1 /* 2 * Copyright (c) 2001, 2018, 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/systemDictionary.hpp" 27 #include "gc/shared/allocTracer.hpp" 28 #include "gc/shared/barrierSet.hpp" 29 #include "gc/shared/collectedHeap.hpp" 30 #include "gc/shared/collectedHeap.inline.hpp" 31 #include "gc/shared/gcLocker.inline.hpp" 32 #include "gc/shared/gcHeapSummary.hpp" 33 #include "gc/shared/gcTrace.hpp" 34 #include "gc/shared/gcTraceTime.inline.hpp" 35 #include "gc/shared/gcWhen.hpp" 36 #include "gc/shared/vmGCOperations.hpp" 37 #include "logging/log.hpp" 38 #include "memory/metaspace.hpp" 39 #include "memory/resourceArea.hpp" 40 #include "oops/instanceMirrorKlass.hpp" 41 #include "oops/oop.inline.hpp" 42 #include "runtime/handles.inline.hpp" 43 #include "runtime/init.hpp" 44 #include "runtime/thread.inline.hpp" 45 #include "runtime/threadSMR.hpp" 46 #include "runtime/vmThread.hpp" 47 #include "services/heapDumper.hpp" 48 #include "utilities/align.hpp" 49 50 class ClassLoaderData; 51 52 #ifdef ASSERT 53 int CollectedHeap::_fire_out_of_memory_count = 0; 54 #endif 55 56 size_t CollectedHeap::_filler_array_max_size = 0; 57 58 template <> 59 void EventLogBase<GCMessage>::print(outputStream* st, GCMessage& m) { 60 st->print_cr("GC heap %s", m.is_before ? "before" : "after"); 61 st->print_raw(m); 62 } 63 64 void GCHeapLog::log_heap(CollectedHeap* heap, bool before) { 65 if (!should_log()) { 66 return; 67 } 68 69 double timestamp = fetch_timestamp(); 70 MutexLockerEx ml(&_mutex, Mutex::_no_safepoint_check_flag); 71 int index = compute_log_index(); 72 _records[index].thread = NULL; // Its the GC thread so it's not that interesting. 73 _records[index].timestamp = timestamp; 74 _records[index].data.is_before = before; 75 stringStream st(_records[index].data.buffer(), _records[index].data.size()); 76 77 st.print_cr("{Heap %s GC invocations=%u (full %u):", 78 before ? "before" : "after", 79 heap->total_collections(), 80 heap->total_full_collections()); 81 82 heap->print_on(&st); 83 st.print_cr("}"); 84 } 85 86 VirtualSpaceSummary CollectedHeap::create_heap_space_summary() { 87 size_t capacity_in_words = capacity() / HeapWordSize; 88 89 return VirtualSpaceSummary( 90 reserved_region().start(), reserved_region().start() + capacity_in_words, reserved_region().end()); 91 } 92 93 GCHeapSummary CollectedHeap::create_heap_summary() { 94 VirtualSpaceSummary heap_space = create_heap_space_summary(); 95 return GCHeapSummary(heap_space, used()); 96 } 97 98 MetaspaceSummary CollectedHeap::create_metaspace_summary() { 99 const MetaspaceSizes meta_space( 100 MetaspaceUtils::committed_bytes(), 101 MetaspaceUtils::used_bytes(), 102 MetaspaceUtils::reserved_bytes()); 103 const MetaspaceSizes data_space( 104 MetaspaceUtils::committed_bytes(Metaspace::NonClassType), 105 MetaspaceUtils::used_bytes(Metaspace::NonClassType), 106 MetaspaceUtils::reserved_bytes(Metaspace::NonClassType)); 107 const MetaspaceSizes class_space( 108 MetaspaceUtils::committed_bytes(Metaspace::ClassType), 109 MetaspaceUtils::used_bytes(Metaspace::ClassType), 110 MetaspaceUtils::reserved_bytes(Metaspace::ClassType)); 111 112 const MetaspaceChunkFreeListSummary& ms_chunk_free_list_summary = 113 MetaspaceUtils::chunk_free_list_summary(Metaspace::NonClassType); 114 const MetaspaceChunkFreeListSummary& class_chunk_free_list_summary = 115 MetaspaceUtils::chunk_free_list_summary(Metaspace::ClassType); 116 117 return MetaspaceSummary(MetaspaceGC::capacity_until_GC(), meta_space, data_space, class_space, 118 ms_chunk_free_list_summary, class_chunk_free_list_summary); 119 } 120 121 void CollectedHeap::print_heap_before_gc() { 