1 /*
   2  * Copyright (c) 2001, 2011, 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 "gc_implementation/g1/g1BlockOffsetTable.inline.hpp"
  27 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
  28 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
  29 #include "gc_implementation/g1/heapRegion.inline.hpp"
  30 #include "gc_implementation/g1/heapRegionRemSet.hpp"
  31 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
  32 #include "memory/genOopClosures.inline.hpp"
  33 #include "memory/iterator.hpp"
  34 #include "oops/oop.inline.hpp"
  35 
  36 int HeapRegion::LogOfHRGrainBytes = 0;
  37 int HeapRegion::LogOfHRGrainWords = 0;
  38 int HeapRegion::GrainBytes        = 0;
  39 int HeapRegion::GrainWords        = 0;
  40 int HeapRegion::CardsPerRegion    = 0;
  41 
  42 HeapRegionDCTOC::HeapRegionDCTOC(G1CollectedHeap* g1,
  43                                  HeapRegion* hr, OopClosure* cl,
  44                                  CardTableModRefBS::PrecisionStyle precision,
  45                                  FilterKind fk) :
  46   ContiguousSpaceDCTOC(hr, cl, precision, NULL),
  47   _hr(hr), _fk(fk), _g1(g1)
  48 { }
  49 
  50 FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r,
  51                                                    OopClosure* oc) :
  52   _r_bottom(r->bottom()), _r_end(r->end()),
  53   _oc(oc), _out_of_region(0)
  54 {}
  55 
  56 class VerifyLiveClosure: public OopClosure {
  57 private:
  58   G1CollectedHeap* _g1h;
  59   CardTableModRefBS* _bs;
  60   oop _containing_obj;
  61   bool _failures;
  62   int _n_failures;
  63   VerifyOption _vo;
  64 public:
  65   // _vo == UsePrevMarking -> use "prev" marking information,
  66   // _vo == UseNextMarking -> use "next" marking information,
  67   // _vo == UseMarkWord    -> use mark word from object header.
  68   VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) :
  69     _g1h(g1h), _bs(NULL), _containing_obj(NULL),
  70     _failures(false), _n_failures(0), _vo(vo)
  71   {
  72     BarrierSet* bs = _g1h->barrier_set();
  73     if (bs->is_a(BarrierSet::CardTableModRef))
  74       _bs = (CardTableModRefBS*)bs;
  75   }
  76 
  77   void set_containing_obj(oop obj) {
  78     _containing_obj = obj;
  79   }
  80 
  81   bool failures() { return _failures; }
  82   int n_failures() { return _n_failures; }
  83 
  84   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
  85   virtual void do_oop(      oop* p) { do_oop_work(p); }
  86 
  87   void print_object(outputStream* out, oop obj) {
  88 #ifdef PRODUCT
  89     klassOop k = obj->klass();
  90     const char* class_name = instanceKlass::cast(k)->external_name();
  91     out->print_cr("class name %s", class_name);
  92 #else // PRODUCT
  93     obj->print_on(out);
  94 #endif // PRODUCT
  95   }
  96 
  97   template <class T> void do_oop_work(T* p) {
  98     assert(_containing_obj != NULL, "Precondition");
  99     assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
 100            "Precondition");
 101     T heap_oop = oopDesc::load_heap_oop(p);
 102     if (!oopDesc::is_null(heap_oop)) {
 103       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
 104       bool failed = false;
 105       if (!_g1h->is_in_closed_subset(obj) ||
 106           _g1h->is_obj_dead_cond(obj, _vo)) {
 107         if (!_failures) {
 108           gclog_or_tty->print_cr("");
 109           gclog_or_tty->print_cr("----------");
 110         }
 111         if (!_g1h->is_in_closed_subset(obj)) {
 112           HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
 113           gclog_or_tty->print_cr("Field "PTR_FORMAT
 114                                  " of live obj "PTR_FORMAT" in region "
 115                                  "["PTR_FORMAT", "PTR_FORMAT")",
 116                                  p, (void*) _containing_obj,
 117                                  from->bottom(), from->end());
 118           print_object(gclog_or_tty, _containing_obj);
 119           gclog_or_tty->print_cr("points to obj "PTR_FORMAT" not in the heap",
 120                                  (void*) obj);
 121         } else {
 122           HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
 123           HeapRegion* to   = _g1h->heap_region_containing((HeapWord*)obj);
 124           gclog_or_tty->print_cr("Field "PTR_FORMAT
 125                                  " of live obj "PTR_FORMAT" in region "
 126                                  "["PTR_FORMAT", "PTR_FORMAT")",
 127                                  p, (void*) _containing_obj,
 128                                  from->bottom(), from->end());
 129           print_object(gclog_or_tty, _containing_obj);
 130           gclog_or_tty->print_cr("points to dead obj "PTR_FORMAT" in region "
 131                                  "["PTR_FORMAT", "PTR_FORMAT")",
 132                                  (void*) obj, to->bottom(), to->end());
 133           print_object(gclog_or_tty, obj);
 134         }
 135         gclog_or_tty->print_cr("----------");
 136         _failures = true;
 137         failed = true;
 138         _n_failures++;
 139       }
 140 
 141       if (!_g1h->full_collection()) {
 142         HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
 143         HeapRegion* to   = _g1h->heap_region_containing(obj);
 144         if (from != NULL && to != NULL &&
 145             from != to &&
 146             !to->isHumongous()) {
 147           jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
 148           jbyte cv_field = *_bs->byte_for_const(p);
 149           const jbyte dirty = CardTableModRefBS::dirty_card_val();
 150 
 151           bool is_bad = !(from->is_young()
 152                           || to->rem_set()->contains_reference(p)
 153                           || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
 154                               (_containing_obj->is_objArray() ?
