1 /*
   2  * Copyright (c) 1997, 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 "classfile/javaClasses.hpp"
  27 #include "classfile/systemDictionary.hpp"
  28 #include "gc_implementation/shared/markSweep.inline.hpp"
  29 #include "gc_interface/collectedHeap.hpp"
  30 #include "gc_interface/collectedHeap.inline.hpp"
  31 #include "memory/genCollectedHeap.hpp"
  32 #include "memory/genOopClosures.inline.hpp"
  33 #include "oops/instanceRefKlass.hpp"
  34 #include "oops/oop.inline.hpp"
  35 #include "utilities/preserveException.hpp"
  36 #ifndef SERIALGC
  37 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
  38 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
  39 #include "gc_implementation/g1/g1RemSet.inline.hpp"
  40 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
  41 #include "gc_implementation/parNew/parOopClosures.inline.hpp"
  42 #include "gc_implementation/parallelScavenge/psPromotionManager.inline.hpp"
  43 #include "gc_implementation/parallelScavenge/psScavenge.inline.hpp"
  44 #include "oops/oop.pcgc.inline.hpp"
  45 #endif
  46 
  47 template <class T>
  48 static void specialized_oop_follow_contents(instanceRefKlass* ref, oop obj) {
  49   T* referent_addr = (T*)java_lang_ref_Reference::referent_addr(obj);
  50   T heap_oop = oopDesc::load_heap_oop(referent_addr);
  51   debug_only(
  52     if(TraceReferenceGC && PrintGCDetails) {
  53       gclog_or_tty->print_cr("instanceRefKlass::oop_follow_contents " INTPTR_FORMAT, obj);
  54     }
  55   )
  56   if (!oopDesc::is_null(heap_oop)) {
  57     oop referent = oopDesc::decode_heap_oop_not_null(heap_oop);
  58     if (!referent->is_gc_marked() &&
  59         MarkSweep::ref_processor()->discover_reference(obj, ref->reference_type())) {
  60       // reference was discovered, referent will be traversed later
  61       ref->instanceKlass::oop_follow_contents(obj);
  62       debug_only(
  63         if(TraceReferenceGC && PrintGCDetails) {
  64           gclog_or_tty->print_cr("       Non NULL enqueued " INTPTR_FORMAT, obj);
  65         }
  66       )
  67       return;
  68     } else {
  69       // treat referent as normal oop
  70       debug_only(
  71         if(TraceReferenceGC && PrintGCDetails) {
  72           gclog_or_tty->print_cr("       Non NULL normal " INTPTR_FORMAT, obj);
  73         }
  74       )
  75       MarkSweep::mark_and_push(referent_addr);
  76     }
  77   }
  78   T* next_addr = (T*)java_lang_ref_Reference::next_addr(obj);
  79   if (ReferenceProcessor::pending_list_uses_discovered_field()) {
  80     // Treat discovered as normal oop, if ref is not "active",
  81     // i.e. if next is non-NULL.
  82     T  next_oop = oopDesc::load_heap_oop(next_addr);
  83     if (!oopDesc::is_null(next_oop)) { // i.e. ref is not "active"
  84       T* discovered_addr = (T*)java_lang_ref_Reference::discovered_addr(obj);
  85       debug_only(
  86         if(TraceReferenceGC && PrintGCDetails) {
  87           gclog_or_tty->print_cr("   Process discovered as normal "
  88                                  INTPTR_FORMAT, discovered_addr);
  89         }
  90       )
  91       MarkSweep::mark_and_push(discovered_addr);
  92     }
  93   } else {
  94 #ifdef ASSERT
  95     // In the case of older JDKs which do not use the discoveredd
  96     // field for the pending list, an inactive ref (next != NULL)
  97     // must always have a NULL discovered field.
  98     oop next = oopDesc::load_decode_heap_oop(next_addr);
  99     oop discovered = java_lang_ref_Reference::discovered(obj);
 100     assert(oopDesc::is_null(next) || oopDesc::is_null(discovered),
 101            err_msg("Found an inactive reference " PTR_FORMAT " with a non-NULL discovered field",
 102                    obj));
 103 #endif
 104   }
 105   // treat next as normal oop.  next is a link in the reference queue.