122 Universe::print_heap_before_gc(); 123 if (_gc_heap_log != NULL) { 124 _gc_heap_log->log_heap_before(this); 125 } 126 } 127 128 void CollectedHeap::print_heap_after_gc() { 129 Universe::print_heap_after_gc(); 130 if (_gc_heap_log != NULL) { 131 _gc_heap_log->log_heap_after(this); 132 } 133 } 134 135 void CollectedHeap::print_on_error(outputStream* st) const { 136 st->print_cr("Heap:"); 137 print_extended_on(st); 138 st->cr(); 139 140 BarrierSet::barrier_set()->print_on(st); 141 } 142 143 void CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 144 const GCHeapSummary& heap_summary = create_heap_summary(); 145 gc_tracer->report_gc_heap_summary(when, heap_summary); 146 147 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 148 gc_tracer->report_metaspace_summary(when, metaspace_summary); 149 } 150 151 void CollectedHeap::trace_heap_before_gc(const GCTracer* gc_tracer) { 152 trace_heap(GCWhen::BeforeGC, gc_tracer); 153 } 154 155 void CollectedHeap::trace_heap_after_gc(const GCTracer* gc_tracer) { 156 trace_heap(GCWhen::AfterGC, gc_tracer); 157 } 158 159 // WhiteBox API support for concurrent collectors. These are the 160 // default implementations, for collectors which don't support this 161 // feature. 162 bool CollectedHeap::supports_concurrent_phase_control() const { 163 return false; 164 } 165 166 const char* const* CollectedHeap::concurrent_phases() const { 167 static const char* const result[] = { NULL }; 168 return result; 169 } 170 171 bool CollectedHeap::request_concurrent_phase(const char* phase) { 172 return false; 173 } 174 175 // Memory state functions. 176 177 178 CollectedHeap::CollectedHeap() : 179 _is_gc_active(false), 180 _total_collections(0), 181 _total_full_collections(0), 182 _gc_cause(GCCause::_no_gc), 183 _gc_lastcause(GCCause::_no_gc) 184 { 185 const size_t max_len = size_t(arrayOopDesc::max_array_length(T_INT)); 186 const size_t elements_per_word = HeapWordSize / sizeof(jint); 187 _filler_array_max_size = align_object_size(filler_array_hdr_size() + 188 max_len / elements_per_word); 189 190 NOT_PRODUCT(_promotion_failure_alot_count = 0;) 191 NOT_PRODUCT(_promotion_failure_alot_gc_number = 0;) 192 193 if (UsePerfData) { 194 EXCEPTION_MARK; 195 196 // create the gc cause jvmstat counters 197 _perf_gc_cause = PerfDataManager::create_string_variable(SUN_GC, "cause", 198 80, GCCause::to_string(_gc_cause), CHECK); 199 200 _perf_gc_lastcause = 201 PerfDataManager::create_string_variable(SUN_GC, "lastCause", 202 80, GCCause::to_string(_gc_lastcause), CHECK); 203 } 204 205 // Create the ring log 206 if (LogEvents) { 207 _gc_heap_log = new GCHeapLog(); 208 } else { 209 _gc_heap_log = NULL; 210 } 211 } 212 213 // This interface assumes that it's being called by the 214 // vm thread. It collects the heap assuming that the 215 // heap lock is already held and that we are executing in 216 // the context of the vm thread. 217 void CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) { 218 assert(Thread::current()->is_VM_thread(), "Precondition#1"); 219 assert(Heap_lock->is_locked(), "Precondition#2"); 220 GCCauseSetter gcs(this, cause); 221 switch (cause) { 222 case GCCause::_heap_inspection: 223 case GCCause::_heap_dump: 224 case GCCause::_metadata_GC_threshold : { 225 HandleMark hm; 226 do_full_collection(false); // don't clear all soft refs 227 break; 228 } 229 case GCCause::_metadata_GC_clear_soft_refs: { 230 HandleMark hm; 231 do_full_collection(true); // do clear all soft refs 232 break; 233 } 234 default: 235 ShouldNotReachHere(); // Unexpected use of this function 236 } 237 } 238 239 MetaWord* CollectedHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, 240 size_t word_size, 241 Metaspace::MetadataType mdtype) { 242 uint loop_count = 0; 243 uint gc_count = 0; 244 uint full_gc_count = 0; 245 246 assert(!Heap_lock->owned_by_self(), "Should not be holding the Heap_lock"); 247 248 do { 249 MetaWord* result = loader_data->metaspace_non_null()->allocate(word_size, mdtype); 250 if (result != NULL) { 251 return result; 252 } 253 254 if (GCLocker::is_active_and_needs_gc()) { 255 // If the GCLocker is active, just expand and allocate. 