1 /*
2 * Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
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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).
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24
25 #ifndef SHARE_VM_GC_SHARED_BARRIERSET_HPP
26 #define SHARE_VM_GC_SHARED_BARRIERSET_HPP
27
28 #include "memory/memRegion.hpp"
29 #include "oops/oopsHierarchy.hpp"
30 #include "utilities/fakeRttiSupport.hpp"
31
32 // This class provides the interface between a barrier implementation and
33 // the rest of the system.
34
35 class BarrierSet: public CHeapObj<mtGC> {
36 friend class VMStructs;
37 public:
38 // Fake RTTI support. For a derived class T to participate
39 // - T must have a corresponding Name entry.
40 // - GetName<T> must be specialized to return the corresponding Name
41 // entry.
42 // - If T is a base class, the constructor must have a FakeRtti
43 // parameter and pass it up to its base class, with the tag set
44 // augmented with the corresponding Name entry.
45 // - If T is a concrete class, the constructor must create a
46 // FakeRtti object whose tag set includes the corresponding Name
47 // entry, and pass it up to its base class.
48
49 enum Name { // associated class
50 ModRef, // ModRefBarrierSet
51 CardTableModRef, // CardTableModRefBS
52 CardTableForRS, // CardTableModRefBSForCTRS
53 CardTableExtension, // CardTableExtension
54 G1SATBCT, // G1SATBCardTableModRefBS
55 G1SATBCTLogging // G1SATBCardTableLoggingModRefBS
56 };
57
58 protected:
59 typedef FakeRttiSupport<BarrierSet, Name> FakeRtti;
60
61 private:
62 FakeRtti _fake_rtti;
63
64 // Metafunction mapping a class derived from BarrierSet to the
65 // corresponding Name enum tag.
66 template<typename T> struct GetName;
67
68 // Downcast argument to a derived barrier set type.
69 // The cast is checked in a debug build.
70 // T must have a specialization for BarrierSet::GetName<T>.
71 template<typename T> friend T* barrier_set_cast(BarrierSet* bs);
72
73 public:
74 // Note: This is not presently the Name corresponding to the
75 // concrete class of this object.
76 BarrierSet::Name kind() const { return _fake_rtti.concrete_tag(); }
77
78 // Test whether this object is of the type corresponding to bsn.
79 bool is_a(BarrierSet::Name bsn) const { return _fake_rtti.has_tag(bsn); }
80
81 // End of fake RTTI support.
82
83 public:
84 enum Flags {
85 None = 0,
86 TargetUninitialized = 1
87 };
88
89 protected:
90 // Some barrier sets create tables whose elements correspond to parts of
91 // the heap; the CardTableModRefBS is an example. Such barrier sets will
92 // normally reserve space for such tables, and commit parts of the table
93 // "covering" parts of the heap that are committed. At most one covered
94 // region per generation is needed.
95 static const int _max_covered_regions = 2;
96
97 BarrierSet(const FakeRtti& fake_rtti) : _fake_rtti(fake_rtti) { }
98 ~BarrierSet() { }
99
100 public:
101
102 // These operations indicate what kind of barriers the BarrierSet has.
103 virtual bool has_read_ref_barrier() = 0;
104 virtual bool has_read_prim_barrier() = 0;
105 virtual bool has_write_ref_barrier() = 0;
106 virtual bool has_write_ref_pre_barrier() = 0;
107 virtual bool has_write_prim_barrier() = 0;
108
109 // These functions indicate whether a particular access of the given
110 // kinds requires a barrier.
111 virtual bool read_ref_needs_barrier(void* field) = 0;
112 virtual bool read_prim_needs_barrier(HeapWord* field, size_t bytes) = 0;
113 virtual bool write_prim_needs_barrier(HeapWord* field, size_t bytes,
114 juint val1, juint val2) = 0;
115
116 // The first four operations provide a direct implementation of the
117 // barrier set. An interpreter loop, for example, could call these
118 // directly, as appropriate.
119
120 // Invoke the barrier, if any, necessary when reading the given ref field.
121 virtual void read_ref_field(void* field) = 0;
122
123 // Invoke the barrier, if any, necessary when reading the given primitive
124 // "field" of "bytes" bytes in "obj".
125 virtual void read_prim_field(HeapWord* field, size_t bytes) = 0;
126
127 // Invoke the barrier, if any, necessary when writing "new_val" into the
128 // ref field at "offset" in "obj".