 106   debug_only(
 107     if(TraceReferenceGC && PrintGCDetails) {
 108       gclog_or_tty->print_cr("   Process next as normal " INTPTR_FORMAT, next_addr);
 109     }
 110   )
 111   MarkSweep::mark_and_push(next_addr);
 112   ref->instanceKlass::oop_follow_contents(obj);
 113 }
 114 
 115 void instanceRefKlass::oop_follow_contents(oop obj) {
 116   if (UseCompressedOops) {
 117     specialized_oop_follow_contents<narrowOop>(this, obj);
 118   } else {
 119     specialized_oop_follow_contents<oop>(this, obj);
 120   }
 121 }
 122 
 123 #ifndef SERIALGC
 124 template <class T>
 125 void specialized_oop_follow_contents(instanceRefKlass* ref,
 126                                      ParCompactionManager* cm,
 127                                      oop obj) {
 128   T* referent_addr = (T*)java_lang_ref_Reference::referent_addr(obj);
 129   T heap_oop = oopDesc::load_heap_oop(referent_addr);
 130   debug_only(
 131     if(TraceReferenceGC && PrintGCDetails) {
 132       gclog_or_tty->print_cr("instanceRefKlass::oop_follow_contents " INTPTR_FORMAT, obj);
 133     }
 134   )
 135   if (!oopDesc::is_null(heap_oop)) {
 136     oop referent = oopDesc::decode_heap_oop_not_null(heap_oop);
 137     if (PSParallelCompact::mark_bitmap()->is_unmarked(referent) &&
 138         PSParallelCompact::ref_processor()->
 139           discover_reference(obj, ref->reference_type())) {
 140       // reference already enqueued, referent will be traversed later
 141       ref->instanceKlass::oop_follow_contents(cm, obj);
 142       debug_only(
 143         if(TraceReferenceGC && PrintGCDetails) {
 144           gclog_or_tty->print_cr("       Non NULL enqueued " INTPTR_FORMAT, obj);
 145         }
 146       )
 147       return;
 148     } else {
 149       // treat referent as normal oop
 150       debug_only(
 151         if(TraceReferenceGC && PrintGCDetails) {
 152           gclog_or_tty->print_cr("       Non NULL normal " INTPTR_FORMAT, obj);
 153         }
 154       )
 155       PSParallelCompact::mark_and_push(cm, referent_addr);
 156     }
 157   }
 158   T* next_addr = (T*)java_lang_ref_Reference::next_addr(obj);
 159   if (ReferenceProcessor::pending_list_uses_discovered_field()) {
 160     // Treat discovered as normal oop, if ref is not "active",
 161     // i.e. if next is non-NULL.
 162     T  next_oop = oopDesc::load_heap_oop(next_addr);
 163     if (!oopDesc::is_null(next_oop)) { // i.e. ref is not "active"
 164       T* discovered_addr = (T*)java_lang_ref_Reference::discovered_addr(obj);
 165       debug_only(
 166         if(TraceReferenceGC && PrintGCDetails) {
 167           gclog_or_tty->print_cr("   Process discovered as normal "
 168                                  INTPTR_FORMAT, discovered_addr);
 169         }
 170       )
 171       PSParallelCompact::mark_and_push(cm, discovered_addr);
 172     }
 173   } else {
 174 #ifdef ASSERT
 175     // In the case of older JDKs which do not use the discoveredd
 176     // field for the pending list, an inactive ref (next != NULL)
 177     // must always have a NULL discovered field.