256 // If that does not succeed, wait if this thread is not 257 // in a critical section itself. 258 result = loader_data->metaspace_non_null()->expand_and_allocate(word_size, mdtype); 259 if (result != NULL) { 260 return result; 261 } 262 JavaThread* jthr = JavaThread::current(); 263 if (!jthr->in_critical()) { 264 // Wait for JNI critical section to be exited 265 GCLocker::stall_until_clear(); 266 // The GC invoked by the last thread leaving the critical 267 // section will be a young collection and a full collection 268 // is (currently) needed for unloading classes so continue 269 // to the next iteration to get a full GC. 270 continue; 271 } else { 272 if (CheckJNICalls) { 273 fatal("Possible deadlock due to allocating while" 274 " in jni critical section"); 275 } 276 return NULL; 277 } 278 } 279 280 { // Need lock to get self consistent gc_count's 281 MutexLocker ml(Heap_lock); 282 gc_count = Universe::heap()->total_collections(); 283 full_gc_count = Universe::heap()->total_full_collections(); 284 } 285 286 // Generate a VM operation 287 VM_CollectForMetadataAllocation op(loader_data, 288 word_size, 289 mdtype, 290 gc_count, 291 full_gc_count, 292 GCCause::_metadata_GC_threshold); 293 VMThread::execute(&op); 294 295 // If GC was locked out, try again. Check before checking success because the 296 // prologue could have succeeded and the GC still have been locked out. 297 if (op.gc_locked()) { 298 continue; 299 } 300 301 if (op.prologue_succeeded()) { 302 return op.result(); 303 } 304 loop_count++; 305 if ((QueuedAllocationWarningCount > 0) && 306 (loop_count % QueuedAllocationWarningCount == 0)) { 307 log_warning(gc, ergo)("satisfy_failed_metadata_allocation() retries %d times," 308 " size=" SIZE_FORMAT, loop_count, word_size); 309 } 310 } while (true); // Until a GC is done 311 } 312 313 #ifndef PRODUCT 314 void CollectedHeap::check_for_bad_heap_word_value(HeapWord* addr, size_t size) { 315 if (CheckMemoryInitialization && ZapUnusedHeapArea) { 316 for (size_t slot = 0; slot < size; slot += 1) { 317 assert((*(intptr_t*) (addr + slot)) != ((intptr_t) badHeapWordVal), 318 "Found badHeapWordValue in post-allocation check"); 319 } 320 } 321 } 322 323 void CollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) { 324 if (CheckMemoryInitialization && ZapUnusedHeapArea) { 325 for (size_t slot = 0; slot < size; slot += 1) { 326 assert((*(intptr_t*) (addr + slot)) == ((intptr_t) badHeapWordVal), 327 "Found non badHeapWordValue in pre-allocation check"); 328 } 329 } 330 } 331 #endif // PRODUCT 332 333 #ifdef ASSERT 334 void CollectedHeap::check_for_valid_allocation_state() { 335 Thread *thread = Thread::current(); 336 // How to choose between a pending exception and a potential 337 // OutOfMemoryError? Don't allow pending exceptions. 