 155                                   cv_field == dirty
 156                                : cv_obj == dirty || cv_field == dirty));
 157           if (is_bad) {
 158             if (!_failures) {
 159               gclog_or_tty->print_cr("");
 160               gclog_or_tty->print_cr("----------");
 161             }
 162             gclog_or_tty->print_cr("Missing rem set entry:");
 163             gclog_or_tty->print_cr("Field "PTR_FORMAT" "
 164                                    "of obj "PTR_FORMAT", "
 165                                    "in region "HR_FORMAT,
 166                                    p, (void*) _containing_obj,
 167                                    HR_FORMAT_PARAMS(from));
 168             _containing_obj->print_on(gclog_or_tty);
 169             gclog_or_tty->print_cr("points to obj "PTR_FORMAT" "
 170                                    "in region "HR_FORMAT,
 171                                    (void*) obj,
 172                                    HR_FORMAT_PARAMS(to));
 173             obj->print_on(gclog_or_tty);
 174             gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",
 175                           cv_obj, cv_field);
 176             gclog_or_tty->print_cr("----------");
 177             _failures = true;
 178             if (!failed) _n_failures++;
 179           }
 180         }
 181       }
 182     }
 183   }
 184 };
 185 
 186 template<class ClosureType>
 187 HeapWord* walk_mem_region_loop(ClosureType* cl, G1CollectedHeap* g1h,
 188                                HeapRegion* hr,
 189                                HeapWord* cur, HeapWord* top) {
 190   oop cur_oop = oop(cur);
 191   int oop_size = cur_oop->size();
 192   HeapWord* next_obj = cur + oop_size;
 193   while (next_obj < top) {
 194     // Keep filtering the remembered set.
 195     if (!g1h->is_obj_dead(cur_oop, hr)) {
 196       // Bottom lies entirely below top, so we can call the
 197       // non-memRegion version of oop_iterate below.
 198       cur_oop->oop_iterate(cl);
 199     }
 200     cur = next_obj;
 201     cur_oop = oop(cur);
 202     oop_size = cur_oop->size();
 203     next_obj = cur + oop_size;
 204   }
 205   return cur;
 206 }
 207 
 208 void HeapRegionDCTOC::walk_mem_region_with_cl(MemRegion mr,
 209                                               HeapWord* bottom,
 210                                               HeapWord* top,
 211                                               OopClosure* cl) {
 212   G1CollectedHeap* g1h = _g1;
 213 
 214   int oop_size;
 215 
 216   OopClosure* cl2 = cl;
 217 
 218   // If we are scanning the remembered sets looking for refs
 219   // into the collection set during an evacuation pause then
 220   // we will want to 'discover' reference objects that point
 221   // to referents in the collection set.
 222   //
 223   // Unfortunately it is an instance of FilterIntoCSClosure
 224   // that is iterated over the reference fields of oops in
 225   // mr (and not the G1ParPushHeapRSClosure - which is the
 226   // cl parameter).
 227   // If we set the _ref_processor field in the FilterIntoCSClosure
 228   // instance, all the reference objects that are walked
 229   // (regardless of whether their referent object's are in
 230   // the cset) will be 'discovered'.
 231   //
 232   // The G1STWIsAlive closure considers a referent object that
 233   // is outside the cset as alive. The G1CopyingKeepAliveClosure
 234   // skips referents that are not in the cset.
 235   //
 236   // Therefore reference objects in mr with a referent that is
 237   // outside the cset should be OK.