 178     T next = oopDesc::load_heap_oop(next_addr);
 179     oop discovered = java_lang_ref_Reference::discovered(obj);
 180     assert(oopDesc::is_null(next) || oopDesc::is_null(discovered),
 181            err_msg("Found an inactive reference " PTR_FORMAT " with a non-NULL discovered field",
 182                    obj));
 183 #endif
 184   }
 185   PSParallelCompact::mark_and_push(cm, next_addr);
 186   ref->instanceKlass::oop_follow_contents(cm, obj);
 187 }
 188 
 189 void instanceRefKlass::oop_follow_contents(ParCompactionManager* cm,
 190                                            oop obj) {
 191   if (UseCompressedOops) {
 192     specialized_oop_follow_contents<narrowOop>(this, cm, obj);
 193   } else {
 194     specialized_oop_follow_contents<oop>(this, cm, obj);
 195   }
 196 }
 197 #endif // SERIALGC
 198 
 199 #ifdef ASSERT
 200 template <class T> void trace_reference_gc(const char *s, oop obj,
 201                                            T* referent_addr,
 202                                            T* next_addr,
 203                                            T* discovered_addr) {
 204   if(TraceReferenceGC && PrintGCDetails) {
 205     gclog_or_tty->print_cr("%s obj " INTPTR_FORMAT, s, (address)obj);
 206     gclog_or_tty->print_cr("     referent_addr/* " INTPTR_FORMAT " / "
 207          INTPTR_FORMAT, referent_addr,
 208          referent_addr ?
 209            (address)oopDesc::load_decode_heap_oop(referent_addr) : NULL);
 210     gclog_or_tty->print_cr("     next_addr/* " INTPTR_FORMAT " / "
 211          INTPTR_FORMAT, next_addr,
 212          next_addr ? (address)oopDesc::load_decode_heap_oop(next_addr) : NULL);
 213     gclog_or_tty->print_cr("     discovered_addr/* " INTPTR_FORMAT " / "
 214          INTPTR_FORMAT, discovered_addr,
 215          discovered_addr ?
 216            (address)oopDesc::load_decode_heap_oop(discovered_addr) : NULL);
 217   }
 218 }
 219 #endif
 220 
 221 template <class T> void specialized_oop_adjust_pointers(instanceRefKlass *ref, oop obj) {
 222   T* referent_addr = (T*)java_lang_ref_Reference::referent_addr(obj);
 223   MarkSweep::adjust_pointer(referent_addr);
 224   T* next_addr = (T*)java_lang_ref_Reference::next_addr(obj);
 225   MarkSweep::adjust_pointer(next_addr);
 226   T* discovered_addr = (T*)java_lang_ref_Reference::discovered_addr(obj);
 227   MarkSweep::adjust_pointer(discovered_addr);
 228   debug_only(trace_reference_gc("instanceRefKlass::oop_adjust_pointers", obj,
 229                                 referent_addr, next_addr, discovered_addr);)
 230 }
 231 
 232 int instanceRefKlass::oop_adjust_pointers(oop obj) {
 233   int size = size_helper();
 234   instanceKlass::oop_adjust_pointers(obj);
 235 
 236   if (UseCompressedOops) {
 237     specialized_oop_adjust_pointers<narrowOop>(this, obj);
 238   } else {
 239     specialized_oop_adjust_pointers<oop>(this, obj);
 240   }
 241   return size;
 242 }
 243 
 244 #define InstanceRefKlass_SPECIALIZED_OOP_ITERATE(T, nv_suffix, contains)        \
 245   T* disc_addr = (T*)java_lang_ref_Reference::discovered_addr(obj);             \
 246   if (closure->apply_to_weak_ref_discovered_field()) {                          \
 247     closure->do_oop##nv_suffix(disc_addr);                                      \
 248   }                                                                             \
 249                                                                                 \
 250   T* referent_addr = (T*)java_lang_ref_Reference::referent_addr(obj);           \
 251   T heap_oop = oopDesc::load_heap_oop(referent_addr);                           \
 252   ReferenceProcessor* rp = closure->_ref_processor;                             \
 253   if (!oopDesc::is_null(heap_oop)) {                                            \
 254     oop referent = oopDesc::decode_heap_oop_not_null(heap_oop);                 \
 255     if (!referent->is_gc_marked() && (rp != NULL) &&                            \
 256         rp->discover_reference(obj, reference_type())) {                        \
 257       return size;                                                              \
 258     } else if (contains(referent_addr)) {                                       \
 259       /* treat referent as normal oop */                                        \
 260       SpecializationStats::record_do_oop_call##nv_suffix(SpecializationStats::irk);\
 261       closure->do_oop##nv_suffix(referent_addr);                                \
 262     }                                                                           \
