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_young_region(NULL),
 291     _next_dirty_cards_region(NULL), _next(NULL), _prev(NULL),
 292 #ifdef ASSERT
 293     _containing_set(NULL),
 294 #endif // ASSERT
 295      _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),
 296     _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),
 297     _predicted_bytes_to_copy(0)
 298 {
 299   _rem_set = new HeapRegionRemSet(bot, this);
 300 
 301   initialize(mr);
 302 }
 303 
 304 void HeapRegion::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
 305   assert(_rem_set->is_empty(), "Remembered set must be empty");
 306 
 307   G1ContiguousSpace::initialize(mr, clear_space, mangle_space);
 308 
 309   hr_clear(false /*par*/, false /*clear_space*/);
 310   set_top(bottom());
 311   record_timestamp();
 312 }
 313 
 314 void HeapRegion::report_region_type_change(G1HeapRegionTraceType::Type to) {
 315   HeapRegionTracer::send_region_type_change(_hrm_index,
 316                                             get_trace_type(),
 317                                             to,
 318                                             (uintptr_t)bottom(),
 319                                             used(),
 320                                             (uint)allocation_context());
 321 }
 322 
 323 CompactibleSpace* HeapRegion::next_compaction_space() const {
 324   return G1CollectedHeap::heap()->next_compaction_region(this);
 325 }
 326 
 327 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,
 328                                                     bool during_conc_mark) {
 329   // We always recreate the prev marking info and we'll explicitly
 330   // mark all objects we find to be self-forwarded on the prev
 331   // bitmap. So all objects need to be below PTAMS.
 332   _prev_marked_bytes = 0;
 333 
 334   if (during_initial_mark) {
 335     // During initial-mark, we'll also explicitly mark all objects
 336     // we find to be self-forwarded on the next bitmap. So all
 337     // objects need to be below NTAMS.
 338     _next_top_at_mark_start = top();
 339     _next_marked_bytes = 0;
 340   } else if (during_conc_mark) {
 341     // During concurrent mark, all objects in the CSet (including
 342     // the ones we find to be self-forwarded) are implicitly live.
 343     // So all objects need to be above NTAMS.
 344     _next_top_at_mark_start = bottom();
 345     _next_marked_bytes = 0;
 346   }
 347 }
 348 
 349 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark,
 350                                                   bool during_conc_mark,
 351                                                   size_t marked_bytes) {
 352   assert(marked_bytes <= used(),
 353          "marked: " SIZE_FORMAT " used: " SIZE_FORMAT, marked_bytes, used());
 354   _prev_top_at_mark_start = top();
 355   _prev_marked_bytes = marked_bytes;
 356 }
 357 
 358 HeapWord*
 359 HeapRegion::object_iterate_mem_careful(MemRegion mr,
 360                                                  ObjectClosure* cl) {
 361   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 362   // We used to use "block_start_careful" here.  But we're actually happy
 363   // to update the BOT while we do this...
 364   HeapWord* cur = block_start(mr.start());
 365   mr = mr.intersection(used_region());
 366   if (mr.is_empty()) return NULL;
 367   // Otherwise, find the obj that extends onto mr.start().
 368 
 369   assert(cur <= mr.start()
 370          && (oop(cur)->klass_or_null() == NULL ||
 371              cur + oop(cur)->size() > mr.start()),
 372          "postcondition of block_start");
 373   oop obj;
 374   while (cur < mr.end()) {
 375     obj = oop(cur);
 376     if (obj->klass_or_null() == NULL) {
 377       // Ran into an unparseable point.
 378       return cur;
 379     } else if (!g1h->is_obj_dead(obj)) {
 380       cl->do_object(obj);
 381     }
 382     cur += block_size(cur);
 383   }
 384   return NULL;
 385 }
 386 
 387 HeapWord*
 388 HeapRegion::
 389 oops_on_card_seq_iterate_careful(MemRegion mr,
 390                                  FilterOutOfRegionClosure* cl,
 391                                  bool filter_young,
 392                                  jbyte* card_ptr) {
 393   // Currently, we should only have to clean the card if filter_young
 394   // is true and vice versa.