338 // This is a VM policy failure, so how do we exhaustively test it? 339 assert(!thread->has_pending_exception(), 340 "shouldn't be allocating with pending exception"); 341 if (StrictSafepointChecks) { 342 assert(thread->allow_allocation(), 343 "Allocation done by thread for which allocation is blocked " 344 "by No_Allocation_Verifier!"); 345 // Allocation of an oop can always invoke a safepoint, 346 // hence, the true argument 347 thread->check_for_valid_safepoint_state(true); 348 } 349 } 350 #endif 351 352 HeapWord* CollectedHeap::allocate_from_tlab_slow(Klass* klass, Thread* thread, size_t size) { 353 354 // Retain tlab and allocate object in shared space if 355 // the amount free in the tlab is too large to discard. 356 if (thread->tlab().free() > thread->tlab().refill_waste_limit()) { 357 thread->tlab().record_slow_allocation(size); 358 return NULL; 359 } 360 361 // Discard tlab and allocate a new one. 362 // To minimize fragmentation, the last TLAB may be smaller than the rest. 363 size_t new_tlab_size = thread->tlab().compute_size(size); 364 365 thread->tlab().clear_before_allocation(); 366 367 if (new_tlab_size == 0) { 368 return NULL; 369 } 370 371 // Allocate a new TLAB... 372 HeapWord* obj = Universe::heap()->allocate_new_tlab(new_tlab_size); 373 if (obj == NULL) { 374 return NULL; 375 } 376 377 AllocTracer::send_allocation_in_new_tlab(klass, obj, new_tlab_size * HeapWordSize, size * HeapWordSize, thread); 378 379 if (ZeroTLAB) { 380 // ..and clear it. 381 Copy::zero_to_words(obj, new_tlab_size); 382 } else { 383 // ...and zap just allocated object. 384 #ifdef ASSERT 385 // Skip mangling the space corresponding to the object header to 386 // ensure that the returned space is not considered parsable by 387 // any concurrent GC thread. 388 size_t hdr_size = oopDesc::header_size(); 389 Copy::fill_to_words(obj + hdr_size, new_tlab_size - hdr_size, badHeapWordVal); 390 #endif // ASSERT 391 } 392 thread->tlab().fill(obj, obj + size, new_tlab_size); 393 return Universe::heap()->tlab_post_allocation_setup(obj); 394 } 395 396 size_t CollectedHeap::max_tlab_size() const { 397 // TLABs can't be bigger than we can fill with a int[Integer.MAX_VALUE]. 398 // This restriction could be removed by enabling filling with multiple arrays. 399 // If we compute that the reasonable way as 400 // header_size + ((sizeof(jint) * max_jint) / HeapWordSize) 401 // we'll overflow on the multiply, so we do the divide first. 402 // We actually lose a little by dividing first, 403 // but that just makes the TLAB somewhat smaller than the biggest array, 404 // which is fine, since we'll be able to fill that. 405 size_t max_int_size = typeArrayOopDesc::header_size(T_INT) + 406 sizeof(jint) * 407 ((juint) max_jint / (size_t) HeapWordSize); 408 return align_down(max_int_size, MinObjAlignment); 409 } 410 411 size_t CollectedHeap::filler_array_hdr_size() { 412 return align_object_offset(arrayOopDesc::header_size(T_INT)); // align to Long 413 } 414 415 size_t CollectedHeap::filler_array_min_size() { 416 return align_object_size(filler_array_hdr_size()); // align to MinObjAlignment 417 } 418 419 #ifdef ASSERT 420 void CollectedHeap::fill_args_check(HeapWord* start, size_t words) 421 { 422 assert(words >= min_fill_size(), "too small to fill"); 423 assert(is_object_aligned(words), "unaligned size"); 424 assert(Universe::heap()->is_in_reserved(start), "not in heap"); 425 assert(Universe::heap()->is_in_reserved(start + words - 1), "not in heap"); 426 } 427 428 void CollectedHeap::zap_filler_array(HeapWord* start, size_t words, bool zap) 429 { 430 if (ZapFillerObjects && zap) { 431 Copy::fill_to_words(start + filler_array_hdr_size(), 432 words - filler_array_hdr_size(), 0XDEAFBABE); 433 } 434 } 435 #endif // ASSERT 436 437 void 438 CollectedHeap::fill_with_array(HeapWord* start, size_t words, bool zap) 439 { 440 assert(words >= filler_array_min_size(), "too small for an