 263   }                                                                             \
 264   T* next_addr = (T*)java_lang_ref_Reference::next_addr(obj);                   \
 265   if (ReferenceProcessor::pending_list_uses_discovered_field()) {               \
 266     T next_oop  = oopDesc::load_heap_oop(next_addr);                            \
 267     /* Treat discovered as normal oop, if ref is not "active" (next non-NULL) */\
 268     if (!oopDesc::is_null(next_oop) && contains(disc_addr)) {                   \
 269         /* i.e. ref is not "active" */                                          \
 270       debug_only(                                                               \
 271         if(TraceReferenceGC && PrintGCDetails) {                                \
 272           gclog_or_tty->print_cr("   Process discovered as normal "             \
 273                                  INTPTR_FORMAT, disc_addr);                     \
 274         }                                                                       \
 275       )                                                                         \
 276       SpecializationStats::record_do_oop_call##nv_suffix(SpecializationStats::irk);\
 277       closure->do_oop##nv_suffix(disc_addr);                                    \
 278     }                                                                           \
 279   } else {                                                                      \
 280     /* In the case of older JDKs which do not use the discovered field for  */  \
 281     /* the pending list, an inactive ref (next != NULL) must always have a  */  \
 282     /* NULL discovered field. */                                                \
 283     debug_only(                                                                 \
 284       T next_oop = oopDesc::load_heap_oop(next_addr);                           \
 285       T disc_oop = oopDesc::load_heap_oop(disc_addr);                           \
 286       assert(oopDesc::is_null(next_oop) || oopDesc::is_null(disc_oop),          \
 287            err_msg("Found an inactive reference " PTR_FORMAT " with a non-NULL" \
 288                    "discovered field", obj));                                   \
 289     )                                                                           \
 290   }                                                                             \
 291   /* treat next as normal oop */                                                \
 292   if (contains(next_addr)) {                                                    \
 293     SpecializationStats::record_do_oop_call##nv_suffix(SpecializationStats::irk); \
 294     closure->do_oop##nv_suffix(next_addr);                                      \
 295   }                                                                             \
 296   return size;                                                                  \
 297 
 298 
 299 template <class T> bool contains(T *t) { return true; }
 300 
 301 // Macro to define instanceRefKlass::oop_oop_iterate for virtual/nonvirtual for
 302 // all closures.  Macros calling macros above for each oop size.
 303 
 304 #define InstanceRefKlass_OOP_OOP_ITERATE_DEFN(OopClosureType, nv_suffix)        \
 305                                                                                 \
 306 int instanceRefKlass::                                                          \
 307 oop_oop_iterate##nv_suffix(oop obj, OopClosureType* closure) {                  \
 308   /* Get size before changing pointers */                                       \
 309   SpecializationStats::record_iterate_call##nv_suffix(SpecializationStats::irk);\
 310                                                                                 \
 311   int size = instanceKlass::oop_oop_iterate##nv_suffix(obj, closure);           \
 312                                                                                 \
 313   if (UseCompressedOops) {                                                      \
 314     InstanceRefKlass_SPECIALIZED_OOP_ITERATE(narrowOop, nv_suffix, contains);   \
 315   } else {                                                                      \
 316     InstanceRefKlass_SPECIALIZED_OOP_ITERATE(oop, nv_suffix, contains);         \
 317   }                                                                             \
 318 }
 319 
 320 #ifndef SERIALGC
 321 #define InstanceRefKlass_OOP_OOP_ITERATE_BACKWARDS_DEFN(OopClosureType, nv_suffix) \
 322                                                                                 \
