1 /*
2 * Copyright (c) 2000, 2011, 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
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
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 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
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23 */
24
25 #ifndef SHARE_VM_MEMORY_BARRIERSET_HPP
26 #define SHARE_VM_MEMORY_BARRIERSET_HPP
27
28 #include "memory/memRegion.hpp"
29 #include "oops/oopsHierarchy.hpp"
30
31 // This class provides the interface between a barrier implementation and
32 // the rest of the system.
33
34 class BarrierSet: public CHeapObj {
35 friend class VMStructs;
36 public:
37 enum Name {
38 ModRef,
39 CardTableModRef,
40 CardTableExtension,
41 G1SATBCT,
42 G1SATBCTLogging,
43 Other,
44 Uninit
45 };
46
47 enum Flags {
48 None = 0,
49 TargetUninitialized = 1
50 };
51 protected:
52 int _max_covered_regions;
53 Name _kind;
54
55 public:
56
57 BarrierSet() { _kind = Uninit; }
58 // To get around prohibition on RTTI.
59 BarrierSet::Name kind() { return _kind; }
60 virtual bool is_a(BarrierSet::Name bsn) = 0;
61
62 // These operations indicate what kind of barriers the BarrierSet has.
63 virtual bool has_read_ref_barrier() = 0;
64 virtual bool has_read_prim_barrier() = 0;
65 virtual bool has_write_ref_barrier() = 0;
66 virtual bool has_write_ref_pre_barrier() = 0;
67 virtual bool has_write_prim_barrier() = 0;
68
69 // These functions indicate whether a particular access of the given
70 // kinds requires a barrier.
71 virtual bool read_ref_needs_barrier(void* field) = 0;
72 virtual bool read_prim_needs_barrier(HeapWord* field, size_t bytes) = 0;
73 virtual bool write_ref_needs_barrier(void* field, oop new_val) = 0;
74 virtual bool write_prim_needs_barrier(HeapWord* field, size_t bytes,
75 juint val1, juint val2) = 0;
76
77 // The first four operations provide a direct implementation of the
78 // barrier set. An interpreter loop, for example, could call these
79 // directly, as appropriate.
80
81 // Invoke the barrier, if any, necessary when reading the given ref field.
82 virtual void read_ref_field(void* field) = 0;
83
84 // Invoke the barrier, if any, necessary when reading the given primitive
85 // "field" of "bytes" bytes in "obj".
86 virtual void read_prim_field(HeapWord* field, size_t bytes) = 0;
87
88 // Invoke the barrier, if any, necessary when writing "new_val" into the
89 // ref field at "offset" in "obj".
90 // (For efficiency reasons, this operation is specialized for certain
91 // barrier types. Semantically, it should be thought of as a call to the
92 // virtual "_work" function below, which must implement the barrier.)
93 // First the pre-write versions...
94 template <class T> inline void write_ref_field_pre(T* field, oop new_val);
95 private:
96 // Keep this private so as to catch violations at build time.
97 virtual void write_ref_field_pre_work( void* field, oop new_val) { guarantee(false, "Not needed"); };
98 protected:
99 virtual void write_ref_field_pre_work( oop* field, oop new_val) {};
100 virtual void write_ref_field_pre_work(narrowOop* field, oop new_val) {};
101 public:
102
103 // ...then the post-write version.
104 inline void write_ref_field(void* field, oop new_val);
105 protected:
106 virtual void write_ref_field_work(void* field, oop new_val) = 0;
107 public:
108
109 // Invoke the barrier, if any, necessary when writing the "bytes"-byte
110 // value(s) "val1" (and "val2") into the primitive "field".
111 virtual void write_prim_field(HeapWord* field, size_t bytes,
112 juint val1, juint val2) = 0;
113
114 // Operations on arrays, or general regions (e.g., for "clone") may be
115 // optimized by some barriers.
116
117 // The first six operations tell whether such an optimization exists for
118 // the particular barrier.
119 virtual bool has_read_ref_array_opt() = 0;
120 virtual bool has_read_prim_array_opt() = 0;
121 virtual bool has_write_ref_array_pre_opt() { return true; }
122 virtual bool has_write_ref_array_opt() = 0;
123 virtual bool has_write_prim_array_opt() = 0;
124
125 virtual bool has_read_region_opt() = 0;
126 virtual bool has_write_region_opt() = 0;
127
128 // These operations should assert false unless the correponding operation
129 // above returns true. Otherwise, they should perform an appropriate
130 // barrier for an array whose elements are all in the given memory region.
131 virtual void read_ref_array(MemRegion mr) = 0;
132 virtual void read_prim_array(MemRegion mr) = 0;
133
134 // Below length is the # array elements being written
135 virtual void write_ref_array_pre(oop* dst, int length,
136 bool dest_uninitialized = false) {}
137 virtual void write_ref_array_pre(narrowOop* dst, int length,
138 bool dest_uninitialized = false) {}
139 // Below count is the # array elements being written, starting
140 // at the address "start", which may not necessarily be HeapWord-aligned
141 inline void write_ref_array(HeapWord* start, size_t count);
142
143 // Static versions, suitable for calling from generated code;
144 // count is # array elements being written, starting with "start",
145 // which may not necessarily be HeapWord-aligned.
146 static void static_write_ref_array_pre(HeapWord* start, size_t count);
147 static void static_write_ref_array_post(HeapWord* start, size_t count);
148
149 protected:
150 virtual void write_ref_array_work(MemRegion mr) = 0;
151 public:
152 virtual void write_prim_array(MemRegion mr) = 0;
153
154 virtual void read_region(MemRegion mr) = 0;
155
156 // (For efficiency reasons, this operation is specialized for certain
157 // barrier types. Semantically, it should be thought of as a call to the
158 // virtual "_work" function below, which must implement the barrier.)
159 inline void write_region(MemRegion mr);
160 protected:
161 virtual void write_region_work(MemRegion mr) = 0;
162 public:
163
164 // Some barrier sets create tables whose elements correspond to parts of
165 // the heap; the CardTableModRefBS is an example. Such barrier sets will
166 // normally reserve space for such tables, and commit parts of the table
167 // "covering" parts of the heap that are committed. The constructor is
168 // passed the maximum number of independently committable subregions to
169 // be covered, and the "resize_covoered_region" function allows the
170 // sub-parts of the heap to inform the barrier set of changes of their
171 // sizes.
172 BarrierSet(int max_covered_regions) :
173 _max_covered_regions(max_covered_regions) {}
174
175 // Inform the BarrierSet that the the covered heap region that starts
176 // with "base" has been changed to have the given size (possibly from 0,
177 // for initialization.)
178 virtual void resize_covered_region(MemRegion new_region) = 0;
179
180 // If the barrier set imposes any alignment restrictions on boundaries
181 // within the heap, this function tells whether they are met.
182 virtual bool is_aligned(HeapWord* addr) = 0;
183
184 // Print a description of the memory for the barrier set
185 virtual void print_on(outputStream* st) const = 0;
186 };
187
188 #endif // SHARE_VM_MEMORY_BARRIERSET_HPP