 395   if (filter_young) {
 396     assert(card_ptr != NULL, "pre-condition");
 397   } else {
 398     assert(card_ptr == NULL, "pre-condition");
 399   }
 400   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 401 
 402   // If we're within a stop-world GC, then we might look at a card in a
 403   // GC alloc region that extends onto a GC LAB, which may not be
 404   // parseable.  Stop such at the "scan_top" of the region.
 405   if (g1h->is_gc_active()) {
 406     mr = mr.intersection(MemRegion(bottom(), scan_top()));
 407   } else {
 408     mr = mr.intersection(used_region());
 409   }
 410   if (mr.is_empty()) return NULL;
 411   // Otherwise, find the obj that extends onto mr.start().
 412 
 413   // The intersection of the incoming mr (for the card) and the
 414   // allocated part of the region is non-empty. This implies that
 415   // we have actually allocated into this region. The code in
 416   // G1CollectedHeap.cpp that allocates a new region sets the
 417   // is_young tag on the region before allocating. Thus we
 418   // safely know if this region is young.
 419   if (is_young() && filter_young) {
 420     return NULL;
 421   }
 422 
 423   assert(!is_young(), "check value of filter_young");
 424 
 425   // We can only clean the card here, after we make the decision that
 426   // the card is not young. And we only clean the card if we have been
 427   // asked to (i.e., card_ptr != NULL).
 428   if (card_ptr != NULL) {
 429     *card_ptr = CardTableModRefBS::clean_card_val();
 430     // We must complete this write before we do any of the reads below.
 431     OrderAccess::storeload();
 432   }
 433 
 434   // Cache the boundaries of the memory region in some const locals
 435   HeapWord* const start = mr.start();
 436   HeapWord* const end = mr.end();
 437 
 438   // We used to use "block_start_careful" here.  But we're actually happy
 439   // to update the BOT while we do this...
 440   HeapWord* cur = block_start(start);
 441   assert(cur <= start, "Postcondition");
 442 
 443   oop obj;
 444 
 445   HeapWord* next = cur;
 446   do {
 447     cur = next;
 448     obj = oop(cur);
 449     if (obj->klass_or_null() == NULL) {
 450       // Ran into an unparseable point.
 451       return cur;
 452     }
 453     // Otherwise...
 454     next = cur + block_size(cur);
 455   } while (next <= start);
 456 
 457   // If we finish the above loop...We have a parseable object that
 458   // begins on or before the start of the memory region, and ends
 459   // inside or spans the entire region.
 460   assert(cur <= start, "Loop postcondition");
 461   assert(obj->klass_or_null() != NULL, "Loop postcondition");
 462 
 463   do {
 464     obj = oop(cur);
 465     assert((cur + block_size(cur)) > (HeapWord*)obj, "Loop invariant");
 466     if (obj->klass_or_null() == NULL) {
 467       // Ran into an unparseable point.
 468       return cur;
 469     }
 470 
 471     // Advance the current pointer. "obj" still points to the object to iterate.
 472     cur = cur + block_size(cur);
 473 
 474     if (!g1h->is_obj_dead(obj)) {
 475       // Non-objArrays are sometimes marked imprecise at the object start. We
 476       // always need to iterate over them in full.
 477       // We only iterate over object arrays in full if they are completely contained
 478       // in the memory region.
