetTable* bot,
 282                        MemRegion mr) :
 283     G1ContiguousSpace(bot),
 284     _hrm_index(hrm_index),
 285     _allocation_context(AllocationContext::system()),
 286     _humongous_start_region(NULL),
 287     _next_in_special_set(NULL),
 288     _evacuation_failed(false),
 289     _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0),
 290     _next(NULL), _prev(NULL),
 291 #ifdef ASSERT
 292     _containing_set(NULL),
 293 #endif // ASSERT
 294      _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),
 295     _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),
 296     _predicted_bytes_to_copy(0)
 297 {
 298   _rem_set = new HeapRegionRemSet(bot, this);
 299 
 300   initialize(mr);
 301 }
 302 
 303 void HeapRegion::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
 304   assert(_rem_set->is_empty(), "Remembered set must be empty");
 305 
 306   G1ContiguousSpace::initialize(mr, clear_space, mangle_space);
 307 
 308   hr_clear(false /*par*/, false /*clear_space*/);
 309   set_top(bottom());
 310   record_timestamp();
 311 }
 312 
 313 void HeapRegion::report_region_type_change(G1HeapRegionTraceType::Type to) {
 314   HeapRegionTracer::send_region_type_change(_hrm_index,
 315                                             get_trace_type(),
 316                                             to,
 317                                             (uintptr_t)bottom(),
 318                                             used(),
 319                                             (uint)allocation_context());
 320 }
 321 
 322 CompactibleSpace* HeapRegion::next_compaction_space() const {
 323   return G1CollectedHeap::heap()->next_compaction_region(this);
 324 }
 325 
 326 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,
 327                                                     bool during_conc_mark) {
 328   // We always recreate the prev marking info and we'll explicitly
 329   // mark all objects we find to be self-forwarded on the prev
 330   // bitmap. So all objects need to be below PTAMS.
 331   _prev_marked_bytes = 0;
 332 
 333   if (during_initial_mark) {
 334     // During initial-mark, we'll also explicitly mark all objects
 335     // we find to be self-forwarded on the next bitmap. So all
 336     // objects need to be below NTAMS.
 337     _next_top_at_mark_start = top();
 338     _next_marked_bytes = 0;
 339   } else if (during_conc_mark) {
 340     // During concurrent mark, all objects in the CSet (including
 341     // the ones we find to be self-forwarded) are implicitly live.
 342     // So all objects need to be above NTAMS.
 343     _next_top_at_mark_start = bottom();
 344     _next_marked_bytes = 0;
 345   }
 346 }
 347 
 348 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark,
 349                                                   bool during_conc_mark,
 350                                                   size_t marked_bytes) {
 351   assert(marked_bytes <= used(),
 352          "marked: " SIZE_FORMAT " used: " SIZE_FORMAT, marked_bytes, used());
 353   _prev_top_at_mark_start = top();
 354   _prev_marked_bytes = marked_bytes;
 355 }
 356 
 357 HeapWord*
 358 HeapRegion::object_iterate_mem_careful(MemRegion mr,
 359                                                  ObjectClosure* cl) {
 360   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 361   // We used to use "block_start_careful" here.  But we're actually happy
 362   // to update the BOT while we do this...
 363   HeapWord* cur = block_start(mr.start());
 364   mr = mr.intersection(used_region());
 365   if (mr.is_empty()) return NULL;
 366   // Otherwise, find the obj that extends onto mr.start().
 367 
 368   assert(cur <= mr.start()
 369          && (oop(cur)->klass_or_null() == NULL ||
 370              cur + oop(cur)->size() > mr.start()),
 371          "postcondition of block_start");
 372   oop obj;
 373   while (cur < mr.end()) {
 374     obj = oop(cur);
 375     if (obj->klass_or_null() == NULL) {
 376       // Ran into an unparseable point.
 377       return cur;
 378     } else if (!g1h->is_obj_dead(obj)) {
 379       cl->do_object(obj);
 380     }
 381     cur += block_size(cur);
 382   }
 383   return NULL;
 384 }
 385 
 386 HeapWord*
 387 HeapRegion::
 388 oops_on_card_seq_iterate_careful(MemRegion mr,
 389                                  FilterOutOfRegionClosure* cl,
 390                                  bool filter_young,
 391                                  jbyte* card_ptr) {
 392   // Currently, we should only have to clean the card if filter_young
 393   // is true and vice versa.