 323 int instanceRefKlass::                                                          \
 324 oop_oop_iterate_backwards##nv_suffix(oop obj, OopClosureType* closure) {        \
 325   /* Get size before changing pointers */                                       \
 326   SpecializationStats::record_iterate_call##nv_suffix(SpecializationStats::irk);\
 327                                                                                 \
 328   int size = instanceKlass::oop_oop_iterate_backwards##nv_suffix(obj, closure); \
 329                                                                                 \
 330   if (UseCompressedOops) {                                                      \
 331     InstanceRefKlass_SPECIALIZED_OOP_ITERATE(narrowOop, nv_suffix, contains);   \
 332   } else {                                                                      \
 333     InstanceRefKlass_SPECIALIZED_OOP_ITERATE(oop, nv_suffix, contains);         \
 334   }                                                                             \
 335 }
 336 #endif // !SERIALGC
 337 
 338 
 339 #define InstanceRefKlass_OOP_OOP_ITERATE_DEFN_m(OopClosureType, nv_suffix)      \
 340                                                                                 \
 341 int instanceRefKlass::                                                          \
 342 oop_oop_iterate##nv_suffix##_m(oop obj,                                         \
 343                                OopClosureType* closure,                         \
 344                                MemRegion mr) {                                  \
 345   SpecializationStats::record_iterate_call##nv_suffix(SpecializationStats::irk);\
 346                                                                                 \
 347   int size = instanceKlass::oop_oop_iterate##nv_suffix##_m(obj, closure, mr);   \
 348   if (UseCompressedOops) {                                                      \
 349     InstanceRefKlass_SPECIALIZED_OOP_ITERATE(narrowOop, nv_suffix, mr.contains); \
 350   } else {                                                                      \
 351     InstanceRefKlass_SPECIALIZED_OOP_ITERATE(oop, nv_suffix, mr.contains);      \
 352   }                                                                             \
 353 }
 354 
 355 ALL_OOP_OOP_ITERATE_CLOSURES_1(InstanceRefKlass_OOP_OOP_ITERATE_DEFN)
 356 ALL_OOP_OOP_ITERATE_CLOSURES_2(InstanceRefKlass_OOP_OOP_ITERATE_DEFN)
 357 #ifndef SERIALGC
 358 ALL_OOP_OOP_ITERATE_CLOSURES_1(InstanceRefKlass_OOP_OOP_ITERATE_BACKWARDS_DEFN)
 359 ALL_OOP_OOP_ITERATE_CLOSURES_2(InstanceRefKlass_OOP_OOP_ITERATE_BACKWARDS_DEFN)
 360 #endif // SERIALGC
 361 ALL_OOP_OOP_ITERATE_CLOSURES_1(InstanceRefKlass_OOP_OOP_ITERATE_DEFN_m)
 362 ALL_OOP_OOP_ITERATE_CLOSURES_2(InstanceRefKlass_OOP_OOP_ITERATE_DEFN_m)
 363 
 364 #ifndef SERIALGC
 365 template <class T>
 366 void specialized_oop_push_contents(instanceRefKlass *ref,
 367                                    PSPromotionManager* pm, oop obj) {
 368   T* referent_addr = (T*)java_lang_ref_Reference::referent_addr(obj);
 369   ReferenceProcessor* rp = PSScavenge::reference_processor();
 370   if (PSScavenge::should_scavenge(referent_addr)) {
 371     if (rp->discover_reference(obj, ref->reference_type())) {
 372       // reference already enqueued, referent and next will be traversed later
 373       ref->instanceKlass::oop_push_contents(pm, obj);
 374       return;
 375     } else {
 376       // treat referent as normal oop
 377       pm->claim_or_forward_depth(referent_addr);
 378     }
 379   }
 380   // Treat discovered as normal oop, if ref is not "active",
 381   // i.e. if next is non-NULL.
 382   T* next_addr = (T*)java_lang_ref_Reference::next_addr(obj);
 383   if (ReferenceProcessor::pending_list_uses_discovered_field()) {
 384     T  next_oop = oopDesc::load_heap_oop(next_addr);
 385     if (!oopDesc::is_null(next_oop)) { // i.e. ref is not "active"
 386       T* discovered_addr = (T*)java_lang_ref_Reference::discovered_addr(obj);
 387       debug_only(
 388         if(TraceReferenceGC && PrintGCDetails) {
 389           gclog_or_tty->print_cr("   Process discovered as normal "
 390                                  INTPTR_FORMAT, discovered_addr);
 391         }
 392       )
 393       if (PSScavenge::should_scavenge(discovered_addr)) {
 394         pm->claim_or_forward_depth(discovered_addr);
 395       }
 396     }
 397   } else {
 398 #ifdef ASSERT
 399     // In the case of older JDKs which do not use the discoveredd
 400     // field for the pending list, an inactive ref (next != NULL)
 401     // must always have a NULL discovered field.
