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8195103: Refactor out card table from CardTableModRefBS to flatten the BarrierSet hierarchy

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Reviewed-by: kbarrett, tschatzl
This commit is contained in:
Erik Österlund 2018-01-10 22:48:27 +01:00
parent ceb48aba9b
commit 0fb7dffb83
32 changed files with 282 additions and 372 deletions
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116
src/hotspot/share/gc/shared/collectedHeap.cpp
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2001, 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
@ -177,8 +177,7 @@ CollectedHeap::CollectedHeap() :
_total_collections(0),
_total_full_collections(0),
_gc_cause(GCCause::_no_gc),
_gc_lastcause(GCCause::_no_gc),
_defer_initial_card_mark(false) // strengthened by subclass in pre_initialize() below.
_gc_lastcause(GCCause::_no_gc)
{
const size_t max_len = size_t(arrayOopDesc::max_array_length(T_INT));
const size_t elements_per_word = HeapWordSize / sizeof(jint);
@ -239,17 +238,6 @@ void CollectedHeap::set_barrier_set(BarrierSet* barrier_set) {
BarrierSet::set_bs(barrier_set);
}
void CollectedHeap::pre_initialize() {
// Used for ReduceInitialCardMarks (when COMPILER2 is used);
// otherwise remains unused.
#if COMPILER2_OR_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
}
#ifndef PRODUCT
void CollectedHeap::check_for_bad_heap_word_value(HeapWord* addr, size_t size) {
if (CheckMemoryInitialization && ZapUnusedHeapArea) {
@ -333,28 +321,6 @@ HeapWord* CollectedHeap::allocate_from_tlab_slow(Klass* klass, Thread* thread, s
return obj;
}
void CollectedHeap::flush_deferred_store_barrier(JavaThread* thread) {
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(is_in(old_obj), "Not in allocated heap");
assert(!can_elide_initializing_store_barrier(old_obj),
"Else should have been filtered in new_store_pre_barrier()");
assert(oopDesc::is_oop(old_obj, true), "Not an oop");
assert(deferred.word_size() == (size_t)(old_obj->size()),
"Mismatch: multiple objects?");
}
BarrierSet* bs = barrier_set();
bs->write_region(deferred);
// "Clear" the deferred_card_mark field
thread->set_deferred_card_mark(MemRegion());
}
assert(thread->deferred_card_mark().is_empty(), "invariant");
}
size_t CollectedHeap::max_tlab_size() const {
// TLABs can't be bigger than we can fill with a int[Integer.MAX_VALUE].
// This restriction could be removed by enabling filling with multiple arrays.
@ -370,72 +336,6 @@ size_t CollectedHeap::max_tlab_size() const {
return align_down(max_int_size, MinObjAlignment);
}
// 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.
oop CollectedHeap::new_store_pre_barrier(JavaThread* thread, oop new_obj) {
// If a previous card-mark was deferred, flush it now.
flush_deferred_store_barrier(thread);
if (can_elide_initializing_store_barrier(new_obj) ||
new_obj->is_typeArray()) {
// Arrays of non-references don't need a pre-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
BarrierSet* bs = barrier_set();
bs->write_region(mr);
}
}
return new_obj;
}
size_t CollectedHeap::filler_array_hdr_size() {
return align_object_offset(arrayOopDesc::header_size(T_INT)); // align to Long
}
@ -538,24 +438,16 @@ void CollectedHeap::ensure_parsability(bool retire_tlabs) {
" otherwise concurrent mutator activity may make heap "
" unparsable again");
const bool use_tlab = UseTLAB;
const bool deferred = _defer_initial_card_mark;
// The main thread starts allocating via a TLAB even before it
// has added itself to the threads list at vm boot-up.
JavaThreadIteratorWithHandle jtiwh;
assert(!use_tlab || jtiwh.length() > 0,
"Attempt to fill tlabs before main thread has been added"
" to threads list is doomed to failure!");
BarrierSet *bs = barrier_set();
for (; JavaThread *thread = jtiwh.next(); ) {
if (use_tlab) thread->tlab().make_parsable(retire_tlabs);
#if COMPILER2_OR_JVMCI
// 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).
if (deferred) flush_deferred_store_barrier(thread);
#else
assert(!deferred, "Should be false");
assert(thread->deferred_card_mark().is_empty(), "Should be empty");
#endif
bs->make_parsable(thread);
}
}