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.
4 *
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.
8 *
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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 *
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23 */
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 "asm/register.hpp"
31 #include "utilities/fakeRttiSupport.hpp"
32
33 // This class provides the interface between a barrier implementation and
34 // the rest of the system.
35
36 class MacroAssembler;
37
38 class BarrierSet: public CHeapObj<mtGC> {
39 friend class VMStructs;
40 public:
41 // Fake RTTI support. For a derived class T to participate
42 // - T must have a corresponding Name entry.
43 // - GetName<T> must be specialized to return the corresponding Name
44 // entry.
45 // - If T is a base class, the constructor must have a FakeRtti
46 // parameter and pass it up to its base class, with the tag set
47 // augmented with the corresponding Name entry.
48 // - If T is a concrete class, the constructor must create a
49 // FakeRtti object whose tag set includes the corresponding Name
50 // entry, and pass it up to its base class.
51
52 enum Name { // associated class
53 ModRef, // ModRefBarrierSet
54 CardTableModRef, // CardTableModRefBS
55 CardTableForRS, // CardTableModRefBSForCTRS
56 CardTableExtension, // CardTableExtension
57 G1SATBCT, // G1SATBCardTableModRefBS
58 G1SATBCTLogging, // G1SATBCardTableLoggingModRefBS
59 ShenandoahBarrierSet // ShenandoahBarrierSet
60 };
61
62 protected:
63 typedef FakeRttiSupport<BarrierSet, Name> FakeRtti;
64
65 private:
66 FakeRtti _fake_rtti;
67
68 // Metafunction mapping a class derived from BarrierSet to the
69 // corresponding Name enum tag.
70 template<typename T> struct GetName;
71
72 // Downcast argument to a derived barrier set type.
73 // The cast is checked in a debug build.
74 // T must have a specialization for BarrierSet::GetName<T>.
75 template<typename T> friend T* barrier_set_cast(BarrierSet* bs);
76
77 public:
78 // Note: This is not presently the Name corresponding to the
79 // concrete class of this object.
80 BarrierSet::Name kind() const { return _fake_rtti.concrete_tag(); }
81
82 // Test whether this object is of the type corresponding to bsn.
83 bool is_a(BarrierSet::Name bsn) const { return _fake_rtti.has_tag(bsn); }
84
85 // End of fake RTTI support.
86
87 public:
88 enum Flags {
89 None = 0,
90 TargetUninitialized = 1
91 };
92
93 protected:
94 // Some barrier sets create tables whose elements correspond to parts of
95 // the heap; the CardTableModRefBS is an example. Such barrier sets will
96 // normally reserve space for such tables, and commit parts of the table
97 // "covering" parts of the heap that are committed. At most one covered
98 // region per generation is needed.
99 static const int _max_covered_regions = 2;
100
101 BarrierSet(const FakeRtti& fake_rtti) : _fake_rtti(fake_rtti) { }
102 ~BarrierSet() { }
103
104 public:
105
106 // These operations indicate what kind of barriers the BarrierSet has.
107 virtual bool has_read_ref_barrier() = 0;
108 virtual bool has_read_prim_barrier() = 0;
109 virtual bool has_write_ref_barrier() = 0;
110 virtual bool has_write_ref_pre_barrier() = 0;
111 virtual bool has_write_prim_barrier() = 0;
112
113 // These functions indicate whether a particular access of the given
114 // kinds requires a barrier.
115 virtual bool read_ref_needs_barrier(void* field) = 0;
116 virtual bool read_prim_needs_barrier(HeapWord* field, size_t bytes) = 0;
117 virtual bool write_prim_needs_barrier(HeapWord* field, size_t bytes,
118 juint val1, juint val2) = 0;
119
120 // The first four operations provide a direct implementation of the
121 // barrier set. An interpreter loop, for example, could call these
122 // directly, as appropriate.
123
124 // Invoke the barrier, if any, necessary when reading the given ref field.
125 virtual void read_ref_field(void* field) = 0;
126
127 // Invoke the barrier, if any, necessary when reading the given primitive
128 // "field" of "bytes" bytes in "obj".
129 virtual void read_prim_field(HeapWord* field, size_t bytes) = 0;
130
131 // Invoke the barrier, if any, necessary when writing "new_val" into the
132 // ref field at "offset" in "obj".
133 // (For efficiency reasons, this operation is specialized for certain
134 // barrier types. Semantically, it should be thought of as a call to the
135 // virtual "_work" function below, which must implement the barrier.)
136 // First the pre-write versions...
137 template <class T> inline void write_ref_field_pre(T* field, oop new_val);
138 private:
139 // Helper for write_ref_field_pre and friends, testing for specialized cases.
140 bool devirtualize_reference_writes() const;
141
142 // Keep this private so as to catch violations at build time.