 394   if (filter_young) {
 395     assert(card_ptr != NULL, "pre-condition");
 396   } else {
 397     assert(card_ptr == NULL, "pre-condition");
 398   }
 399   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 400 
 401   // If we're within a stop-world GC, then we might look at a card in a
 402   // GC alloc region that extends onto a GC LAB, which may not be
 403   // parseable.  Stop such at the "scan_top" of the region.
 404   if (g1h->is_gc_active()) {
 405     mr = mr.intersection(MemRegion(bottom(), scan_top()));
 406   } else {
 407     mr = mr.intersection(used_region());
 408   }
 409   if (mr.is_empty()) return NULL;
 410   // Otherwise, find the obj that extends onto mr.start().
 411 
 412   // The intersection of the incoming mr (for the card) and the
 413   // allocated part of the region is non-empty. This implies that
 414   // we have actually allocated into this region. The code in
 415   // G1CollectedHeap.cpp that allocates a new region sets the
 416   // is_young tag on the region before allocating. Thus we
 417   // safely know if this region is young.
 418   if (is_young() && filter_young) {
 419     return NULL;
 420   }
 421 
 422   assert(!is_young(), "check value of filter_young");
 423 
 424   // We can only clean the card here, after we make the decision that
 425   // the card is not young. And we only clean the card if we have been
 426   // asked to (i.e., card_ptr != NULL).
 427   if (card_ptr != NULL) {
 428     *card_ptr = CardTableModRefBS::clean_card_val();
 429     // We must complete this write before we do any of the reads below.
 430     OrderAccess::storeload();
 431   }
 432 
 433   // Cache the boundaries of the memory region in some const locals
 434   HeapWord* const start = mr.start();
 435   HeapWord* const end = mr.end();
 436 
 437   // We used to use "block_start_careful" here.  But we're actually happy
 438   // to update the BOT while we do this...
 439   HeapWord* cur = block_start(start);
 440   assert(cur <= start, "Postcondition");
 441 
 442   oop obj;
 443 
 444   HeapWord* next = cur;
 445   do {
 446     cur = next;
 447     obj = oop(cur);
 448     if (obj->klass_or_null() == NULL) {
 449       // Ran into an unparseable point.
 450       return cur;
 451     }
 452     // Otherwise...
 453     next = cur + block_size(cur);
 454   } while (next <= start);
 455 
 456   // If we finish the above loop...We have a parseable object that
 457   // begins on or before the start of the memory region, and ends
 458   // inside or spans the entire region.
 459   assert(cur <= start, "Loop postcondition");
 460   assert(obj->klass_or_null() != NULL, "Loop postcondition");
 461 
 462   do {
 463     obj = oop(cur);
 464     assert((cur + block_size(cur)) > (HeapWord*)obj, "Loop invariant");
 465     if (obj->klass_or_null() == NULL) {
 466       // Ran into an unparseable point.
 467       return cur;
 468     }
 469 
 470     // Advance the current pointer. "obj" still points to the object to iterate.
 471     cur = cur + block_size(cur);
 472 
 473     if (!g1h->is_obj_dead(obj)) {
 474       // Non-objArrays are sometimes marked imprecise at the object start. We
 475       // always need to iterate over them in full.
 476       // We only iterate over object arrays in full if they are completely contained
 477       // in the memory region.