 238 
 239   ReferenceProcessor* rp = _cl->_ref_processor;
 240   if (rp != NULL) {
 241     assert(rp == _g1->ref_processor_stw(), "should be stw");
 242     assert(_fk == IntoCSFilterKind, "should be looking for refs into CS");
 243   }
 244 
 245   FilterIntoCSClosure intoCSFilt(this, g1h, cl, rp);
 246   FilterOutOfRegionClosure outOfRegionFilt(_hr, cl);
 247 
 248   switch (_fk) {
 249   case IntoCSFilterKind:      cl2 = &intoCSFilt; break;
 250   case OutOfRegionFilterKind: cl2 = &outOfRegionFilt; break;
 251   }
 252 
 253   // Start filtering what we add to the remembered set. If the object is
 254   // not considered dead, either because it is marked (in the mark bitmap)
 255   // or it was allocated after marking finished, then we add it. Otherwise
 256   // we can safely ignore the object.
 257   if (!g1h->is_obj_dead(oop(bottom), _hr)) {
 258     oop_size = oop(bottom)->oop_iterate(cl2, mr);
 259   } else {
 260     oop_size = oop(bottom)->size();
 261   }
 262 
 263   bottom += oop_size;
 264 
 265   if (bottom < top) {
 266     // We replicate the loop below for several kinds of possible filters.
 267     switch (_fk) {
 268     case NoFilterKind:
 269       bottom = walk_mem_region_loop(cl, g1h, _hr, bottom, top);
 270       break;
 271 
 272     case IntoCSFilterKind: {
 273       FilterIntoCSClosure filt(this, g1h, cl, rp);
 274       bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
 275       break;
 276     }
 277 
 278     case OutOfRegionFilterKind: {
 279       FilterOutOfRegionClosure filt(_hr, cl);
 280       bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
 281       break;
 282     }
 283 
 284     default:
 285       ShouldNotReachHere();
 286     }
 287 
 288     // Last object. Need to do dead-obj filtering here too.
 289     if (!g1h->is_obj_dead(oop(bottom), _hr)) {
 290       oop(bottom)->oop_iterate(cl2, mr);
 291     }
 292   }
 293 }
 294 
 295 // Minimum region size; we won't go lower than that.
 296 // We might want to decrease this in the future, to deal with small
 297 // heaps a bit more efficiently.
 298 #define MIN_REGION_SIZE  (      1024 * 1024 )
 299 
 300 // Maximum region size; we don't go higher than that. There's a good
 301 // reason for having an upper bound. We don't want regions to get too
 302 // large, otherwise cleanup's effectiveness would decrease as there
 303 // will be fewer opportunities to find totally empty regions after
 304 // marking.
 305 #define MAX_REGION_SIZE  ( 32 * 1024 * 1024 )
 306 
 307 // The automatic region size calculation will try to have around this
 308 // many regions in the heap (based on the min heap size).
 309 #define TARGET_REGION_NUMBER          2048
 310 
 311 void HeapRegion::setup_heap_region_size(uintx min_heap_size) {
 312   // region_size in bytes
 313   uintx region_size = G1HeapRegionSize;
 314   if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {
 315     // We base the automatic calculation on the min heap size. This
 316     // can be problematic if the spread between min and max is quite
 317     // wide, imagine -Xms128m -Xmx32g. But, if we decided it based on
 318     // the max size, the region size might be way too large for the
 319     // min size. Either way, some users might have to set the region
 320     // size manually for some -Xms / -Xmx combos.
 321 
 322     region_size = MAX2(min_heap_size / TARGET_REGION_NUMBER,
 323                        (uintx) MIN_REGION_SIZE);
 324   }
 325 
 326   int region_size_log = log2_long((jlong) region_size);
 327   // Recalculate the region size to make sure it's a power of
 328   // 2. This means that region_size is the largest power of 2 that's
 329   // <= what we've calculated so far.
 330   region_size = ((uintx)1 << region_size_log);
 331 
 332   // Now make sure that we don't go over or under our limits.
 333   if (region_size < MIN_REGION_SIZE) {
 334     region_size = MIN_REGION_SIZE;
 335   } else if (region_size > MAX_REGION_SIZE) {
 336     region_size = MAX_REGION_SIZE;
 337   }
 338 
 339   // And recalculate the log.
 340   region_size_log = log2_long((jlong) region_size);
 341 
 342   // Now, set up the globals.
 343   guarantee(LogOfHRGrainBytes == 0, "we should only set it once");
 344   LogOfHRGrainBytes = region_size_log;
 345 
 346   guarantee(LogOfHRGrainWords == 0, "we should only set it once");
 347   LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize;
 348 
 349   guarantee(GrainBytes == 0, "we should only set it once");
 350   // The cast to int is safe, given that we've bounded region_size by
 351   // MIN_REGION_SIZE and MAX_REGION_SIZE.