 479       if (!obj->is_objArray() || (((HeapWord*)obj) >= start && cur <= end)) {
 480         obj->oop_iterate(cl);
 481       } else {
 482         obj->oop_iterate(cl, mr);
 483       }
 484     }
 485   } while (cur < end);
 486 
 487   return NULL;
 488 }
 489 
 490 // Code roots support
 491 
 492 void HeapRegion::add_strong_code_root(nmethod* nm) {
 493   HeapRegionRemSet* hrrs = rem_set();
 494   hrrs->add_strong_code_root(nm);
 495 }
 496 
 497 void HeapRegion::add_strong_code_root_locked(nmethod* nm) {
 498   assert_locked_or_safepoint(CodeCache_lock);
 499   HeapRegionRemSet* hrrs = rem_set();
 500   hrrs->add_strong_code_root_locked(nm);
 501 }
 502 
 503 void HeapRegion::remove_strong_code_root(nmethod* nm) {
 504   HeapRegionRemSet* hrrs = rem_set();
 505   hrrs->remove_strong_code_root(nm);
 506 }
 507 
 508 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const {
 509   HeapRegionRemSet* hrrs = rem_set();
 510   hrrs->strong_code_roots_do(blk);
 511 }
 512 
 513 class VerifyStrongCodeRootOopClosure: public OopClosure {
 514   const HeapRegion* _hr;
 515   nmethod* _nm;
 516   bool _failures;
 517   bool _has_oops_in_region;
 518 
 519   template <class T> void do_oop_work(T* p) {
 520     T heap_oop = oopDesc::load_heap_oop(p);
 521     if (!oopDesc::is_null(heap_oop)) {
 522       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
 523 
 524       // Note: not all the oops embedded in the nmethod are in the
 525       // current region. We only look at those which are.
 526       if (_hr->is_in(obj)) {
 527         // Object is in the region. Check that its less than top
 528         if (_hr->top() <= (HeapWord*)obj) {
 529           // Object is above top
 530           log_error(gc, verify)("Object " PTR_FORMAT " in region [" PTR_FORMAT ", " PTR_FORMAT ") is above top " PTR_FORMAT,
 531                                p2i(obj), p2i(_hr->bottom()), p2i(_hr->end()), p2i(_hr->top()));
 532           _failures = true;
 533           return;
 534         }
 535         // Nmethod has at least one oop in the current region
 536         _has_oops_in_region = true;
 537       }
 538     }
 539   }
 540 
 541 public:
 542   VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm):
 543     _hr(hr), _failures(false), _has_oops_in_region(false) {}
 544 
 545   void do_oop(narrowOop* p) { do_oop_work(p); }
 546   void do_oop(oop* p)       { do_oop_work(p); }
 547 
 548   bool failures()           { return _failures; }
 549   bool has_oops_in_region() { return _has_oops_in_region; }
 550 };
 551 
 552 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
 553   const HeapRegion* _hr;
 554   bool _failures;
 555 public:
 556   VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) :
 557     _hr(hr), _failures(false) {}
 558 
 559   void do_code_blob(CodeBlob* cb) {
 560     nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
 561     if (nm != NULL) {
 562       // Verify that the nemthod is live
 563       if (!nm->is_alive()) {
 564         log_error(gc, verify)("region [" PTR_FORMAT "," PTR_FORMAT "] has dead nmethod " PTR_FORMAT " in its strong code roots",
 565                               p2i(_hr->bottom()), p2i(_hr->end()), p2i(nm));
 566         _failures = true;
 567       } else {
 568         VerifyStrongCodeRootOopClosure oop_cl(_hr, nm);
 569         nm->oops_do(&oop_cl);
 570         if (!oop_cl.has_oops_in_region()) {
 571           log_error(gc, verify)("region [" PTR_FORMAT "," PTR_FORMAT "] has nmethod " PTR_FORMAT " in its strong code roots with no pointers into region",
 572                                 p2i(_hr->bottom()), p2i(_hr->end()), p2i(nm));
 573           _failures = true;
 574         } else if (oop_cl.failures()) {
 575           log_error(gc, verify)("region [" PTR_FORMAT "," PTR_FORMAT "] has other failures for nmethod " PTR_FORMAT,
 576                                 p2i(_hr->bottom()), p2i(_hr->end()), p2i(nm));
 577           _failures = true;
 578         }
 579       }
 580     }
 581   }
 582 
 583   bool failures()       { return _failures; }
 584 };
 585 
 586 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const {
 587   if (!G1VerifyHeapRegionCodeRoots) {
 588     // We're not verifying code roots.
 589     return;
 590   }
 591   if (vo == VerifyOption_G1UseMarkWord) {
 592     // Marking verification during a full GC is performed after class
 593     // unloading, code cache unloading, etc so the strong code roots
 594     // attached to each heap region are in an inconsistent state. They won't
 595     // be consistent until the strong code roots are rebuilt after the
 596     // actual GC. Skip verifying the strong code roots in this particular
 597     // time.