 478       if (!obj->is_objArray() || (((HeapWord*)obj) >= start && cur <= end)) {
 479         obj->oop_iterate(cl);
 480       } else {
 481         obj->oop_iterate(cl, mr);
 482       }
 483     }
 484   } while (cur < end);
 485 
 486   return NULL;
 487 }
 488 
 489 // Code roots support
 490 
 491 void HeapRegion::add_strong_code_root(nmethod* nm) {
 492   HeapRegionRemSet* hrrs = rem_set();
 493   hrrs->add_strong_code_root(nm);
 494 }
 495 
 496 void HeapRegion::add_strong_code_root_locked(nmethod* nm) {
 497   assert_locked_or_safepoint(CodeCache_lock);
 498   HeapRegionRemSet* hrrs = rem_set();
 499   hrrs->add_strong_code_root_locked(nm);
 500 }
 501 
 502 void HeapRegion::remove_strong_code_root(nmethod* nm) {
 503   HeapRegionRemSet* hrrs = rem_set();
 504   hrrs->remove_strong_code_root(nm);
 505 }
 506 
 507 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const {
 508   HeapRegionRemSet* hrrs = rem_set();
 509   hrrs->strong_code_roots_do(blk);
 510 }
 511 
 512 class VerifyStrongCodeRootOopClosure: public OopClosure {
 513   const HeapRegion* _hr;
 514   nmethod* _nm;
 515   bool _failures;
 516   bool _has_oops_in_region;
 517 
 518   template <class T> void do_oop_work(T* p) {
 519     T heap_oop = oopDesc::load_heap_oop(p);
 520     if (!oopDesc::is_null(heap_oop)) {
 521       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
 522 
 523       // Note: not all the oops embedded in the nmethod are in the
 524       // current region. We only look at those which are.
 525       if (_hr->is_in(obj)) {
 526         // Object is in the region. Check that its less than top
 527         if (_hr->top() <= (HeapWord*)obj) {
 528           // Object is above top
 529           log_error(gc, verify)("Object " PTR_FORMAT " in region [" PTR_FORMAT ", " PTR_FORMAT ") is above top " PTR_FORMAT,
 530                                p2i(obj), p2i(_hr->bottom()), p2i(_hr->end()), p2i(_hr->top()));
 531           _failures = true;
 532           return;
 533         }
 534         // Nmethod has at least one oop in the current region
 535         _has_oops_in_region = true;
 536       }
 537     }
 538   }
 539 
 540 public:
 541   VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm):
 542     _hr(hr), _failures(false), _has_oops_in_region(false) {}
 543 
 544   void do_oop(narrowOop* p) { do_oop_work(p); }
 545   void do_oop(oop* p)       { do_oop_work(p); }
 546 
 547   bool failures()           { return _failures; }
 548   bool has_oops_in_region() { return _has_oops_in_region; }
 549 };
 550 
 551 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
 552   const HeapRegion* _hr;
 553   bool _failures;
 554 public:
 555   VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) :
 556     _hr(hr), _failures(false) {}
 557 
 558   void do_code_blob(CodeBlob* cb) {
 559     nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
 560     if (nm != NULL) {
 561       // Verify that the nemthod is live
 562       if (!nm->is_alive()) {
 563         log_error(gc, verify)("region [" PTR_FORMAT "," PTR_FORMAT "] has dead nmethod " PTR_FORMAT " in its strong code roots",
 564                               p2i(_hr->bottom()), p2i(_hr->end()), p2i(nm));
 565         _failures = true;
 566       } else {
 567         VerifyStrongCodeRootOopClosure oop_cl(_hr, nm);
 568         nm->oops_do(&oop_cl);
 569         if (!oop_cl.has_oops_in_region()) {
 570           log_error(gc, verify)("region [" PTR_FORMAT "," PTR_FORMAT "] has nmethod " PTR_FORMAT " in its strong code roots with no pointers into region",
 571                                 p2i(_hr->bottom()), p2i(_hr->end()), p2i(nm));
 572           _failures = true;
 573         } else if (oop_cl.failures()) {
 574           log_error(gc, verify)("region [" PTR_FORMAT "," PTR_FORMAT "] has other failures for nmethod " PTR_FORMAT,
 575                                 p2i(_hr->bottom()), p2i(_hr->end()), p2i(nm));
 576           _failures = true;
 577         }
 578       }
 579     }
 580   }
 581 
 582   bool failures()       { return _failures; }
 583 };
 584 
 585 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const {
 586   if (!G1VerifyHeapRegionCodeRoots) {
 587     // We're not verifying code roots.