 402     oop next = oopDesc::load_decode_heap_oop(next_addr);
 403     oop discovered = java_lang_ref_Reference::discovered(obj);
 404     assert(oopDesc::is_null(next) || oopDesc::is_null(discovered),
 405            err_msg("Found an inactive reference " PTR_FORMAT " with a non-NULL discovered field",
 406                    obj));
 407 #endif
 408   }
 409 
 410   // Treat next as normal oop;  next is a link in the reference queue.
 411   if (PSScavenge::should_scavenge(next_addr)) {
 412     pm->claim_or_forward_depth(next_addr);
 413   }
 414   ref->instanceKlass::oop_push_contents(pm, obj);
 415 }
 416 
 417 void instanceRefKlass::oop_push_contents(PSPromotionManager* pm, oop obj) {
 418   if (UseCompressedOops) {
 419     specialized_oop_push_contents<narrowOop>(this, pm, obj);
 420   } else {
 421     specialized_oop_push_contents<oop>(this, pm, obj);
 422   }
 423 }
 424 
 425 template <class T>
 426 void specialized_oop_update_pointers(instanceRefKlass *ref,
 427                                     ParCompactionManager* cm, oop obj) {
 428   T* referent_addr = (T*)java_lang_ref_Reference::referent_addr(obj);
 429   PSParallelCompact::adjust_pointer(referent_addr);
 430   T* next_addr = (T*)java_lang_ref_Reference::next_addr(obj);
 431   PSParallelCompact::adjust_pointer(next_addr);
 432   T* discovered_addr = (T*)java_lang_ref_Reference::discovered_addr(obj);
 433   PSParallelCompact::adjust_pointer(discovered_addr);
 434   debug_only(trace_reference_gc("instanceRefKlass::oop_update_ptrs", obj,
 435                                 referent_addr, next_addr, discovered_addr);)
 436 }
 437 
 438 int instanceRefKlass::oop_update_pointers(ParCompactionManager* cm, oop obj) {
 439   instanceKlass::oop_update_pointers(cm, obj);
 440   if (UseCompressedOops) {
 441     specialized_oop_update_pointers<narrowOop>(this, cm, obj);
 442   } else {
 443     specialized_oop_update_pointers<oop>(this, cm, obj);
 444   }
 445   return size_helper();
 446 }
 447 #endif // SERIALGC
 448 
 449 void instanceRefKlass::update_nonstatic_oop_maps(klassOop k) {
 450   // Clear the nonstatic oop-map entries corresponding to referent
 451   // and nextPending field.  They are treated specially by the
 452   // garbage collector.
 453   // The discovered field is used only by the garbage collector
 454   // and is also treated specially.
 455   instanceKlass* ik = instanceKlass::cast(k);
 456 
 457   // Check that we have the right class
 458   debug_only(static bool first_time = true);
 459   assert(k == SystemDictionary::Reference_klass() && first_time,
 460          "Invalid update of maps");
 461   debug_only(first_time = false);
 462   assert(ik->nonstatic_oop_map_count() == 1, "just checking");
 463 
 464   OopMapBlock* map = ik->start_of_nonstatic_oop_maps();
 465 
 466   // Check that the current map is (2,4) - currently points at field with
 467   // offset 2 (words) and has 4 map entries.
 468   debug_only(int offset = java_lang_ref_Reference::referent_offset);
 469   debug_only(unsigned int count = ((java_lang_ref_Reference::discovered_offset -
 470     java_lang_ref_Reference::referent_offset)/heapOopSize) + 1);
 471 
 472   if (UseSharedSpaces) {
 473     assert(map->offset() == java_lang_ref_Reference::queue_offset &&
 474            map->count() == 1, "just checking");
 475   } else {
 476     assert(map->offset() == offset && map->count() == count,
 477            "just checking");
 478 
 479     // Update map to (3,1) - point to offset of 3 (words) with 1 map entry.