129 // (For efficiency reasons, this operation is specialized for certain
130 // barrier types. Semantically, it should be thought of as a call to the
131 // virtual "_work" function below, which must implement the barrier.)
132 // First the pre-write versions...
133 template <class T> inline void write_ref_field_pre(T* field, oop new_val);
134 private:
135 // Helper for write_ref_field_pre and friends, testing for specialized cases.
136 bool devirtualize_reference_writes() const;
137
138 // Keep this private so as to catch violations at build time.
139 virtual void write_ref_field_pre_work( void* field, oop new_val) { guarantee(false, "Not needed"); };
140 protected:
141 virtual void write_ref_field_pre_work( oop* field, oop new_val) {};
142 virtual void write_ref_field_pre_work(narrowOop* field, oop new_val) {};
143 public:
144
145 // ...then the post-write version.
146 inline void write_ref_field(void* field, oop new_val, bool release = false);
147 protected:
148 virtual void write_ref_field_work(void* field, oop new_val, bool release) = 0;
149 public:
150
151 // Invoke the barrier, if any, necessary when writing the "bytes"-byte
152 // value(s) "val1" (and "val2") into the primitive "field".
153 virtual void write_prim_field(HeapWord* field, size_t bytes,
154 juint val1, juint val2) = 0;
155
156 // Operations on arrays, or general regions (e.g., for "clone") may be
157 // optimized by some barriers.
158
159 // The first six operations tell whether such an optimization exists for
160 // the particular barrier.
161 virtual bool has_read_ref_array_opt() = 0;
162 virtual bool has_read_prim_array_opt() = 0;
163 virtual bool has_write_ref_array_pre_opt() { return true; }
164 virtual bool has_write_ref_array_opt() = 0;
165 virtual bool has_write_prim_array_opt() = 0;
166
167 virtual bool has_read_region_opt() = 0;
168 virtual bool has_write_region_opt() = 0;
169
170 // These operations should assert false unless the corresponding operation
171 // above returns true. Otherwise, they should perform an appropriate
172 // barrier for an array whose elements are all in the given memory region.
173 virtual void read_ref_array(MemRegion mr) = 0;
174 virtual void read_prim_array(MemRegion mr) = 0;
175
176 // Below length is the # array elements being written
177 virtual void write_ref_array_pre(oop* dst, int length,
178 bool dest_uninitialized = false) {}
179 virtual void write_ref_array_pre(narrowOop* dst, int length,
180 bool dest_uninitialized = false) {}
181 // Below count is the # array elements being written, starting
182 // at the address "start", which may not necessarily be HeapWord-aligned
183 inline void write_ref_array(HeapWord* start, size_t count);
184
185 // Static versions, suitable for calling from generated code;
186 // count is # array elements being written, starting with "start",
187 // which may not necessarily be HeapWord-aligned.
188 static void static_write_ref_array_pre(HeapWord* start, size_t count);
189 static void static_write_ref_array_post(HeapWord* start, size_t count);
190
191 protected:
192 virtual void write_ref_array_work(MemRegion mr) = 0;
193 public:
194 virtual void write_prim_array(MemRegion mr) = 0;
195
196 virtual void read_region(MemRegion mr) = 0;
197
198 // (For efficiency reasons, this operation is specialized for certain
199 // barrier types. Semantically, it should be thought of as a call to the
200 // virtual "_work" function below, which must implement the barrier.)
201 void write_region(MemRegion mr);
202 protected:
203 virtual void write_region_work(MemRegion mr) = 0;
204 public:
205 // Inform the BarrierSet that the the covered heap region that starts
206 // with "base" has been changed to have the given size (possibly from 0,
207 // for initialization.)
208 virtual void resize_covered_region(MemRegion new_region) = 0;
209
210 // If the barrier set imposes any alignment restrictions on boundaries
211 // within the heap, this function tells whether they are met.
212 virtual bool is_aligned(HeapWord* addr) = 0;
213
214 // Print a description of the memory for the barrier set
215 virtual void print_on(outputStream* st) const = 0;
216 };
217
218 template<typename T>
219 inline T* barrier_set_cast(BarrierSet* bs) {
220 assert(bs->is_a(BarrierSet::GetName<T>::value), "wrong type of barrier set");
221 return static_cast<T*>(bs);
222 }
223
224 #endif // SHARE_VM_GC_SHARED_BARRIERSET_HPP