 588     return;
 589   }
 590   if (vo == VerifyOption_G1UseMarkWord) {
 591     // Marking verification during a full GC is performed after class
 592     // unloading, code cache unloading, etc so the strong code roots
 593     // attached to each heap region are in an inconsistent state. They won't
 594     // be consistent until the strong code roots are rebuilt after the
 595     // actual GC. Skip verifying the strong code roots in this particular
 596     // time.
 597     assert(VerifyDuringGC, "only way to get here");
 598     return;
 599   }
 600 
 601   HeapRegionRemSet* hrrs = rem_set();
 602   size_t strong_code_roots_length = hrrs->strong_code_roots_list_length();
 603 
 604   // if this region is empty then there should be no entries
 605   // on its strong code root list
 606   if (is_empty()) {
 607     if (strong_code_roots_length > 0) {
 608       log_error(gc, verify)("region [" PTR_FORMAT "," PTR_FORMAT "] is empty but has " SIZE_FORMAT " code root entries",
 609                             p2i(bottom()), p2i(end()), strong_code_roots_length);
 610       *failures = true;
 611     }
 612     return;
 613   }
 614 
 615   if (is_continues_humongous()) {
 616     if (strong_code_roots_length > 0) {
 617       log_error(gc, verify)("region " HR_FORMAT " is a continuation of a humongous region but has " SIZE_FORMAT " code root entries",
 618                             HR_FORMAT_PARAMS(this), strong_code_roots_length);
 619       *failures = true;
 620     }
 621     return;
 622   }
 623 
 624   VerifyStrongCodeRootCodeBlobClosure cb_cl(this);
 625   strong_code_roots_do(&cb_cl);
 626 
 627   if (cb_cl.failures()) {
 628     *failures = true;
 629   }
 630 }
 631 
 632 void HeapRegion::print() const { print_on(tty); }
 633 void HeapRegion::print_on(outputStream* st) const {
 634   st->print("|%4u", this->_hrm_index);
 635   st->print("|" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT,
 636             p2i(bottom()), p2i(top()), p2i(end()));
 637   st->print("|%3d%%", (int) ((double) used() * 100 / capacity()));
 638   st->print("|%2s", get_short_type_str());
 639   if (in_collection_set()) {
 640     st->print("|CS");
 641   } else {
 642     st->print("|  ");
 643   }
 644   st->print("|TS%3u", _gc_time_stamp);
 645   st->print("|AC%3u", allocation_context());
 646   st->print_cr("|TAMS " PTR_FORMAT ", " PTR_FORMAT "|",
 647                p2i(prev_top_at_mark_start()), p2i(next_top_at_mark_start()));
 648 }
 649 
 650 class G1VerificationClosure : public OopClosure {
 651 protected:
 652   G1CollectedHeap* _g1h;
 653   CardTableModRefBS* _bs;
 654   oop _containing_obj;
 655   bool _failures;
 656   int _n_failures;
 657   VerifyOption _vo;
 658 public:
 659   // _vo == UsePrevMarking -> use "prev" marking information,
 660   // _vo == UseNextMarking -> use "next" marking information,
 661   // _vo == UseMarkWord    -> use mark word from object header.