 480     map->set_offset(java_lang_ref_Reference::queue_offset);
 481     map->set_count(1);
 482   }
 483 }
 484 
 485 
 486 // Verification
 487 
 488 void instanceRefKlass::oop_verify_on(oop obj, outputStream* st) {
 489   instanceKlass::oop_verify_on(obj, st);
 490   // Verify referent field
 491   oop referent = java_lang_ref_Reference::referent(obj);
 492 
 493   // We should make this general to all heaps
 494   GenCollectedHeap* gch = NULL;
 495   if (Universe::heap()->kind() == CollectedHeap::GenCollectedHeap)
 496     gch = GenCollectedHeap::heap();
 497 
 498   if (referent != NULL) {
 499     guarantee(referent->is_oop(), "referent field heap failed");
 500     if (gch != NULL && !gch->is_in_young(obj)) {
 501       // We do a specific remembered set check here since the referent
 502       // field is not part of the oop mask and therefore skipped by the
 503       // regular verify code.
 504       if (UseCompressedOops) {
 505         narrowOop* referent_addr = (narrowOop*)java_lang_ref_Reference::referent_addr(obj);
 506         obj->verify_old_oop(referent_addr, true);
 507       } else {
 508         oop* referent_addr = (oop*)java_lang_ref_Reference::referent_addr(obj);
 509         obj->verify_old_oop(referent_addr, true);
 510       }
 511     }
 512   }
 513   // Verify next field
 514   oop next = java_lang_ref_Reference::next(obj);
 515   if (next != NULL) {
 516     guarantee(next->is_oop(), "next field verify failed");
 517     guarantee(next->is_instanceRef(), "next field verify failed");
 518     if (gch != NULL && !gch->is_in_young(obj)) {
 519       // We do a specific remembered set check here since the next field is
 520       // not part of the oop mask and therefore skipped by the regular
 521       // verify code.
 522       if (UseCompressedOops) {
 523         narrowOop* next_addr = (narrowOop*)java_lang_ref_Reference::next_addr(obj);
 524         obj->verify_old_oop(next_addr, true);
 525       } else {
 526         oop* next_addr = (oop*)java_lang_ref_Reference::next_addr(obj);
 527         obj->verify_old_oop(next_addr, true);
 528       }
 529     }
 530   }
 531 }
 532 
 533 bool instanceRefKlass::owns_pending_list_lock(JavaThread* thread) {
 534   if (java_lang_ref_Reference::pending_list_lock() == NULL) return false;
 535   Handle h_lock(thread, java_lang_ref_Reference::pending_list_lock());
 536   return ObjectSynchronizer::current_thread_holds_lock(thread, h_lock);
 537 }
 538 
 539 void instanceRefKlass::acquire_pending_list_lock(BasicLock *pending_list_basic_lock) {
 540   // we may enter this with pending exception set
 541   PRESERVE_EXCEPTION_MARK;  // exceptions are never thrown, needed for TRAPS argument
 542   Handle h_lock(THREAD, java_lang_ref_Reference::pending_list_lock());
 543   ObjectSynchronizer::fast_enter(h_lock, pending_list_basic_lock, false, THREAD);
 544   assert(ObjectSynchronizer::current_thread_holds_lock(
 545            JavaThread::current(), h_lock),
 546          "Locking should have succeeded");
 547   if (HAS_PENDING_EXCEPTION) CLEAR_PENDING_EXCEPTION;
 548 }
 549 
 550 void instanceRefKlass::release_and_notify_pending_list_lock(
 551   BasicLock *pending_list_basic_lock) {
 552   // we may enter this with pending exception set
 553   PRESERVE_EXCEPTION_MARK;  // exceptions are never thrown, needed for TRAPS argument
 554   //
 555   Handle h_lock(THREAD, java_lang_ref_Reference::pending_list_lock());
 556   assert(ObjectSynchronizer::current_thread_holds_lock(
 557            JavaThread::current(), h_lock),
 558          "Lock should be held");
 559   // Notify waiters on pending lists lock if there is any reference.
 560   if (java_lang_ref_Reference::pending_list() != NULL) {
 561     ObjectSynchronizer::notifyall(h_lock, THREAD);
 562   }
 563   ObjectSynchronizer::fast_exit(h_lock(), pending_list_basic_lock, THREAD);
 564   if (HAS_PENDING_EXCEPTION) CLEAR_PENDING_EXCEPTION;
 565 }