1 #ifdef USE_PRAGMA_IDENT_HDR
2 #pragma ident "@(#)barrierSet.hpp 1.18 07/05/05 17:05:43 JVM"
3 #endif
4 /*
5 * Copyright 2000-2008 Sun Microsystems, Inc. All Rights Reserved.
6 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
7 *
8 * This code is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License version 2 only, as
10 * published by the Free Software Foundation.
11 *
12 * This code is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 * version 2 for more details (a copy is included in the LICENSE file that
16 * accompanied this code).
17 *
18 * You should have received a copy of the GNU General Public License version
19 * 2 along with this work; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
21 *
22 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
23 * CA 95054 USA or visit www.sun.com if you need additional information or
24 * have any questions.
25 *
26 */
27
28 // This class provides the interface between a barrier implementation and
29 // the rest of the system.
30
31 class BarrierSet: public CHeapObj {
32 friend class VMStructs;
33 public:
34 enum Name {
35 ModRef,
36 CardTableModRef,
37 CardTableExtension,
38 G1SATBCT,
39 G1SATBCTLogging,
40 Other,
41 Uninit
42 };
43
44 protected:
45 int _max_covered_regions;
46 Name _kind;
47
48 public:
49
50 BarrierSet() { _kind = Uninit; }
51 // To get around prohibition on RTTI.
52 BarrierSet::Name kind() { return _kind; }
53 virtual bool is_a(BarrierSet::Name bsn) = 0;
54
55 // These operations indicate what kind of barriers the BarrierSet has.
56 virtual bool has_read_ref_barrier() = 0;
57 virtual bool has_read_prim_barrier() = 0;
58 virtual bool has_write_ref_barrier() = 0;
59 virtual bool has_write_ref_pre_barrier() = 0;
60 virtual bool has_write_prim_barrier() = 0;
61
62 // These functions indicate whether a particular access of the given
63 // kinds requires a barrier.
64 virtual bool read_ref_needs_barrier(void* field) = 0;
65 virtual bool read_prim_needs_barrier(HeapWord* field, size_t bytes) = 0;
66 virtual bool write_ref_needs_barrier(void* field, oop new_val) = 0;
67 virtual bool write_prim_needs_barrier(HeapWord* field, size_t bytes,
68 juint val1, juint val2) = 0;
69
70 // The first four operations provide a direct implementation of the
71 // barrier set. An interpreter loop, for example, could call these
72 // directly, as appropriate.
73
74 // Invoke the barrier, if any, necessary when reading the given ref field.
75 virtual void read_ref_field(void* field) = 0;
76
77 // Invoke the barrier, if any, necessary when reading the given primitive
78 // "field" of "bytes" bytes in "obj".
79 virtual void read_prim_field(HeapWord* field, size_t bytes) = 0;
80
81 // Invoke the barrier, if any, necessary when writing "new_val" into the
82 // ref field at "offset" in "obj".
83 // (For efficiency reasons, this operation is specialized for certain
84 // barrier types. Semantically, it should be thought of as a call to the
85 // virtual "_work" function below, which must implement the barrier.)
86 // First the pre-write versions...
87 inline void write_ref_field_pre(void* field, oop new_val);
88 protected:
89 virtual void write_ref_field_pre_work(void* field, oop new_val) {};
90 public:
91
92 // ...then the post-write version.
93 inline void write_ref_field(void* field, oop new_val);
94 protected:
95 virtual void write_ref_field_work(void* field, oop new_val) = 0;
96 public:
97
98 // Invoke the barrier, if any, necessary when writing the "bytes"-byte
99 // value(s) "val1" (and "val2") into the primitive "field".
100 virtual void write_prim_field(HeapWord* field, size_t bytes,
101 juint val1, juint val2) = 0;
102
103 // Operations on arrays, or general regions (e.g., for "clone") may be
104 // optimized by some barriers.
105
106 // The first six operations tell whether such an optimization exists for
107 // the particular barrier.
108 virtual bool has_read_ref_array_opt() = 0;
109 virtual bool has_read_prim_array_opt() = 0;
110 virtual bool has_write_ref_array_pre_opt() { return true; }
111 virtual bool has_write_ref_array_opt() = 0;
112 virtual bool has_write_prim_array_opt() = 0;
113
114 virtual bool has_read_region_opt() = 0;
115 virtual bool has_write_region_opt() = 0;
116
117 // These operations should assert false unless the correponding operation
118 // above returns true. Otherwise, they should perform an appropriate
119 // barrier for an array whose elements are all in the given memory region.
120 virtual void read_ref_array(MemRegion mr) = 0;
121 virtual void read_prim_array(MemRegion mr) = 0;
122
123 virtual void write_ref_array_pre(MemRegion mr) {}
124 inline void write_ref_array(MemRegion mr);
125
126 // Static versions, suitable for calling from generated code.
127 static void static_write_ref_array_pre(HeapWord* start, size_t count);
128 static void static_write_ref_array_post(HeapWord* start, size_t count);
129
130 protected:
131 virtual void write_ref_array_work(MemRegion mr) = 0;
132 public:
133 virtual void write_prim_array(MemRegion mr) = 0;
134
135 virtual void read_region(MemRegion mr) = 0;
136
137 // (For efficiency reasons, this operation is specialized for certain
138 // barrier types. Semantically, it should be thought of as a call to the
139 // virtual "_work" function below, which must implement the barrier.)
140 inline void write_region(MemRegion mr);
141 protected:
142 virtual void write_region_work(MemRegion mr) = 0;
143 public:
144
145 // Some barrier sets create tables whose elements correspond to parts of
146 // the heap; the CardTableModRefBS is an example. Such barrier sets will
147 // normally reserve space for such tables, and commit parts of the table
148 // "covering" parts of the heap that are committed. The constructor is
149 // passed the maximum number of independently committable subregions to
150 // be covered, and the "resize_covoered_region" function allows the
151 // sub-parts of the heap to inform the barrier set of changes of their
152 // sizes.
153 BarrierSet(int max_covered_regions) :
154 _max_covered_regions(max_covered_regions) {}
155
156 // Inform the BarrierSet that the the covered heap region that starts
157 // with "base" has been changed to have the given size (possibly from 0,
158 // for initialization.)
159 virtual void resize_covered_region(MemRegion new_region) = 0;
160
161 // If the barrier set imposes any alignment restrictions on boundaries
162 // within the heap, this function tells whether they are met.
163 virtual bool is_aligned(HeapWord* addr) = 0;
164
165 };