 662   G1VerificationClosure(G1CollectedHeap* g1h, VerifyOption vo) :
 663     _g1h(g1h), _bs(barrier_set_cast<CardTableModRefBS>(g1h->barrier_set())),
 664     _containing_obj(NULL), _failures(false), _n_failures(0), _vo(vo) {
 665   }
 666 
 667   void set_containing_obj(oop obj) {
 668     _containing_obj = obj;
 669   }
 670 
 671   bool failures() { return _failures; }
 672   int n_failures() { return _n_failures; }
 673 
 674   void print_object(outputStream* out, oop obj) {
 675 #ifdef PRODUCT
 676     Klass* k = obj->klass();
 677     const char* class_name = k->external_name();
 678     out->print_cr("class name %s", class_name);
 679 #else // PRODUCT
 680     obj->print_on(out);
 681 #endif // PRODUCT
 682   }
 683 };
 684 
 685 class VerifyLiveClosure : public G1VerificationClosure {
 686 public:
 687   VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) : G1VerificationClosure(g1h, vo) {}
 688   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
 689   virtual void do_oop(oop* p) { do_oop_work(p); }
 690 
 691   template <class T>
 692   void do_oop_work(T* p) {
 693     assert(_containing_obj != NULL, "Precondition");
 694     assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
 695       "Precondition");
 696     verify_liveness(p);
 697   }
 698 
 699   template <class T>
 700   void verify_liveness(T* p) {
 701     T heap_oop = oopDesc::load_heap_oop(p);
 702     Log(gc, verify) log;
 703     if (!oopDesc::is_null(heap_oop)) {
 704       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
 705       bool failed = false;
 706       if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) {
 707         MutexLockerEx x(ParGCRareEvent_lock,
 708           Mutex::_no_safepoint_check_flag);
 709 
 710         if (!_failures) {
 711           log.error("----------");
 712         }
 713         ResourceMark rm;
 714         if (!_g1h->is_in_closed_subset(obj)) {
 715           HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
 716           log.error("Field " PTR_FORMAT " of live obj " PTR_FORMAT " in region [" PTR_FORMAT ", " PTR_FORMAT ")",
 717             p2i(p), p2i(_containing_obj), p2i(from->bottom()), p2i(from->end()));
 718           print_object(log.error_stream(), _containing_obj);
 719           log.error("points to obj " PTR_FORMAT " not in the heap", p2i(obj));
 720         } else {
 721           HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
 722           HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj);
 723           log.error("Field " PTR_FORMAT " of live obj " PTR_FORMAT " in region [" PTR_FORMAT ", " PTR_FORMAT ")",
 724             p2i(p), p2i(_containing_obj), p2i(from->bottom()), p2i(from->end()));
 725           print_object(log.error_stream(), _containing_obj);
 726           log.error("points to dead obj " PTR_FORMAT " in region [" PTR_FORMAT ", " PTR_FORMAT ")",
 727             p2i(obj), p2i(to->bottom()), p2i(to->end()));
 728           print_object(log.error_stream(), obj);
 729         }
 730         log.error("----------");
 731         _failures = true;
 732         failed = true;
 733         _n_failures++;
 734       }
 735     }
 736   }
 737 };
 738 
 739 class VerifyRemSetClosure : public G1VerificationClosure {
 740 public:
 741   VerifyRemSetClosure(G1CollectedHeap* g1h, VerifyOption vo) : G1VerificationClosure(g1h, vo) {}
 742   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
 743   virtual void do_oop(oop* p) { do_oop_work(p); }
 744 
 745   template <class T>
 746   void do_oop_work(T* p) {
 747     assert(_containing_obj != NULL, "Precondition");
 748     assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
 749       "Precondition");
 750     verify_remembered_set(p);
 751   }
 752 
 753   template <class T>
 754   void verify_remembered_set(T* p) {
 755     T heap_oop = oopDesc::load_heap_oop(p);
 756     Log(gc, verify) log;
 757     if (!oopDesc::is_null(heap_oop)) {
 758       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
 759       bool failed = false;
 760       HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
 761       HeapRegion* to = _g1h->heap_region_containing(obj);
 762       if (from != NULL && to != NULL &&
 763         from != to &&
 764         !to->is_pinned()) {
 765         jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
 766         jbyte cv_field = *_bs->byte_for_const(p);
 767         const jbyte dirty = CardTableModRefBS::dirty_card_val();
 768 
 769         bool is_bad = !(from->is_young()
 770           || to->rem_set()->contains_reference(p)
 771           || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
 772           (_containing_obj->is_objArray() ?
 773           cv_field == dirty
 774           : cv_obj == dirty || cv_field == dirty));
 775         if (is_bad) {
 776           MutexLockerEx x(ParGCRareEvent_lock,
 777             Mutex::_no_safepoint_check_flag);
 778 
 779           if (!_failures) {
 780             log.error("----------");
 781           }
 782           log.error("Missing rem set entry:");
 783           log.error("Field " PTR_FORMAT " of obj " PTR_FORMAT ", in region " HR_FORMAT,
 784             p2i(p), p2i(_containing_obj), HR_FORMAT_PARAMS(from));
 785           ResourceMark rm;
 786           _containing_obj->print_on(log.error_stream());
 787           log.error("points to obj " PTR_FORMAT " in region " HR_FORMAT, p2i(obj), HR_FORMAT_PARAMS(to));
 788           if (obj->is_oop()) {
 789             obj->print_on(log.error_stream());
 790           }
 791           log.error("Obj head CTE = %d, field CTE = %d.", cv_obj, cv_field);
 792           log.error("----------");
 793           _failures = true;
 794           if (!failed) _n_failures++;
 795         }
 796       }
 797     }
 798   }
 799 };
 800 
 801 // This really ought to be commoned up into OffsetTableContigSpace somehow.