 352   GrainBytes = (int) region_size;
 353 
 354   guarantee(GrainWords == 0, "we should only set it once");
 355   GrainWords = GrainBytes >> LogHeapWordSize;
 356   guarantee(1 << LogOfHRGrainWords == GrainWords, "sanity");
 357 
 358   guarantee(CardsPerRegion == 0, "we should only set it once");
 359   CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift;
 360 }
 361 
 362 void HeapRegion::reset_after_compaction() {
 363   G1OffsetTableContigSpace::reset_after_compaction();
 364   // After a compaction the mark bitmap is invalid, so we must
 365   // treat all objects as being inside the unmarked area.
 366   zero_marked_bytes();
 367   init_top_at_mark_start();
 368 }
 369 
 370 DirtyCardToOopClosure*
 371 HeapRegion::new_dcto_closure(OopClosure* cl,
 372                              CardTableModRefBS::PrecisionStyle precision,
 373                              HeapRegionDCTOC::FilterKind fk) {
 374   return new HeapRegionDCTOC(G1CollectedHeap::heap(),
 375                              this, cl, precision, fk);
 376 }
 377 
 378 void HeapRegion::hr_clear(bool par, bool clear_space) {
 379   assert(_humongous_type == NotHumongous,
 380          "we should have already filtered out humongous regions");
 381   assert(_humongous_start_region == NULL,
 382          "we should have already filtered out humongous regions");
 383   assert(_end == _orig_end,
 384          "we should have already filtered out humongous regions");
 385 
 386   _in_collection_set = false;
 387 
 388   set_young_index_in_cset(-1);
 389   uninstall_surv_rate_group();
 390   set_young_type(NotYoung);
 391   reset_pre_dummy_top();
 392 
 393   if (!par) {
 394     // If this is parallel, this will be done later.
 395     HeapRegionRemSet* hrrs = rem_set();
 396     if (hrrs != NULL) hrrs->clear();
 397     _claimed = InitialClaimValue;
 398   }
 399   zero_marked_bytes();
 400   set_sort_index(-1);
 401 
 402   _offsets.resize(HeapRegion::GrainWords);
 403   init_top_at_mark_start();
 404   if (clear_space) clear(SpaceDecorator::Mangle);
 405 }
 406 
 407 void HeapRegion::par_clear() {
 408   assert(used() == 0, "the region should have been already cleared");
 409   assert(capacity() == (size_t) HeapRegion::GrainBytes,
 410          "should be back to normal");
 411   HeapRegionRemSet* hrrs = rem_set();
 412   hrrs->clear();
 413   CardTableModRefBS* ct_bs =
 414                    (CardTableModRefBS*)G1CollectedHeap::heap()->barrier_set();
 415   ct_bs->clear(MemRegion(bottom(), end()));
 416 }
 417 
 418 // <PREDICTION>
 419 void HeapRegion::calc_gc_efficiency() {
 420   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 421   _gc_efficiency = (double) garbage_bytes() /
 422                             g1h->predict_region_elapsed_time_ms(this, false);
 423 }
 424 // </PREDICTION>
 425 
 426 void HeapRegion::set_startsHumongous(HeapWord* new_top, HeapWord* new_end) {
 427   assert(!isHumongous(), "sanity / pre-condition");
 428   assert(end() == _orig_end,
 429          "Should be normal before the humongous object allocation");
 430   assert(top() == bottom(), "should be empty");
 431   assert(bottom() <= new_top && new_top <= new_end, "pre-condition");
 432 
 433   _humongous_type = StartsHumongous;
 434   _humongous_start_region = this;
 435 
 436   set_end(new_end);
 437   _offsets.set_for_starts_humongous(new_top);
 438 }
 439 
 440 void HeapRegion::set_continuesHumongous(HeapRegion* first_hr) {
 441   assert(!isHumongous(), "sanity / pre-condition");
 442   assert(end() == _orig_end,
 443          "Should be normal before the humongous object allocation");
 444   assert(top() == bottom(), "should be empty");
 445   assert(first_hr->startsHumongous(), "pre-condition");
 446 
 447   _humongous_type = ContinuesHumongous;
 448   _humongous_start_region = first_hr;
 449 }
 450 
 451 void HeapRegion::set_notHumongous() {
 452   assert(isHumongous(), "pre-condition");
 453 
 454   if (startsHumongous()) {
 455     assert(top() <= end(), "pre-condition");
 456     set_end(_orig_end);
 457     if (top() > end()) {
 458       // at least one "continues humongous" region after it
 459       set_top(end());
 460     }
 461   } else {
 462     // continues humongous
 463     assert(end() == _orig_end, "sanity");
 464   }
 465 
 466   assert(capacity() == (size_t) HeapRegion::GrainBytes, "pre-condition");
 467   _humongous_type = NotHumongous;
 468   _humongous_start_region = NULL;
 469 }
 470 
 471 bool HeapRegion::claimHeapRegion(jint claimValue) {
 472   jint current = _claimed;
 473   if (current != claimValue) {
 474     jint res = Atomic::cmpxchg(claimValue, &_claimed, current);
 475     if (res == current) {
 476       return true;
 477     }
 478   }
 479   return false;
 480 }
 481 
 482 HeapWord* HeapRegion::next_block_start_careful(HeapWord* addr) {
 483   HeapWord* low = addr;
 484   HeapWord* high = end();
 485   while (low < high) {
 486     size_t diff = pointer_delta(high, low);
 487     // Must add one below to bias toward the high amount.  Otherwise, if
 488   // "high" were at the desired value, and "low" were one less, we
 489     // would not converge on "high".  This is not symmetric, because
 490     // we set "high" to a block start, which might be the right one,
 491     // which we don't do for "low".
