1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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24
25 #ifndef SHARE_GC_G1_G1BARRIERSET_HPP
26 #define SHARE_GC_G1_G1BARRIERSET_HPP
27
28 #include "gc/g1/g1SATBMarkQueueSet.hpp"
29 #include "gc/shared/bufferNode.hpp"
30 #include "gc/shared/cardTable.hpp"
31 #include "gc/shared/cardTableBarrierSet.hpp"
32
33 class G1CardTable;
34 class Thread;
35
36 // This barrier set is specialized to manage two card tables:
37 // * one the mutator is currently working on ("card table")
38 // * one the refinement threads or GC during pause are working on ("refinement table")
39 //
40 // The card table acts like a regular card table where the mutator dirties cards
41 // containing potentially interesting references.
42 //
43 // When the amount of dirty cards on the card table exceeds a threshold, G1 swaps
44 // the card tables and has the refinement threads reduce them by "refining"
45 // them.
46 // I.e. refinement looks at all dirty cards on the refinement table, and updates
47 // the remembered sets accordingly, clearing the cards on the refinement table.
48 //
49 // Meanwhile the mutator continues dirtying the now empty card table.
50 //
51 // This separation of data the mutator and refinement threads are working on
52 // removes the need for any fine-grained (per mutator write) synchronization between
53 // them, keeping the write barrier simple.
54 //
55 // The refinement threads mark cards in the current collection set specially on the
56 // card table - this is fine wrt synchronization with the mutator, because at
57 // most the mutator will overwrite it again if there is a race, as G1 will scan the
58 // entire card either way during the GC pause.
59 //
60 // During garbage collection, if the refinement table is known to be non-empty, G1
61 // merges it back (and cleaning it) to the card table which is scanned for dirty
62 // cards.
63 //
64 class G1BarrierSet: public CardTableBarrierSet {
65 private:
66 BufferNode::Allocator _satb_mark_queue_buffer_allocator;
67 G1SATBMarkQueueSet _satb_mark_queue_set;
68
69 G1CardTable* _refinement_table;
70
71 public:
72 G1BarrierSet(G1CardTable* card_table, G1CardTable* refinement_table);
73 virtual ~G1BarrierSet();
74
75 static G1BarrierSet* g1_barrier_set() {
76 return barrier_set_cast<G1BarrierSet>(BarrierSet::barrier_set());
77 }
78
79 G1CardTable* refinement_table() const { return _refinement_table; }
80
81 // Swap the global card table references, without synchronization.
82 void swap_global_card_table();
83
84 // Update the given thread's card table (byte map) base to the current card table's.
85 void update_card_table_base(Thread* thread);
86
87 virtual bool card_mark_must_follow_store() const {
88 return true;
89 }
90
91 // Add "pre_val" to a set of objects that may have been disconnected from the
92 // pre-marking object graph. Prefer the version that takes location, as it
93 // can avoid touching the heap unnecessarily.
94 template <class T> static void enqueue(T* dst);
95 static void enqueue_preloaded(oop pre_val);
96
97 static void enqueue_preloaded_if_weak(DecoratorSet decorators, oop value);
98
99 template <class T> void write_ref_array_pre_work(T* dst, size_t count);
100 virtual void write_ref_array_pre(oop* dst, size_t count, bool dest_uninitialized);
101 virtual void write_ref_array_pre(narrowOop* dst, size_t count, bool dest_uninitialized);
102
103 template <DecoratorSet decorators, typename T>
104 void write_ref_field_pre(T* field);
105
106 inline void write_region(MemRegion mr);
107 void write_region(JavaThread* thread, MemRegion mr);
108
109 template <DecoratorSet decorators = DECORATORS_NONE, typename T>
110 void write_ref_field_post(T* field);
111
112 virtual void on_thread_create(Thread* thread);
113 virtual void on_thread_destroy(Thread* thread);
114 virtual void on_thread_attach(Thread* thread);
115 virtual void on_thread_detach(Thread* thread);
116
117 static G1SATBMarkQueueSet& satb_mark_queue_set() {
118 return g1_barrier_set()->_satb_mark_queue_set;
119 }
120
121 virtual void print_on(outputStream* st) const;
122
123 // Callbacks for runtime accesses.
124 template <DecoratorSet decorators, typename BarrierSetT = G1BarrierSet>
125 class AccessBarrier: public ModRefBarrierSet::AccessBarrier<decorators, BarrierSetT> {
126 typedef ModRefBarrierSet::AccessBarrier<decorators, BarrierSetT> ModRef;
127 typedef BarrierSet::AccessBarrier<decorators, BarrierSetT> Raw;
128
129 public:
130 // Needed for loads on non-heap weak references
131 template <typename T>
132 static oop oop_load_not_in_heap(T* addr);
133
134 // Needed for non-heap stores
135 template <typename T>
136 static void oop_store_not_in_heap(T* addr, oop new_value);
137
138 // Needed for weak references
139 static oop oop_load_in_heap_at(oop base, ptrdiff_t offset);
140
141 // Defensive: will catch weak oops at addresses in heap
142 template <typename T>
143 static oop oop_load_in_heap(T* addr);
144
145 template <typename T>
146 static oop oop_atomic_cmpxchg_not_in_heap(T* addr, oop compare_value, oop new_value);
147 template <typename T>
148 static oop oop_atomic_xchg_not_in_heap(T* addr, oop new_value);
149 };
150 };
151
152 template<>
153 struct BarrierSet::GetName<G1BarrierSet> {
154 static const BarrierSet::Name value = BarrierSet::G1BarrierSet;
155 };
156
157 template<>
158 struct BarrierSet::GetType<BarrierSet::G1BarrierSet> {
159 typedef ::G1BarrierSet type;
160 };
161
162 #endif // SHARE_GC_G1_G1BARRIERSET_HPP