 802 // We would need a mechanism to make that code skip dead objects.
 803 
 804 void HeapRegion::verify(VerifyOption vo,
 805                         bool* failures) const {
 806   G1CollectedHeap* g1 = G1CollectedHeap::heap();
 807   *failures = false;
 808   HeapWord* p = bottom();
 809   HeapWord* prev_p = NULL;
 810   VerifyLiveClosure vl_cl(g1, vo);
 811   VerifyRemSetClosure vr_cl(g1, vo);
 812   bool is_region_humongous = is_humongous();
 813   size_t object_num = 0;
 814   while (p < top()) {
 815     oop obj = oop(p);
 816     size_t obj_size = block_size(p);
 817     object_num += 1;
 818 
 819     if (!g1->is_obj_dead_cond(obj, this, vo)) {
 820       if (obj->is_oop()) {
 821         Klass* klass = obj->klass();
 822         bool is_metaspace_object = Metaspace::contains(klass) ||
 823                                    (vo == VerifyOption_G1UsePrevMarking &&
 824                                    ClassLoaderDataGraph::unload_list_contains(klass));
 825         if (!is_metaspace_object) {
 826           log_error(gc, verify)("klass " PTR_FORMAT " of object " PTR_FORMAT " "
 827                                 "not metadata", p2i(klass), p2i(obj));
 828           *failures = true;
 829           return;
 830         } else if (!klass->is_klass()) {
 831           log_error(gc, verify)("klass " PTR_FORMAT " of object " PTR_FORMAT " "
 832                                 "not a klass", p2i(klass), p2i(obj));
 833           *failures = true;
 834           return;
 835         } else {
 836           vl_cl.set_containing_obj(obj);
 837           if (!g1->collector_state()->full_collection() || G1VerifyRSetsDuringFullGC) {
 838             // verify liveness and rem_set
 839             vr_cl.set_containing_obj(obj);
 840             G1Mux2Closure mux(&vl_cl, &vr_cl);
 841             obj->oop_iterate_no_header(&mux);
 842 
 843             if (vr_cl.failures()) {
 844               *failures = true;
 845             }
 846             if (G1MaxVerifyFailures >= 0 &&
 847               vr_cl.n_failures() >= G1MaxVerifyFailures) {
 848               return;
 849             }
 850           } else {
 851             // verify only liveness
 852             obj->oop_iterate_no_header(&vl_cl);
 853           }
 854           if (vl_cl.failures()) {
 855             *failures = true;
 856           }
 857           if (G1MaxVerifyFailures >= 0 &&
 858               vl_cl.n_failures() >= G1MaxVerifyFailures) {
 859             return;
 860           }
 861         }
 862       } else {
 863         log_error(gc, verify)(PTR_FORMAT " not an oop", p2i(obj));
 864         *failures = true;
 865         return;
 866       }
 867     }
 868     prev_p = p;
 869     p += obj_size;
 870   }
 871 
 872   if (!is_young() && !is_empty()) {
 873     _bot_part.verify();
 874   }
 875 
 876   if (is_region_humongous) {
 877     oop obj = oop(this->humongous_start_region()->bottom());
 878     if ((HeapWord*)obj > bottom() || (HeapWord*)obj + obj->size() < bottom()) {
 879       log_error(gc, verify)("this humongous region is not part of its' humongous object " PTR_FORMAT, p2i(obj));
 880       *failures = true;
 881       return;
 882     }
 883   }
 884 
 885   if (!is_region_humongous && p != top()) {
 886     log_error(gc, verify)("end of last object " PTR_FORMAT " "
 887                           "does not match top " PTR_FORMAT, p2i(p), p2i(top()));
 888     *failures = true;
 889     return;
 890   }
 891 
 892   HeapWord* the_end = end();
 893   // Do some extra BOT consistency checking for addresses in the
 894   // range [top, end). BOT look-ups in this range should yield
 895   // top. No point in doing that if top == end (there's nothing there).