 492     HeapWord* middle = low + (diff+1)/2;
 493     if (middle == high) return high;
 494     HeapWord* mid_bs = block_start_careful(middle);
 495     if (mid_bs < addr) {
 496       low = middle;
 497     } else {
 498       high = mid_bs;
 499     }
 500   }
 501   assert(low == high && low >= addr, "Didn't work.");
 502   return low;
 503 }
 504 
 505 void HeapRegion::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
 506   G1OffsetTableContigSpace::initialize(mr, false, mangle_space);
 507   hr_clear(false/*par*/, clear_space);
 508 }
 509 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
 510 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
 511 #endif // _MSC_VER
 512 
 513 
 514 HeapRegion::
 515 HeapRegion(size_t hrs_index, G1BlockOffsetSharedArray* sharedOffsetArray,
 516            MemRegion mr, bool is_zeroed)
 517   : G1OffsetTableContigSpace(sharedOffsetArray, mr, is_zeroed),
 518     _hrs_index(hrs_index),
 519     _humongous_type(NotHumongous), _humongous_start_region(NULL),
 520     _in_collection_set(false),
 521     _next_in_special_set(NULL), _orig_end(NULL),
 522     _claimed(InitialClaimValue), _evacuation_failed(false),
 523     _prev_marked_bytes(0), _next_marked_bytes(0), _sort_index(-1),
 524     _gc_efficiency(0.0),
 525     _young_type(NotYoung), _next_young_region(NULL),
 526     _next_dirty_cards_region(NULL), _next(NULL), _pending_removal(false),
 527 #ifdef ASSERT
 528     _containing_set(NULL),
 529 #endif // ASSERT
 530      _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),
 531     _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),
 532     _predicted_bytes_to_copy(0)
 533 {
 534   _orig_end = mr.end();
 535   // Note that initialize() will set the start of the unmarked area of the
 536   // region.
 537   this->initialize(mr, !is_zeroed, SpaceDecorator::Mangle);
 538   set_top(bottom());
 539   set_saved_mark();
 540 
 541   _rem_set =  new HeapRegionRemSet(sharedOffsetArray, this);
 542 
 543   assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
 544   // In case the region is allocated during a pause, note the top.
 545   // We haven't done any counting on a brand new region.
 546   _top_at_conc_mark_count = bottom();
 547 }
 548 
 549 class NextCompactionHeapRegionClosure: public HeapRegionClosure {
 550   const HeapRegion* _target;
 551   bool _target_seen;
 552   HeapRegion* _last;
 553   CompactibleSpace* _res;
 554 public:
 555   NextCompactionHeapRegionClosure(const HeapRegion* target) :
 556     _target(target), _target_seen(false), _res(NULL) {}
 557   bool doHeapRegion(HeapRegion* cur) {
 558     if (_target_seen) {
 559       if (!cur->isHumongous()) {
 560         _res = cur;
 561         return true;
 562       }
 563     } else if (cur == _target) {
 564       _target_seen = true;
 565     }
 566     return false;
 567   }
 568   CompactibleSpace* result() { return _res; }
 569 };
 570 
 571 CompactibleSpace* HeapRegion::next_compaction_space() const {
 572   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 573   // cast away const-ness
 574   HeapRegion* r = (HeapRegion*) this;
 575   NextCompactionHeapRegionClosure blk(r);
 576   g1h->heap_region_iterate_from(r, &blk);
 577   return blk.result();
 578 }
 579 
 580 void HeapRegion::save_marks() {
 581   set_saved_mark();
 582 }
 583 
 584 void HeapRegion::oops_in_mr_iterate(MemRegion mr, OopClosure* cl) {
 585   HeapWord* p = mr.start();
 586   HeapWord* e = mr.end();
 587   oop obj;
 588   while (p < e) {
 589     obj = oop(p);
 590     p += obj->oop_iterate(cl);
 591   }
 592   assert(p == e, "bad memregion: doesn't end on obj boundary");
 593 }
 594 
 595 #define HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
 596 void HeapRegion::oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \
 597   ContiguousSpace::oop_since_save_marks_iterate##nv_suffix(cl);              \
 598 }
 599 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN)
 600 
 601 
 602 void HeapRegion::oop_before_save_marks_iterate(OopClosure* cl) {
 603   oops_in_mr_iterate(MemRegion(bottom(), saved_mark_word()), cl);
 604 }
 605 
 606 HeapWord*
 607 HeapRegion::object_iterate_mem_careful(MemRegion mr,
 608                                                  ObjectClosure* cl) {
 609   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 610   // We used to use "block_start_careful" here.  But we're actually happy
 611   // to update the BOT while we do this...