143 virtual void write_ref_field_pre_work( void* field, oop new_val) { guarantee(false, "Not needed"); };
144 protected:
145 virtual void write_ref_field_pre_work( oop* field, oop new_val) {};
146 virtual void write_ref_field_pre_work(narrowOop* field, oop new_val) {};
147 public:
148
149 // ...then the post-write version.
150 inline void write_ref_field(void* field, oop new_val, bool release = false);
151 protected:
152 virtual void write_ref_field_work(void* field, oop new_val, bool release) = 0;
153 public:
154
155 // Invoke the barrier, if any, necessary when writing the "bytes"-byte
156 // value(s) "val1" (and "val2") into the primitive "field".
157 virtual void write_prim_field(HeapWord* field, size_t bytes,
158 juint val1, juint val2) = 0;
159
160 // Operations on arrays, or general regions (e.g., for "clone") may be
161 // optimized by some barriers.
162
163 // The first six operations tell whether such an optimization exists for
164 // the particular barrier.
165 virtual bool has_read_ref_array_opt() = 0;
166 virtual bool has_read_prim_array_opt() = 0;
167 virtual bool has_write_ref_array_pre_opt() { return true; }
168 virtual bool has_write_ref_array_opt() = 0;
169 virtual bool has_write_prim_array_opt() = 0;
170
171 virtual bool has_read_region_opt() = 0;
172 virtual bool has_write_region_opt() = 0;
173
174 // These operations should assert false unless the corresponding operation
175 // above returns true. Otherwise, they should perform an appropriate
176 // barrier for an array whose elements are all in the given memory region.
177 virtual void read_ref_array(MemRegion mr) = 0;
178 virtual void read_prim_array(MemRegion mr) = 0;
179
180 // Below length is the # array elements being written
181 virtual void write_ref_array_pre(oop* dst, int length,
182 bool dest_uninitialized = false) {}
183 virtual void write_ref_array_pre(narrowOop* dst, int length,
184 bool dest_uninitialized = false) {}
185 // Below count is the # array elements being written, starting
186 // at the address "start", which may not necessarily be HeapWord-aligned
187 inline void write_ref_array(HeapWord* start, size_t count);
188
189 // Static versions, suitable for calling from generated code;
190 // count is # array elements being written, starting with "start",
191 // which may not necessarily be HeapWord-aligned.
192 static void static_write_ref_array_pre(HeapWord* start, size_t count);
193 static void static_write_ref_array_post(HeapWord* start, size_t count);
194
195 protected:
196 virtual void write_ref_array_work(MemRegion mr) = 0;
197 public:
198 virtual void write_prim_array(MemRegion mr) = 0;
199
200 virtual void read_region(MemRegion mr) = 0;
201
202 // (For efficiency reasons, this operation is specialized for certain
203 // barrier types. Semantically, it should be thought of as a call to the
204 // virtual "_work" function below, which must implement the barrier.)
205 void write_region(MemRegion mr);
206 protected:
207 virtual void write_region_work(MemRegion mr) = 0;
208 public:
209 // Inform the BarrierSet that the the covered heap region that starts
210 // with "base" has been changed to have the given size (possibly from 0,
211 // for initialization.)
212 virtual void resize_covered_region(MemRegion new_region) = 0;
213
214 // If the barrier set imposes any alignment restrictions on boundaries
215 // within the heap, this function tells whether they are met.
216 virtual bool is_aligned(HeapWord* addr) = 0;
217
218 // Print a description of the memory for the barrier set
219 virtual void print_on(outputStream* st) const = 0;
220
221 virtual oop read_barrier(oop src) {
222 return src;
223 }
224 virtual oop write_barrier(oop src) {
225 return src;
226 }
227 virtual oop resolve_and_update_oop(oop* p, oop obj) {
228 return obj;
229 }
230 virtual oop resolve_and_update_oop(narrowOop* p, oop obj) {
231 return obj;
232 }
233 #ifndef CC_INTERP
234 virtual void interpreter_read_barrier(MacroAssembler* masm, Register dst) {
235 // Default implementation does nothing.
236 }
237
238 virtual void interpreter_read_barrier_not_null(MacroAssembler* masm, Register dst) {
239 // Default implementation does nothing.
240 }
241
242 virtual void interpreter_write_barrier(MacroAssembler* masm, Register dst) {
243 // Default implementation does nothing.
244 }
245 #endif
246 };
247
248 template<typename T>
249 inline T* barrier_set_cast(BarrierSet* bs) {
250 assert(bs->is_a(BarrierSet::GetName<T>::value), "wrong type of barrier set");
251 return static_cast<T*>(bs);
252 }
253
254 #endif // SHARE_VM_GC_SHARED_BARRIERSET_HPP