 598     assert(VerifyDuringGC, "only way to get here");
 599     return;
 600   }
 601 
 602   HeapRegionRemSet* hrrs = rem_set();
 603   size_t strong_code_roots_length = hrrs->strong_code_roots_list_length();
 604 
 605   // if this region is empty then there should be no entries
 606   // on its strong code root list
 607   if (is_empty()) {
 608     if (strong_code_roots_length > 0) {
 609       log_error(gc, verify)("region [" PTR_FORMAT "," PTR_FORMAT "] is empty but has " SIZE_FORMAT " code root entries",
 610                             p2i(bottom()), p2i(end()), strong_code_roots_length);
 611       *failures = true;
 612     }
 613     return;
 614   }
 615 
 616   if (is_continues_humongous()) {
 617     if (strong_code_roots_length > 0) {
 618       log_error(gc, verify)("region " HR_FORMAT " is a continuation of a humongous region but has " SIZE_FORMAT " code root entries",
 619                             HR_FORMAT_PARAMS(this), strong_code_roots_length);
 620       *failures = true;
 621     }
 622     return;
 623   }
 624 
 625   VerifyStrongCodeRootCodeBlobClosure cb_cl(this);
 626   strong_code_roots_do(&cb_cl);
 627 
 628   if (cb_cl.failures()) {
 629     *failures = true;
 630   }
 631 }
 632 
 633 void HeapRegion::print() const { print_on(tty); }
 634 void HeapRegion::print_on(outputStream* st) const {
 635   st->print("|%4u", this->_hrm_index);
 636   st->print("|" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT,
 637             p2i(bottom()), p2i(top()), p2i(end()));
 638   st->print("|%3d%%", (int) ((double) used() * 100 / capacity()));
 639   st->print("|%2s", get_short_type_str());
 640   if (in_collection_set()) {
 641     st->print("|CS");
 642   } else {
 643     st->print("|  ");
 644   }
 645   st->print("|TS%3u", _gc_time_stamp);
 646   st->print("|AC%3u", allocation_context());
 647   st->print_cr("|TAMS " PTR_FORMAT ", " PTR_FORMAT "|",
 648                p2i(prev_top_at_mark_start()), p2i(next_top_at_mark_start()));
 649 }
 650 
 651 class G1VerificationClosure : public OopClosure {
 652 protected:
 653   G1CollectedHeap* _g1h;
 654   CardTableModRefBS* _bs;
 655   oop _containing_obj;
 656   bool _failures;
 657   int _n_failures;
 658   VerifyOption _vo;
 659 public:
 660   // _vo == UsePrevMarking -> use "prev" marking information,
 661   // _vo == UseNextMarking -> use "next" marking information,
 662   // _vo == UseMarkWord    -> use mark word from object header.
 663   G1VerificationClosure(G1CollectedHeap* g1h, VerifyOption vo) :
 664     _g1h(g1h), _bs(barrier_set_cast<CardTableModRefBS>(g1h->barrier_set())),
 665     _containing_obj(NULL), _failures(false), _n_failures(0), _vo(vo) {
 666   }
 667 
 668   void set_containing_obj(oop obj) {
 669     _containing_obj = obj;
 670   }
 671 
 672   bool failures() { return _failures; }
 673   int n_failures() { return _n_failures; }
 674 
 675   void print_object(outputStream* out, oop obj) {
 676 #ifdef PRODUCT
 677     Klass* k = obj->klass();
 678     const char* class_name = k->external_name();
 679     out->print_cr("class name %s", class_name);
 680 #else // PRODUCT
 681     obj->print_on(out);
 682 #endif // PRODUCT
 683   }
 684 };
 685 
 686 class VerifyLiveClosure : public G1VerificationClosure {
 687 public:
 688   VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) : G1VerificationClosure(g1h, vo) {}
 689   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
 690   virtual void do_oop(oop* p) { do_oop_work(p); }
 691 
 692   template <class T>
 693   void do_oop_work(T* p) {
 694     assert(_containing_obj != NULL, "Precondition");
 695     assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
 696       "Precondition");
 697     verify_liveness(p);
 698   }
 699 
 700   template <class T>
 701   void verify_liveness(T* p) {
 702     T heap_oop = oopDesc::load_heap_oop(p);
 703     Log(gc, verify) log;
 704     if (!oopDesc::is_null(heap_oop)) {
 705       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
 706       bool failed = false;
 707       if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) {
 708         MutexLockerEx x(ParGCRareEvent_lock,