 612   HeapWord* cur = block_start(mr.start());
 613   mr = mr.intersection(used_region());
 614   if (mr.is_empty()) return NULL;
 615   // Otherwise, find the obj that extends onto mr.start().
 616 
 617   assert(cur <= mr.start()
 618          && (oop(cur)->klass_or_null() == NULL ||
 619              cur + oop(cur)->size() > mr.start()),
 620          "postcondition of block_start");
 621   oop obj;
 622   while (cur < mr.end()) {
 623     obj = oop(cur);
 624     if (obj->klass_or_null() == NULL) {
 625       // Ran into an unparseable point.
 626       return cur;
 627     } else if (!g1h->is_obj_dead(obj)) {
 628       cl->do_object(obj);
 629     }
 630     if (cl->abort()) return cur;
 631     // The check above must occur before the operation below, since an
 632     // abort might invalidate the "size" operation.
 633     cur += obj->size();
 634   }
 635   return NULL;
 636 }
 637 
 638 HeapWord*
 639 HeapRegion::
 640 oops_on_card_seq_iterate_careful(MemRegion mr,
 641                                  FilterOutOfRegionClosure* cl,
 642                                  bool filter_young,
 643                                  jbyte* card_ptr) {
 644   // Currently, we should only have to clean the card if filter_young
 645   // is true and vice versa.
 646   if (filter_young) {
 647     assert(card_ptr != NULL, "pre-condition");
 648   } else {
 649     assert(card_ptr == NULL, "pre-condition");
 650   }
 651   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 652 
 653   // If we're within a stop-world GC, then we might look at a card in a
 654   // GC alloc region that extends onto a GC LAB, which may not be
 655   // parseable.  Stop such at the "saved_mark" of the region.
 656   if (G1CollectedHeap::heap()->is_gc_active()) {
 657     mr = mr.intersection(used_region_at_save_marks());
 658   } else {
 659     mr = mr.intersection(used_region());
 660   }
 661   if (mr.is_empty()) return NULL;
 662   // Otherwise, find the obj that extends onto mr.start().
 663 
 664   // The intersection of the incoming mr (for the card) and the
 665   // allocated part of the region is non-empty. This implies that
 666   // we have actually allocated into this region. The code in
 667   // G1CollectedHeap.cpp that allocates a new region sets the
 668   // is_young tag on the region before allocating. Thus we
 669   // safely know if this region is young.
 670   if (is_young() && filter_young) {
 671     return NULL;
 672   }
 673 
 674   assert(!is_young(), "check value of filter_young");
 675 
 676   // We can only clean the card here, after we make the decision that
 677   // the card is not young. And we only clean the card if we have been
 678   // asked to (i.e., card_ptr != NULL).
 679   if (card_ptr != NULL) {
 680     *card_ptr = CardTableModRefBS::clean_card_val();
 681     // We must complete this write before we do any of the reads below.
 682     OrderAccess::storeload();
 683   }
 684 
 685   // We used to use "block_start_careful" here.  But we're actually happy
 686   // to update the BOT while we do this...
 687   HeapWord* cur = block_start(mr.start());
 688   assert(cur <= mr.start(), "Postcondition");
 689 
 690   while (cur <= mr.start()) {
 691     if (oop(cur)->klass_or_null() == NULL) {
 692       // Ran into an unparseable point.
 693       return cur;
 694     }
 695     // Otherwise...
 696     int sz = oop(cur)->size();
 697     if (cur + sz > mr.start()) break;
 698     // Otherwise, go on.
 699     cur = cur + sz;
 700   }
 701   oop obj;
 702   obj = oop(cur);
 703   // If we finish this loop...
 704   assert(cur <= mr.start()
 705          && obj->klass_or_null() != NULL
 706          && cur + obj->size() > mr.start(),
 707          "Loop postcondition");
 708   if (!g1h->is_obj_dead(obj)) {
 709     obj->oop_iterate(cl, mr);
 710   }
 711 
 712   HeapWord* next;
 713   while (cur < mr.end()) {
 714     obj = oop(cur);
 715     if (obj->klass_or_null() == NULL) {
 716       // Ran into an unparseable point.