array"); 441 assert(words <= filler_array_max_size(), "too big for a single object"); 442 443 const size_t payload_size = words - filler_array_hdr_size(); 444 const size_t len = payload_size * HeapWordSize / sizeof(jint); 445 assert((int)len >= 0, "size too large " SIZE_FORMAT " becomes %d", words, (int)len); 446 447 // Set the length first for concurrent GC. 448 ((arrayOop)start)->set_length((int)len); 449 post_allocation_setup_common(Universe::intArrayKlassObj(), start); 450 DEBUG_ONLY(zap_filler_array(start, words, zap);) 451 } 452 453 void 454 CollectedHeap::fill_with_object_impl(HeapWord* start, size_t words, bool zap) 455 { 456 assert(words <= filler_array_max_size(), "too big for a single object"); 457 458 if (words >= filler_array_min_size()) { 459 fill_with_array(start, words, zap); 460 } else if (words > 0) { 461 assert(words == min_fill_size(), "unaligned size"); 462 post_allocation_setup_common(SystemDictionary::Object_klass(), start); 463 } 464 } 465 466 void CollectedHeap::fill_with_object(HeapWord* start, size_t words, bool zap) 467 { 468 DEBUG_ONLY(fill_args_check(start, words);) 469 HandleMark hm; // Free handles before leaving. 470 fill_with_object_impl(start, words, zap); 471 } 472 473 void CollectedHeap::fill_with_objects(HeapWord* start, size_t words, bool zap) 474 { 475 DEBUG_ONLY(fill_args_check(start, words);) 476 HandleMark hm; // Free handles before leaving. 477 478 // Multiple objects may be required depending on the filler array maximum size. Fill 479 // the range up to that with objects that are filler_array_max_size sized. The 480 // remainder is filled with a single object. 481 const size_t min = min_fill_size(); 482 const size_t max = filler_array_max_size(); 483 while (words > max) { 484 const size_t cur = (words - max) >= min ? max : max - min; 485 fill_with_array(start, cur, zap); 486 start += cur; 487 words -= cur; 488 } 489 490 fill_with_object_impl(start, words, zap); 491 } 492 493 HeapWord* CollectedHeap::allocate_new_tlab(size_t size) { 494 guarantee(false, "thread-local allocation buffers not supported"); 495 return NULL; 496 } 497 498 void CollectedHeap::ensure_parsability(bool retire_tlabs) { 499 // The second disjunct in the assertion below makes a concession 500 // for the start-up verification done while the VM is being 501 // created. Callers be careful that you know that mutators 502 // aren't going to interfere -- for instance, this is permissible 503 // if we are still single-threaded and have either not yet 504 // started allocating (nothing much to verify) or we have 505 // started allocating but are now a full-fledged JavaThread 506 // (and have thus made our TLAB's) available for filling. 507 assert(SafepointSynchronize::is_at_safepoint() || 508 !is_init_completed(), 509 "Should only be called at a safepoint or at start-up" 510 " otherwise concurrent mutator activity may make heap " 511 " unparsable again"); 512 const bool use_tlab = UseTLAB; 513 // The main thread starts allocating via a TLAB even before it 514 // has added itself to the threads list at vm boot-up. 515 JavaThreadIteratorWithHandle jtiwh; 516 assert(!use_tlab || jtiwh.length() > 0, 517 "Attempt to fill tlabs before main thread has been added" 518 " to threads list is doomed to failure!"); 519 BarrierSet *bs = BarrierSet::barrier_set(); 520 for (; JavaThread *thread = jtiwh.next(); ) { 521 if (use_tlab) thread->tlab().make_parsable(retire_tlabs); 522 bs->make_parsable(thread); 523 } 524 } 525 526 void CollectedHeap::accumulate_statistics_all_tlabs() { 527 if (UseTLAB) { 528 assert(SafepointSynchronize::is_at_safepoint() || 529 !is_init_completed(), 530 "should only accumulate statistics on tlabs at safepoint"); 531 532 ThreadLocalAllocBuffer::accumulate_statistics_before_gc(); 533 } 534 } 535 536 void CollectedHeap::resize_all_tlabs() { 537 if (UseTLAB) { 538 assert(SafepointSynchronize::is_at_safepoint() || 539 !is_init_completed(), 540 "should only resize tlabs at safepoint"); 541 542 ThreadLocalAllocBuffer::resize_all_tlabs(); 543 } 544 } 545 546 void CollectedHeap::full_gc_dump(GCTimer* timer, bool before) { 547 assert(timer != NULL, "timer is null"); 548 if ((HeapDumpBeforeFullGC && before) || (HeapDumpAfterFullGC && !before)) { 549 GCTraceTime(Info, gc) tm(before ? "Heap Dump (before full gc)" : "Heap Dump (after full gc)", timer); 550 HeapDumper::dump_heap(); 551 } 552 553 LogTarget(Trace, gc, classhisto) lt; 554 if (lt.is_enabled()) { 555 GCTraceTime(Trace, gc, classhisto) tm(before ? "Class Histogram (before full gc)" : "Class Histogram (after full gc)", timer); 556 ResourceMark rm; 557 LogStream ls(lt); 558 VM_GC_HeapInspection inspector(&ls, false /* ! full gc */); 559 inspector.doit(); 560 } 561 } 562 563 void CollectedHeap::pre_full_gc_dump(GCTimer* timer) { 564 full_gc_dump(timer, true); 565 } 566 567 void CollectedHeap::post_full_gc_dump(GCTimer* timer) { 568 full_gc_dump(timer, false); 569 } 570 571 void CollectedHeap::initialize_reserved_region(HeapWord *start, HeapWord *end) { 572 // It is important to do this in a way such that concurrent readers can't 573 // temporarily think something is in the heap. (Seen this happen in asserts.) 574 _reserved.set_word_size(0); 575 _reserved.set_start(start); 576 _reserved.set_end(end); 577 } 578 579 void CollectedHeap::post_initialize() { 580 initialize_serviceability(); 581 } 582 583 #ifndef PRODUCT 584 585 bool CollectedHeap::promotion_should_fail(volatile size_t* count) { 586 // Access to count is not atomic; the value does not have to be exact. 587 if (PromotionFailureALot) { 588 const size_t gc_num = total_collections(); 589 const size_t elapsed_gcs = gc_num - _promotion_failure_alot_gc_number; 590 if (elapsed_gcs >= PromotionFailureALotInterval) { 591 // Test for unsigned arithmetic wrap-around. 592 if (++*count >= PromotionFailureALotCount) { 593 *count = 0; 594 return true; 595 } 596 } 597 } 598 return false; 599 } 600 601 bool CollectedHeap::promotion_should_fail() { 602 return promotion_should_fail(&_promotion_failure_alot_count); 603 } 604 605 void CollectedHeap::reset_promotion_should_fail(volatile size_t* count) { 606 if (PromotionFailureALot) { 607 _promotion_failure_alot_gc_number = total_collections(); 608 *count = 0; 609 } 610 } 611 612 void CollectedHeap::reset_promotion_should_fail() { 613 reset_promotion_should_fail(&_promotion_failure_alot_count); 614 } 615 616 #endif // #ifndef PRODUCT 617 618 bool CollectedHeap::supports_object_pinning() const { 619 return false; 620 } 621 622 oop CollectedHeap::pin_object(JavaThread* thread, oop obj) { 623 ShouldNotReachHere(); 624 return NULL; 625 } 626 627 void CollectedHeap::unpin_object(JavaThread* thread, oop obj) { 628 ShouldNotReachHere(); 629 } 630 631 HeapWord* CollectedHeap::tlab_post_allocation_setup(HeapWord* obj) { 632 return obj; 633 } 634 635 uint CollectedHeap::oop_extra_words() { 636 // Default implementation doesn't need extra space for oops. 637 return 0; 638 } 639 640 void CollectedHeap::accumulate_statistics_all_gclabs() { 641 // Default implementation does nothing. 642 } 643 644 #ifndef CC_INTERP 645 void CollectedHeap::compile_prepare_oop(MacroAssembler* masm, Register obj) { 646 // Default implementation does nothing. 647 } 648 #endif