 896   if (p < the_end) {
 897     // Look up top
 898     HeapWord* addr_1 = p;
 899     HeapWord* b_start_1 = _bot_part.block_start_const(addr_1);
 900     if (b_start_1 != p) {
 901       log_error(gc, verify)("BOT look up for top: " PTR_FORMAT " "
 902                             " yielded " PTR_FORMAT ", expecting " PTR_FORMAT,
 903                             p2i(addr_1), p2i(b_start_1), p2i(p));
 904       *failures = true;
 905       return;
 906     }
 907 
 908     // Look up top + 1
 909     HeapWord* addr_2 = p + 1;
 910     if (addr_2 < the_end) {
 911       HeapWord* b_start_2 = _bot_part.block_start_const(addr_2);
 912       if (b_start_2 != p) {
 913         log_error(gc, verify)("BOT look up for top + 1: " PTR_FORMAT " "
 914                               " yielded " PTR_FORMAT ", expecting " PTR_FORMAT,
 915                               p2i(addr_2), p2i(b_start_2), p2i(p));
 916         *failures = true;
 917         return;
 918       }
 919     }
 920 
 921     // Look up an address between top and end
 922     size_t diff = pointer_delta(the_end, p) / 2;
 923     HeapWord* addr_3 = p + diff;
 924     if (addr_3 < the_end) {
 925       HeapWord* b_start_3 = _bot_part.block_start_const(addr_3);
 926       if (b_start_3 != p) {
 927         log_error(gc, verify)("BOT look up for top + diff: " PTR_FORMAT " "
 928                               " yielded " PTR_FORMAT ", expecting " PTR_FORMAT,
 929                               p2i(addr_3), p2i(b_start_3), p2i(p));
 930         *failures = true;
 931         return;
 932       }
 933     }
 934 
 935     // Look up end - 1
 936     HeapWord* addr_4 = the_end - 1;
 937     HeapWord* b_start_4 = _bot_part.block_start_const(addr_4);
 938     if (b_start_4 != p) {
 939       log_error(gc, verify)("BOT look up for end - 1: " PTR_FORMAT " "
 940                             " yielded " PTR_FORMAT ", expecting " PTR_FORMAT,
 941                             p2i(addr_4), p2i(b_start_4), p2i(p));
 942       *failures = true;
 943       return;
 944     }
 945   }
 946 
 947   verify_strong_code_roots(vo, failures);
 948 }
 949 
 950 void HeapRegion::verify() const {
 951   bool dummy = false;
 952   verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
 953 }
 954 
 955 void HeapRegion::verify_rem_set(VerifyOption vo, bool* failures) const {
 956   G1CollectedHeap* g1 = G1CollectedHeap::heap();
 957   *failures = false;
 958   HeapWord* p = bottom();
 959   HeapWord* prev_p = NULL;
 960   VerifyRemSetClosure vr_cl(g1, vo);
 961   while (p < top()) {
 962     oop obj = oop(p);
 963     size_t obj_size = block_size(p);
 964 
 965     if (!g1->is_obj_dead_cond(obj, this, vo)) {
 966       if (obj->is_oop()) {
 967         vr_cl.set_containing_obj(obj);
 968         obj->oop_iterate_no_header(&vr_cl);
 969 
 970         if (vr_cl.failures()) {
 971           *failures = true;
 972         }
 973         if (G1MaxVerifyFailures >= 0 &&
 974           vr_cl.n_failures() >= G1MaxVerifyFailures) {
 975           return;
 976         }
 977       } else {
 978         log_error(gc, verify)(PTR_FORMAT " not an oop", p2i(obj));
 979         *failures = true;
 980         return;
 981       }
 982     }
 983 
 984     prev_p = p;
 985     p += obj_size;
 986   }
 987 }
 988 
 989 void HeapRegion::verify_rem_set() const {
 990   bool failures = false;
 991   verify_rem_set(VerifyOption_G1UsePrevMarking, &failures);
 992   guarantee(!failures, "HeapRegion RemSet verification failed");
 993 }
 994 
 995 void HeapRegion::prepare_for_compaction(CompactPoint* cp) {
 996   scan_and_forward(this, cp);
 997 }
 998 
 999 // G1OffsetTableContigSpace code; copied from space.cpp.  Hope this can go
1000 // away eventually.