 717       return cur;
 718     };
 719     // Otherwise:
 720     next = (cur + obj->size());
 721     if (!g1h->is_obj_dead(obj)) {
 722       if (next < mr.end()) {
 723         obj->oop_iterate(cl);
 724       } else {
 725         // this obj spans the boundary.  If it's an array, stop at the
 726         // boundary.
 727         if (obj->is_objArray()) {
 728           obj->oop_iterate(cl, mr);
 729         } else {
 730           obj->oop_iterate(cl);
 731         }
 732       }
 733     }
 734     cur = next;
 735   }
 736   return NULL;
 737 }
 738 
 739 void HeapRegion::print() const { print_on(gclog_or_tty); }
 740 void HeapRegion::print_on(outputStream* st) const {
 741   if (isHumongous()) {
 742     if (startsHumongous())
 743       st->print(" HS");
 744     else
 745       st->print(" HC");
 746   } else {
 747     st->print("   ");
 748   }
 749   if (in_collection_set())
 750     st->print(" CS");
 751   else
 752     st->print("   ");
 753   if (is_young())
 754     st->print(is_survivor() ? " SU" : " Y ");
 755   else
 756     st->print("   ");
 757   if (is_empty())
 758     st->print(" F");
 759   else
 760     st->print("  ");
 761   st->print(" %5d", _gc_time_stamp);
 762   st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT,
 763             prev_top_at_mark_start(), next_top_at_mark_start());
 764   G1OffsetTableContigSpace::print_on(st);
 765 }
 766 
 767 void HeapRegion::verify(bool allow_dirty) const {
 768   bool dummy = false;
 769   verify(allow_dirty, VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
 770 }
 771 
 772 // This really ought to be commoned up into OffsetTableContigSpace somehow.
 773 // We would need a mechanism to make that code skip dead objects.
 774 
 775 void HeapRegion::verify(bool allow_dirty,
 776                         VerifyOption vo,
 777                         bool* failures) const {
 778   G1CollectedHeap* g1 = G1CollectedHeap::heap();
 779   *failures = false;
 780   HeapWord* p = bottom();
 781   HeapWord* prev_p = NULL;
 782   VerifyLiveClosure vl_cl(g1, vo);
 783   bool is_humongous = isHumongous();
 784   bool do_bot_verify = !is_young();
 785   size_t object_num = 0;
 786   while (p < top()) {
 787     oop obj = oop(p);
 788     size_t obj_size = obj->size();
 789     object_num += 1;
 790 
 791     if (is_humongous != g1->isHumongous(obj_size)) {
 792       gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size ("
 793                              SIZE_FORMAT" words) in a %shumongous region",
 794                              p, g1->isHumongous(obj_size) ? "" : "non-",
 795                              obj_size, is_humongous ? "" : "non-");
 796        *failures = true;
 797        return;
 798     }
 799 
 800     // If it returns false, verify_for_object() will output the
 801     // appropriate messasge.
 802     if (do_bot_verify && !_offsets.verify_for_object(p, obj_size)) {
 803       *failures = true;
 804       return;
 805     }
 806 
 807     if (!g1->is_obj_dead_cond(obj, this, vo)) {
 808       if (obj->is_oop()) {
 809         klassOop klass = obj->klass();
 810         if (!klass->is_perm()) {
 811           gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
 812                                  "not in perm", klass, obj);
 813           *failures = true;
 814           return;
 815         } else if (!klass->is_klass()) {
 816           gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
 817                                  "not a klass", klass, obj);
 818           *failures = true;
 819           return;
 820         } else {
 821           vl_cl.set_containing_obj(obj);
 822           obj->oop_iterate(&vl_cl);
 823           if (vl_cl.failures()) {
 824             *failures = true;
 825           }
 826           if (G1MaxVerifyFailures >= 0 &&
 827               vl_cl.n_failures() >= G1MaxVerifyFailures) {
 828             return;
 829           }
 830         }
 831       } else {
 832         gclog_or_tty->print_cr(PTR_FORMAT" no an oop", obj);
 833         *failures = true;
 834         return;
 835       }
 836     }
 837     prev_p = p;
 838     p += obj_size;
 839   }
 840 
 841   if (p != top()) {
 842     gclog_or_tty->print_cr("end of last object "PTR_FORMAT" "
 843                            "does not match top "PTR_FORMAT, p, top());
 844     *failures = true;
 845     return;
 846   }
 847 
 848   HeapWord* the_end = end();
 849   assert(p == top(), "it should still hold");
 850   // Do some extra BOT consistency checking for addresses in the
 851   // range [top, end). BOT look-ups in this range should yield
 852   // top. No point in doing that if top == end (there's nothing there).