 709           Mutex::_no_safepoint_check_flag);
 710 
 711         if (!_failures) {
 712           log.error("----------");
 713         }
 714         ResourceMark rm;
 715         if (!_g1h->is_in_closed_subset(obj)) {
 716           HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
 717           log.error("Field " PTR_FORMAT " of live obj " PTR_FORMAT " in region [" PTR_FORMAT ", " PTR_FORMAT ")",
 718             p2i(p), p2i(_containing_obj), p2i(from->bottom()), p2i(from->end()));
 719           print_object(log.error_stream(), _containing_obj);
 720           log.error("points to obj " PTR_FORMAT " not in the heap", p2i(obj));
 721         } else {
 722           HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
 723           HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj);
 724           log.error("Field " PTR_FORMAT " of live obj " PTR_FORMAT " in region [" PTR_FORMAT ", " PTR_FORMAT ")",
 725             p2i(p), p2i(_containing_obj), p2i(from->bottom()), p2i(from->end()));
 726           print_object(log.error_stream(), _containing_obj);
 727           log.error("points to dead obj " PTR_FORMAT " in region [" PTR_FORMAT ", " PTR_FORMAT ")",
 728             p2i(obj), p2i(to->bottom()), p2i(to->end()));
 729           print_object(log.error_stream(), obj);
 730         }
 731         log.error("----------");
 732         _failures = true;
 733         failed = true;
 734         _n_failures++;
 735       }
 736     }
 737   }
 738 };
 739 
 740 class VerifyRemSetClosure : public G1VerificationClosure {
 741 public:
 742   VerifyRemSetClosure(G1CollectedHeap* g1h, VerifyOption vo) : G1VerificationClosure(g1h, vo) {}
 743   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
 744   virtual void do_oop(oop* p) { do_oop_work(p); }
 745 
 746   template <class T>
 747   void do_oop_work(T* p) {
 748     assert(_containing_obj != NULL, "Precondition");
 749     assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
 750       "Precondition");
 751     verify_remembered_set(p);
 752   }
 753 
 754   template <class T>
 755   void verify_remembered_set(T* p) {
 756     T heap_oop = oopDesc::load_heap_oop(p);
 757     Log(gc, verify) log;
 758     if (!oopDesc::is_null(heap_oop)) {
 759       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
 760       bool failed = false;
 761       HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
 762       HeapRegion* to = _g1h->heap_region_containing(obj);
 763       if (from != NULL && to != NULL &&
 764         from != to &&
 765         !to->is_pinned()) {
 766         jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
 767         jbyte cv_field = *_bs->byte_for_const(p);
 768         const jbyte dirty = CardTableModRefBS::dirty_card_val();
 769 
 770         bool is_bad = !(from->is_young()
 771           || to->rem_set()->contains_reference(p)
 772           || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
 773           (_containing_obj->is_objArray() ?
 774           cv_field == dirty
 775           : cv_obj == dirty || cv_field == dirty));
 776         if (is_bad) {
 777           MutexLockerEx x(ParGCRareEvent_lock,
 778             Mutex::_no_safepoint_check_flag);
 779 
 780           if (!_failures) {
 781             log.error("----------");
 782           }
 783           log.error("Missing rem set entry:");
 784           log.error("Field " PTR_FORMAT " of obj " PTR_FORMAT ", in region " HR_FORMAT,
 785             p2i(p), p2i(_containing_obj), HR_FORMAT_PARAMS(from));
 786           ResourceMark rm;
 787           _containing_obj->print_on(log.error_stream());
 788           log.error("points to obj " PTR_FORMAT " in region " HR_FORMAT, p2i(obj), HR_FORMAT_PARAMS(to));
 789           if (obj->is_oop()) {
 790             obj->print_on(log.error_stream());
 791           }
 792           log.error("Obj head CTE = %d, field CTE = %d.", cv_obj, cv_field);
 793           log.error("----------");
 794           _failures = true;
 795           if (!failed) _n_failures++;
 796         }
 797       }
 798     }
 799   }
 800 };
 801 
 802 // This really ought to be commoned up into OffsetTableContigSpace somehow.