1001 
1002 void G1ContiguousSpace::clear(bool mangle_space) {
1003   set_top(bottom());
1004   _scan_top = bottom();
1005   CompactibleSpace::clear(mangle_space);
1006   reset_bot();
1007 }
1008 
1009 #ifndef PRODUCT
1010 void G1ContiguousSpace::mangle_unused_area() {
1011   mangle_unused_area_complete();
1012 }
1013 
1014 void G1ContiguousSpace::mangle_unused_area_complete() {
1015   SpaceMangler::mangle_region(MemRegion(top(), end()));
1016 }
1017 #endif
1018 
1019 void G1ContiguousSpace::print() const {
1020   print_short();
1021   tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
1022                 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
1023                 p2i(bottom()), p2i(top()), p2i(_bot_part.threshold()), p2i(end()));
1024 }
1025 
1026 HeapWord* G1ContiguousSpace::initialize_threshold() {
1027   return _bot_part.initialize_threshold();
1028 }
1029 
1030 HeapWord* G1ContiguousSpace::cross_threshold(HeapWord* start,
1031                                                     HeapWord* end) {
1032   _bot_part.alloc_block(start, end);
1033   return _bot_part.threshold();
1034 }
1035 
1036 HeapWord* G1ContiguousSpace::scan_top() const {
1037   G1CollectedHeap* g1h = G1CollectedHeap::heap();
1038   HeapWord* local_top = top();
1039   OrderAccess::loadload();
1040   const unsigned local_time_stamp = _gc_time_stamp;
1041   assert(local_time_stamp <= g1h->get_gc_time_stamp(), "invariant");
1042   if (local_time_stamp < g1h->get_gc_time_stamp()) {
1043     return local_top;
1044   } else {
1045     return _scan_top;
1046   }
1047 }
1048 
1049 void G1ContiguousSpace::record_timestamp() {
1050   G1CollectedHeap* g1h = G1CollectedHeap::heap();
1051   uint curr_gc_time_stamp = g1h->get_gc_time_stamp();
1052 
1053   if (_gc_time_stamp < curr_gc_time_stamp) {
1054     // Setting the time stamp here tells concurrent readers to look at
1055     // scan_top to know the maximum allowed address to look at.
1056 
1057     // scan_top should be bottom for all regions except for the
1058     // retained old alloc region which should have scan_top == top
1059     HeapWord* st = _scan_top;
1060     guarantee(st == _bottom || st == _top, "invariant");
1061 
1062     _gc_time_stamp = curr_gc_time_stamp;
1063   }
1064 }
1065 
1066 void G1ContiguousSpace::record_retained_region() {
1067   // scan_top is the maximum address where it's safe for the next gc to
1068   // scan this region.
1069   _scan_top = top();
1070 }
1071 
1072 void G1ContiguousSpace::safe_object_iterate(ObjectClosure* blk) {
1073   object_iterate(blk);
1074 }
1075 
1076 void G1ContiguousSpace::object_iterate(ObjectClosure* blk) {
1077   HeapWord* p = bottom();
1078   while (p < top()) {
1079     if (block_is_obj(p)) {
1080       blk->do_object(oop(p));
1081     }
1082     p += block_size(p);
1083   }
1084 }
1085 
1086 G1ContiguousSpace::G1ContiguousSpace(G1BlockOffsetTable* bot) :
1087   _bot_part(bot, this),
1088   _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
1089   _gc_time_stamp(0)
1090 {
1091 }
1092 
1093 void G1ContiguousSpace::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
1094   CompactibleSpace::initialize(mr, clear_space, mangle_space);
1095   _top = bottom();
1096   _scan_top = bottom();
1097   set_saved_mark_word(NULL);
1098   reset_bot();
1099 }
1100