--- a/src/hotspot/share/gc/shared/cardTableModRefBS.cpp Thu Mar 29 17:52:32 2018 +0530
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,189 +0,0 @@
-/*
- * Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- *
- */
-
-#include "precompiled.hpp"
-#include "gc/shared/cardTableModRefBS.inline.hpp"
-#include "gc/shared/collectedHeap.hpp"
-#include "gc/shared/genCollectedHeap.hpp"
-#include "gc/shared/space.inline.hpp"
-#include "logging/log.hpp"
-#include "memory/virtualspace.hpp"
-#include "oops/oop.inline.hpp"
-#include "runtime/thread.hpp"
-#include "services/memTracker.hpp"
-#include "utilities/align.hpp"
-#include "utilities/macros.hpp"
-
-// This kind of "BarrierSet" allows a "CollectedHeap" to detect and
-// enumerate ref fields that have been modified (since the last
-// enumeration.)
-
-CardTableModRefBS::CardTableModRefBS(
- CardTable* card_table,
- const BarrierSet::FakeRtti& fake_rtti) :
- ModRefBarrierSet(fake_rtti.add_tag(BarrierSet::CardTableModRef)),
- _defer_initial_card_mark(false),
- _card_table(card_table)
-{}
-
-CardTableModRefBS::CardTableModRefBS(CardTable* card_table) :
- ModRefBarrierSet(BarrierSet::FakeRtti(BarrierSet::CardTableModRef)),
- _defer_initial_card_mark(false),
- _card_table(card_table)
-{}
-
-void CardTableModRefBS::initialize() {
- initialize_deferred_card_mark_barriers();
-}
-
-CardTableModRefBS::~CardTableModRefBS() {
- delete _card_table;
-}
-
-void CardTableModRefBS::write_ref_array_work(MemRegion mr) {
- _card_table->dirty_MemRegion(mr);
-}
-
-void CardTableModRefBS::invalidate(MemRegion mr) {
- _card_table->invalidate(mr);
-}
-
-void CardTableModRefBS::print_on(outputStream* st) const {
- _card_table->print_on(st);
-}
-
-// Helper for ReduceInitialCardMarks. For performance,
-// compiled code may elide card-marks for initializing stores
-// to a newly allocated object along the fast-path. We
-// compensate for such elided card-marks as follows:
-// (a) Generational, non-concurrent collectors, such as
-// GenCollectedHeap(ParNew,DefNew,Tenured) and
-// ParallelScavengeHeap(ParallelGC, ParallelOldGC)
-// need the card-mark if and only if the region is
-// in the old gen, and do not care if the card-mark
-// succeeds or precedes the initializing stores themselves,
-// so long as the card-mark is completed before the next
-// scavenge. For all these cases, we can do a card mark
-// at the point at which we do a slow path allocation
-// in the old gen, i.e. in this call.
-// (b) GenCollectedHeap(ConcurrentMarkSweepGeneration) requires
-// in addition that the card-mark for an old gen allocated
-// object strictly follow any associated initializing stores.
-// In these cases, the memRegion remembered below is
-// used to card-mark the entire region either just before the next
-// slow-path allocation by this thread or just before the next scavenge or
-// CMS-associated safepoint, whichever of these events happens first.
-// (The implicit assumption is that the object has been fully
-// initialized by this point, a fact that we assert when doing the
-// card-mark.)
-// (c) G1CollectedHeap(G1) uses two kinds of write barriers. When a
-// G1 concurrent marking is in progress an SATB (pre-write-)barrier
-// is used to remember the pre-value of any store. Initializing
-// stores will not need this barrier, so we need not worry about
-// compensating for the missing pre-barrier here. Turning now
-// to the post-barrier, we note that G1 needs a RS update barrier
-// which simply enqueues a (sequence of) dirty cards which may
-// optionally be refined by the concurrent update threads. Note
-// that this barrier need only be applied to a non-young write,
-// but, like in CMS, because of the presence of concurrent refinement
-// (much like CMS' precleaning), must strictly follow the oop-store.
-// Thus, using the same protocol for maintaining the intended
-// invariants turns out, serendepitously, to be the same for both
-// G1 and CMS.
-//
-// For any future collector, this code should be reexamined with
-// that specific collector in mind, and the documentation above suitably
-// extended and updated.
-void CardTableModRefBS::on_slowpath_allocation_exit(JavaThread* thread, oop new_obj) {
-#if defined(COMPILER2) || INCLUDE_JVMCI
- if (!ReduceInitialCardMarks) {
- return;
- }
- // If a previous card-mark was deferred, flush it now.
- flush_deferred_card_mark_barrier(thread);
- if (new_obj->is_typeArray() || _card_table->is_in_young(new_obj)) {
- // Arrays of non-references don't need a post-barrier.
- // The deferred_card_mark region should be empty
- // following the flush above.
- assert(thread->deferred_card_mark().is_empty(), "Error");
- } else {
- MemRegion mr((HeapWord*)new_obj, new_obj->size());
- assert(!mr.is_empty(), "Error");
- if (_defer_initial_card_mark) {
- // Defer the card mark
- thread->set_deferred_card_mark(mr);
- } else {
- // Do the card mark
- invalidate(mr);
- }
- }
-#endif // COMPILER2 || JVMCI
-}
-
-void CardTableModRefBS::initialize_deferred_card_mark_barriers() {
- // Used for ReduceInitialCardMarks (when COMPILER2 or JVMCI is used);
- // otherwise remains unused.
-#if defined(COMPILER2) || INCLUDE_JVMCI
- _defer_initial_card_mark = is_server_compilation_mode_vm() && ReduceInitialCardMarks && can_elide_tlab_store_barriers()
- && (DeferInitialCardMark || card_mark_must_follow_store());
-#else
- assert(_defer_initial_card_mark == false, "Who would set it?");
-#endif
-}
-
-void CardTableModRefBS::flush_deferred_card_mark_barrier(JavaThread* thread) {
-#if defined(COMPILER2) || INCLUDE_JVMCI
- MemRegion deferred = thread->deferred_card_mark();
- if (!deferred.is_empty()) {
- assert(_defer_initial_card_mark, "Otherwise should be empty");
- {
- // Verify that the storage points to a parsable object in heap
- DEBUG_ONLY(oop old_obj = oop(deferred.start());)
- assert(!_card_table->is_in_young(old_obj),
- "Else should have been filtered in on_slowpath_allocation_exit()");
- assert(oopDesc::is_oop(old_obj, true), "Not an oop");
- assert(deferred.word_size() == (size_t)(old_obj->size()),
- "Mismatch: multiple objects?");
- }
- write_region(deferred);
- // "Clear" the deferred_card_mark field
- thread->set_deferred_card_mark(MemRegion());
- }
- assert(thread->deferred_card_mark().is_empty(), "invariant");
-#else
- assert(!_defer_initial_card_mark, "Should be false");
- assert(thread->deferred_card_mark().is_empty(), "Should be empty");
-#endif
-}
-
-void CardTableModRefBS::on_thread_detach(JavaThread* thread) {
- // The deferred store barriers must all have been flushed to the
- // card-table (or other remembered set structure) before GC starts
- // processing the card-table (or other remembered set).
- flush_deferred_card_mark_barrier(thread);
-}
-
-bool CardTableModRefBS::card_mark_must_follow_store() const {
- return _card_table->scanned_concurrently();
-}