 803 // We would need a mechanism to make that code skip dead objects.
 804 
 805 void HeapRegion::verify(VerifyOption vo,
 806                         bool* failures) const {
 807   G1CollectedHeap* g1 = G1CollectedHeap::heap();
 808   *failures = false;
 809   HeapWord* p = bottom();
 810   HeapWord* prev_p = NULL;
 811   VerifyLiveClosure vl_cl(g1, vo);
 812   VerifyRemSetClosure vr_cl(g1, vo);
 813   bool is_region_humongous = is_humongous();
 814   size_t object_num = 0;
 815   while (p < top()) {
 816     oop obj = oop(p);
 817     size_t obj_size = block_size(p);
 818     object_num += 1;
 819 
 820     if (!g1->is_obj_dead_cond(obj, this, vo)) {
 821       if (obj->is_oop()) {
 822         Klass* klass = obj->klass();
 823         bool is_metaspace_object = Metaspace::contains(klass) ||
 824                                    (vo == VerifyOption_G1UsePrevMarking &&
 825                                    ClassLoaderDataGraph::unload_list_contains(klass));
 826         if (!is_metaspace_object) {
 827           log_error(gc, verify)("klass " PTR_FORMAT " of object " PTR_FORMAT " "
 828                                 "not metadata", p2i(klass), p2i(obj));
 829           *failures = true;
 830           return;
 831         } else if (!klass->is_klass()) {
 832           log_error(gc, verify)("klass " PTR_FORMAT " of object " PTR_FORMAT " "
 833                                 "not a klass", p2i(klass), p2i(obj));
 834           *failures = true;
 835           return;
 836         } else {
 837           vl_cl.set_containing_obj(obj);
 838           if (!g1->collector_state()->full_collection() || G1VerifyRSetsDuringFullGC) {
 839             // verify liveness and rem_set
 840             vr_cl.set_containing_obj(obj);
 841             G1Mux2Closure mux(&vl_cl, &vr_cl);
 842             obj->oop_iterate_no_header(&mux);
 843 
 844             if (vr_cl.failures()) {
 845               *failures = true;
 846             }
 847             if (G1MaxVerifyFailures >= 0 &&
 848               vr_cl.n_failures() >= G1MaxVerifyFailures) {
 849               return;
 850             }
 851           } else {
 852             // verify only liveness
 853             obj->oop_iterate_no_header(&vl_cl);
 854           }
 855           if (vl_cl.failures()) {
 856             *failures = true;
 857           }
 858           if (G1MaxVerifyFailures >= 0 &&
 859               vl_cl.n_failures() >= G1MaxVerifyFailures) {
 860             return;
 861           }
 862         }
 863       } else {
 864         log_error(gc, verify)(PTR_FORMAT " not an oop", p2i(obj));
 865         *failures = true;
 866         return;
 867       }
 868     }
 869     prev_p = p;
 870     p += obj_size;
 871   }
 872 
 873   if (!is_young() && !is_empty()) {
 874     _bot_part.verify();
 875   }
 876 
 877   if (is_region_humongous) {
 878     oop obj = oop(this->humongous_start_region()->bottom());
 879     if ((HeapWord*)obj > bottom() || (HeapWord*)obj + obj->size() < bottom()) {
 880       log_error(gc, verify)("this humongous region is not part of its' humongous object " PTR_FORMAT, p2i(obj));
 881       *failures = true;
 882       return;
 883     }
 884   }
 885 
 886   if (!is_region_humongous && p != top()) {
 887     log_error(gc, verify)("end of last object " PTR_FORMAT " "
 888                           "does not match top " PTR_FORMAT, p2i(p), p2i(top()));
 889     *failures = true;
 890     return;
 891   }
 892 
 893   HeapWord* the_end = end();
 894   // Do some extra BOT consistency checking for addresses in the
 895   // range [top, end). BOT look-ups in this range should yield
 896   // top. No point in doing that if top == end (there's nothing there).
