1 /*
2 * Copyright (c) 2000, 2010, 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.
18 *
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
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_VM_MEMORY_MODREFBARRIERSET_HPP
26 #define SHARE_VM_MEMORY_MODREFBARRIERSET_HPP
27
28 #include "memory/barrierSet.hpp"
29
30 // This kind of "BarrierSet" allows a "CollectedHeap" to detect and
31 // enumerate ref fields that have been modified (since the last
32 // enumeration), using a card table.
33
34 class OopClosure;
35 class Generation;
36
37 class ModRefBarrierSet: public BarrierSet {
38 public:
39
40 ModRefBarrierSet() { _kind = BarrierSet::ModRef; }
41
42 bool is_a(BarrierSet::Name bsn) {
43 return bsn == BarrierSet::ModRef;
44 }
45
46 // Barriers only on ref writes.
47 bool has_read_ref_barrier() { return false; }
48 bool has_read_prim_barrier() { return false; }
49 bool has_write_ref_barrier() { return true; }
50 bool has_write_prim_barrier() { return false; }
51
52 bool read_ref_needs_barrier(void* field) { return false; }
53 bool read_prim_needs_barrier(HeapWord* field, size_t bytes) { return false; }
54 virtual bool write_ref_needs_barrier(void* field, oop new_val) = 0;
55 bool write_prim_needs_barrier(HeapWord* field, size_t bytes,
56 juint val1, juint val2) { return false; }
57
58 void write_prim_field(oop obj, size_t offset, size_t bytes,
59 juint val1, juint val2) {}
60
61 void read_ref_field(void* field) {}
62 void read_prim_field(HeapWord* field, size_t bytes) {}
63 protected:
64 virtual void write_ref_field_work(void* field, oop new_val) = 0;
65 public:
66 void write_prim_field(HeapWord* field, size_t bytes,
67 juint val1, juint val2) {}
68
69 bool has_read_ref_array_opt() { return false; }
70 bool has_read_prim_array_opt() { return false; }
71 bool has_write_prim_array_opt() { return false; }
72
73 bool has_read_region_opt() { return false; }
74
75
76 // These operations should assert false unless the correponding operation
77 // above returns true.
78 void read_ref_array(MemRegion mr) {
79 assert(false, "can't call");
80 }
81 void read_prim_array(MemRegion mr) {
82 assert(false, "can't call");
83 }
84 void write_prim_array(MemRegion mr) {
85 assert(false, "can't call");
86 }
87 void read_region(MemRegion mr) {
88 assert(false, "can't call");
89 }
90
91 // Invoke "cl->do_oop" on (the address of) every possibly-modifed
92 // reference field in objects in "sp". If "clear" is "true", the oops
93 // are no longer considered possibly modified after application of the
94 // closure. If' "before_save_marks" is true, oops in objects allocated
95 // after the last call to "save_marks" on "sp" will not be considered.
96 virtual void mod_oop_in_space_iterate(Space* sp, OopClosure* cl,
97 bool clear = false,
98 bool before_save_marks = false) = 0;
99
100 // Causes all refs in "mr" to be assumed to be modified. If "whole_heap"
101 // is true, the caller asserts that the entire heap is being invalidated,
102 // which may admit an optimized implementation for some barriers.
103 virtual void invalidate(MemRegion mr, bool whole_heap = false) = 0;
104
105 // The caller guarantees that "mr" contains no references. (Perhaps it's
106 // objects have been moved elsewhere.)
107 virtual void clear(MemRegion mr) = 0;
108
109 // Pass along the argument to the superclass.
110 ModRefBarrierSet(int max_covered_regions) :
111 BarrierSet(max_covered_regions) {}
112
113 #ifndef PRODUCT
114 // Verifies that the given region contains no modified references.
115 virtual void verify_clean_region(MemRegion mr) = 0;
116 #endif
117
118 };
119
120 #endif // SHARE_VM_MEMORY_MODREFBARRIERSET_HPP