1 /*
2 * Copyright (c) 2014, 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
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_GC_G1_HEAPREGIONTYPE_HPP
26 #define SHARE_VM_GC_G1_HEAPREGIONTYPE_HPP
27
28 #include "memory/allocation.hpp"
29
30 #define hrt_assert_is_valid(tag) \
31 assert(is_valid((tag)), "invalid HR type: %u", (uint) (tag))
32
33 class HeapRegionType VALUE_OBJ_CLASS_SPEC {
34 private:
35 // We encode the value of the heap region type so the generation can be
36 // determined quickly. The tag is split into two parts:
37 //
38 // major type (young, old, humongous, archive) : top N-1 bits
39 // minor type (eden / survivor, starts / cont hum, etc.) : bottom 1 bit
40 //
41 // If there's need to increase the number of minor types in the
42 // future, we'll have to increase the size of the latter and hence
43 // decrease the size of the former.
44 //
45 // 0000 0 [ 0] Free
46 //
47 // 0001 0 [ 2] Young Mask
48 // 0001 0 [ 2] Eden
49 // 0001 1 [ 3] Survivor
50 //
51 // 0010 0 [ 4] Humongous Mask
52 // 0100 0 [ 8] Pinned Mask
53 // 0110 0 [12] Starts Humongous
54 // 0110 1 [13] Continues Humongous
55 //
56 // 1000 0 [16] Old Mask
57 //
58 // 1100 0 [24] Archive
59 typedef enum {
60 FreeTag = 0,
61
62 YoungMask = 2,
63 EdenTag = YoungMask,
64 SurvTag = YoungMask + 1,
65
66 HumongousMask = 4,
67 PinnedMask = 8,
68 StartsHumongousTag = HumongousMask | PinnedMask,
69 ContinuesHumongousTag = HumongousMask | PinnedMask + 1,
70
71 OldMask = 16,
72 OldTag = OldMask,
73
74 ArchiveTag = PinnedMask | OldMask
75 } Tag;
76
77 volatile Tag _tag;
78
79 static bool is_valid(Tag tag);
80
81 Tag get() const {
82 hrt_assert_is_valid(_tag);
83 return _tag;
84 }
85
86 // Sets the type to 'tag'.
87 void set(Tag tag) {
88 hrt_assert_is_valid(tag);
89 hrt_assert_is_valid(_tag);
90 _tag = tag;
91 }
92
93 // Sets the type to 'tag', expecting the type to be 'before'. This
94 // is available for when we want to add sanity checking to the type
95 // transition.
96 void set_from(Tag tag, Tag before) {
97 hrt_assert_is_valid(tag);
98 hrt_assert_is_valid(before);
99 hrt_assert_is_valid(_tag);
100 assert(_tag == before, "HR tag: %u, expected: %u new tag; %u", _tag, before, tag);
101 _tag = tag;
102 }
103
104 public:
105 // Queries
106
107 bool is_free() const { return get() == FreeTag; }
108
109 bool is_young() const { return (get() & YoungMask) != 0; }
110 bool is_eden() const { return get() == EdenTag; }
111 bool is_survivor() const { return get() == SurvTag; }
112
113 bool is_humongous() const { return (get() & HumongousMask) != 0; }
114 bool is_starts_humongous() const { return get() == StartsHumongousTag; }
115 bool is_continues_humongous() const { return get() == ContinuesHumongousTag; }
116
117 bool is_archive() const { return get() == ArchiveTag; }
118
119 // is_old regions may or may not also be pinned
120 bool is_old() const { return (get() & OldMask) != 0; }
121
122 // is_pinned regions may be archive or humongous
123 bool is_pinned() const { return (get() & PinnedMask) != 0; }
124
125 // Setters
126
127 void set_free() { set(FreeTag); }
128
129 void set_eden() { set_from(EdenTag, FreeTag); }
130 void set_eden_pre_gc() { set_from(EdenTag, SurvTag); }
131 void set_survivor() { set_from(SurvTag, FreeTag); }
132
133 void set_starts_humongous() { set_from(StartsHumongousTag, FreeTag); }
134 void set_continues_humongous() { set_from(ContinuesHumongousTag, FreeTag); }
135
136 void set_old() { set(OldTag); }
137
138 void set_archive() { set_from(ArchiveTag, FreeTag); }
139
140 // Misc
141
142 const char* get_str() const;
143 const char* get_short_str() const;
144
145 HeapRegionType() : _tag(FreeTag) { hrt_assert_is_valid(_tag); }
146 };
147
148 #endif // SHARE_VM_GC_G1_HEAPREGIONTYPE_HPP