 897   if (p < the_end) {
 898     // Look up top
 899     HeapWord* addr_1 = p;
 900     HeapWord* b_start_1 = _bot_part.block_start_const(addr_1);
 901     if (b_start_1 != p) {
 902       log_error(gc, verify)("BOT look up for top: " PTR_FORMAT " "
 903                             " yielded " PTR_FORMAT ", expecting " PTR_FORMAT,
 904                             p2i(addr_1), p2i(b_start_1), p2i(p));
 905       *failures = true;
 906       return;
 907     }
 908 
 909     // Look up top + 1
 910     HeapWord* addr_2 = p + 1;
 911     if (addr_2 < the_end) {
 912       HeapWord* b_start_2 = _bot_part.block_start_const(addr_2);
 913       if (b_start_2 != p) {
 914         log_error(gc, verify)("BOT look up for top + 1: " PTR_FORMAT " "
 915                               " yielded " PTR_FORMAT ", expecting " PTR_FORMAT,
 916                               p2i(addr_2), p2i(b_start_2), p2i(p));
 917         *failures = true;
 918         return;
 919       }
 920     }
 921 
 922     // Look up an address between top and end
 923     size_t diff = pointer_delta(the_end, p) / 2;
 924     HeapWord* addr_3 = p + diff;
 925     if (addr_3 < the_end) {
 926       HeapWord* b_start_3 = _bot_part.block_start_const(addr_3);
 927       if (b_start_3 != p) {
 928         log_error(gc, verify)("BOT look up for top + diff: " PTR_FORMAT " "
 929                               " yielded " PTR_FORMAT ", expecting " PTR_FORMAT,
 930                               p2i(addr_3), p2i(b_start_3), p2i(p));
 931         *failures = true;
 932         return;
 933       }
 934     }
 935 
 936     // Look up end - 1
 937     HeapWord* addr_4 = the_end - 1;
 938     HeapWord* b_start_4 = _bot_part.block_start_const(addr_4);
 939     if (b_start_4 != p) {
 940       log_error(gc, verify)("BOT look up for end - 1: " PTR_FORMAT " "
 941                             " yielded " PTR_FORMAT ", expecting " PTR_FORMAT,
 942                             p2i(addr_4), p2i(b_start_4), p2i(p));
 943       *failures = true;
 944       return;
 945     }
 946   }
 947 
 948   verify_strong_code_roots(vo, failures);
 949 }
 950 
 951 void HeapRegion::verify() const {
 952   bool dummy = false;
 953   verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
 954 }
 955 
 956 void HeapRegion::verify_rem_set(VerifyOption vo, bool* failures) const {
 957   G1CollectedHeap* g1 = G1CollectedHeap::heap();
 958   *failures = false;
 959   HeapWord* p = bottom();
 960   HeapWord* prev_p = NULL;
 961   VerifyRemSetClosure vr_cl(g1, vo);
 962   while (p < top()) {
 963     oop obj = oop(p);
 964     size_t obj_size = block_size(p);
 965 
 966     if (!g1->is_obj_dead_cond(obj, this, vo)) {
 967       if (obj->is_oop()) {
 968         vr_cl.set_containing_obj(obj);
 969         obj->oop_iterate_no_header(&vr_cl);
 970 
 971         if (vr_cl.failures()) {
 972           *failures = true;
 973         }
 974         if (G1MaxVerifyFailures >= 0 &&
 975           vr_cl.n_failures() >= G1MaxVerifyFailures) {
 976           return;
 977         }
 978       } else {
 979         log_error(gc, verify)(PTR_FORMAT " not an oop", p2i(obj));
 980         *failures = true;
 981         return;
 982       }
 983     }
 984 
 985     prev_p = p;
 986     p += obj_size;
 987   }
 988 }
 989 
 990 void HeapRegion::verify_rem_set() const {
 991   bool failures = false;
 992   verify_rem_set(VerifyOption_G1UsePrevMarking, &failures);
 993   guarantee(!failures, "HeapRegion RemSet verification failed");
 994 }
 995 
 996 void HeapRegion::prepare_for_compaction(CompactPoint* cp) {
 997   scan_and_forward(this, cp);
 998 }
 999 
1000 // G1OffsetTableContigSpace code; copied from space.cpp.  Hope this can go
1001 // away eventually.