 853   if (p < the_end) {
 854     // Look up top
 855     HeapWord* addr_1 = p;
 856     HeapWord* b_start_1 = _offsets.block_start_const(addr_1);
 857     if (b_start_1 != p) {
 858       gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" "
 859                              " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
 860                              addr_1, b_start_1, p);
 861       *failures = true;
 862       return;
 863     }
 864 
 865     // Look up top + 1
 866     HeapWord* addr_2 = p + 1;
 867     if (addr_2 < the_end) {
 868       HeapWord* b_start_2 = _offsets.block_start_const(addr_2);
 869       if (b_start_2 != p) {
 870         gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" "
 871                                " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
 872                                addr_2, b_start_2, p);
 873         *failures = true;
 874         return;
 875       }
 876     }
 877 
 878     // Look up an address between top and end
 879     size_t diff = pointer_delta(the_end, p) / 2;
 880     HeapWord* addr_3 = p + diff;
 881     if (addr_3 < the_end) {
 882       HeapWord* b_start_3 = _offsets.block_start_const(addr_3);
 883       if (b_start_3 != p) {
 884         gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" "
 885                                " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
 886                                addr_3, b_start_3, p);
 887         *failures = true;
 888         return;
 889       }
 890     }
 891 
 892     // Loook up end - 1
 893     HeapWord* addr_4 = the_end - 1;
 894     HeapWord* b_start_4 = _offsets.block_start_const(addr_4);
 895     if (b_start_4 != p) {
 896       gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" "
 897                              " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
 898                              addr_4, b_start_4, p);
 899       *failures = true;
 900       return;
 901     }
 902   }
 903 
 904   if (is_humongous && object_num > 1) {
 905     gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
 906                            "but has "SIZE_FORMAT", objects",
 907                            bottom(), end(), object_num);
 908     *failures = true;
 909     return;
 910   }
 911 }
 912 
 913 // G1OffsetTableContigSpace code; copied from space.cpp.  Hope this can go
 914 // away eventually.
 915 
 916 void G1OffsetTableContigSpace::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
 917   // false ==> we'll do the clearing if there's clearing to be done.
 918   ContiguousSpace::initialize(mr, false, mangle_space);
 919   _offsets.zero_bottom_entry();
 920   _offsets.initialize_threshold();
 921   if (clear_space) clear(mangle_space);
 922 }
 923 
 924 void G1OffsetTableContigSpace::clear(bool mangle_space) {
 925   ContiguousSpace::clear(mangle_space);
 926   _offsets.zero_bottom_entry();
 927   _offsets.initialize_threshold();
 928 }
 929 
 930 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
 931   Space::set_bottom(new_bottom);
 932   _offsets.set_bottom(new_bottom);
 933 }
 934 
 935 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {
 936   Space::set_end(new_end);
 937   _offsets.resize(new_end - bottom());
 938 }
 939 
 940 void G1OffsetTableContigSpace::print() const {
 941   print_short();
 942   gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
 943                 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
 944                 bottom(), top(), _offsets.threshold(), end());
 945 }
 946 
 947 HeapWord* G1OffsetTableContigSpace::initialize_threshold() {
 948   return _offsets.initialize_threshold();
 949 }
 950 
 951 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start,
 952                                                     HeapWord* end) {
 953   _offsets.alloc_block(start, end);
 954   return _offsets.threshold();
 955 }
 956 
 957 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const {
 958   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 959   assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" );
 960   if (_gc_time_stamp < g1h->get_gc_time_stamp())
 961     return top();
 962   else
 963     return ContiguousSpace::saved_mark_word();
 964 }
 965 
 966 void G1OffsetTableContigSpace::set_saved_mark() {
 967   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 968   unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();
 969 
 970   if (_gc_time_stamp < curr_gc_time_stamp) {
 971     // The order of these is important, as another thread might be
 972     // about to start scanning this region. If it does so after
 973     // set_saved_mark and before _gc_time_stamp = ..., then the latter
 974     // will be false, and it will pick up top() as the high water mark
 975     // of region. If it does so after _gc_time_stamp = ..., then it
 976     // will pick up the right saved_mark_word() as the high water mark
 977     // of the region. Either way, the behaviour will be correct.
 978     ContiguousSpace::set_saved_mark();
 979     OrderAccess::storestore();
 980     _gc_time_stamp = curr_gc_time_stamp;
 981     // No need to do another barrier to flush the writes above. If
 982     // this is called in parallel with other threads trying to
 983     // allocate into the region, the caller should call this while
 984     // holding a lock and when the lock is released the writes will be
 985     // flushed.
 986   }
 987 }
 988 
 989 G1OffsetTableContigSpace::
 990 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
 991                          MemRegion mr, bool is_zeroed) :
 992   _offsets(sharedOffsetArray, mr),
 993   _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
 994   _gc_time_stamp(0)
 995 {
 996   _offsets.set_space(this);
 997   initialize(mr, !is_zeroed, SpaceDecorator::Mangle);
 998 }