1002 
1003 void G1ContiguousSpace::clear(bool mangle_space) {
1004   set_top(bottom());
1005   _scan_top = bottom();
1006   CompactibleSpace::clear(mangle_space);
1007   reset_bot();
1008 }
1009 
1010 #ifndef PRODUCT
1011 void G1ContiguousSpace::mangle_unused_area() {
1012   mangle_unused_area_complete();
1013 }
1014 
1015 void G1ContiguousSpace::mangle_unused_area_complete() {
1016   SpaceMangler::mangle_region(MemRegion(top(), end()));
1017 }
1018 #endif
1019 
1020 void G1ContiguousSpace::print() const {
1021   print_short();
1022   tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
1023                 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
1024                 p2i(bottom()), p2i(top()), p2i(_bot_part.threshold()), p2i(end()));
1025 }
1026 
1027 HeapWord* G1ContiguousSpace::initialize_threshold() {
1028   return _bot_part.initialize_threshold();
1029 }
1030 
1031 HeapWord* G1ContiguousSpace::cross_threshold(HeapWord* start,
1032                                                     HeapWord* end) {
1033   _bot_part.alloc_block(start, end);
1034   return _bot_part.threshold();
1035 }
1036 
1037 HeapWord* G1ContiguousSpace::scan_top() const {
1038   G1CollectedHeap* g1h = G1CollectedHeap::heap();
1039   HeapWord* local_top = top();
1040   OrderAccess::loadload();
1041   const unsigned local_time_stamp = _gc_time_stamp;
1042   assert(local_time_stamp <= g1h->get_gc_time_stamp(), "invariant");
1043   if (local_time_stamp < g1h->get_gc_time_stamp()) {
1044     return local_top;
1045   } else {
1046     return _scan_top;
1047   }
1048 }
1049 
1050 void G1ContiguousSpace::record_timestamp() {
1051   G1CollectedHeap* g1h = G1CollectedHeap::heap();
1052   uint curr_gc_time_stamp = g1h->get_gc_time_stamp();
1053 
1054   if (_gc_time_stamp < curr_gc_time_stamp) {
1055     // Setting the time stamp here tells concurrent readers to look at
1056     // scan_top to know the maximum allowed address to look at.
1057 
1058     // scan_top should be bottom for all regions except for the
1059     // retained old alloc region which should have scan_top == top
1060     HeapWord* st = _scan_top;
1061     guarantee(st == _bottom || st == _top, "invariant");
1062 
1063     _gc_time_stamp = curr_gc_time_stamp;
1064   }
1065 }
1066 
1067 void G1ContiguousSpace::record_retained_region() {
1068   // scan_top is the maximum address where it's safe for the next gc to
1069   // scan this region.
1070   _scan_top = top();
1071 }
1072 
1073 void G1ContiguousSpace::safe_object_iterate(ObjectClosure* blk) {
1074   object_iterate(blk);
1075 }
1076 
1077 void G1ContiguousSpace::object_iterate(ObjectClosure* blk) {
1078   HeapWord* p = bottom();
1079   while (p < top()) {
1080     if (block_is_obj(p)) {
1081       blk->do_object(oop(p));
1082     }
1083     p += block_size(p);
1084   }
1085 }
1086 
1087 G1ContiguousSpace::G1ContiguousSpace(G1BlockOffsetTable* bot) :
1088   _bot_part(bot, this),
1089   _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
1090   _gc_time_stamp(0)
1091 {
1092 }
1093 
1094 void G1ContiguousSpace::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
1095   CompactibleSpace::initialize(mr, clear_space, mangle_space);
1096   _top = bottom();
1097   _scan_top = bottom();
1098   set_saved_mark_word(NULL);
1099   reset_bot();
1100 }
1101