1 /*
2 * Copyright (c) 2014, 2018, 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
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23 */
24
25 #ifndef SHARE_VM_GC_G1_HEAPREGIONTYPE_HPP
26 #define SHARE_VM_GC_G1_HEAPREGIONTYPE_HPP
27
28 #include "gc/g1/g1HeapRegionTraceType.hpp"
29
30 #define hrt_assert_is_valid(tag) \
31 assert(is_valid((tag)), "invalid HR type: %u", (uint) (tag))
32
33 class HeapRegionType {
34 friend class VMStructs;
35
36 private:
37 // We encode the value of the heap region type so the generation can be
38 // determined quickly. The tag is split into two parts:
39 //
40 // major type (young, old, humongous, archive) : top N-1 bits
41 // minor type (eden / survivor, starts / cont hum, etc.) : bottom 1 bit
42 //
43 // If there's need to increase the number of minor types in the
44 // future, we'll have to increase the size of the latter and hence
45 // decrease the size of the former.
46 //
47 // 00000 0 [ 0] Free
48 //
49 // 00001 0 [ 2] Young Mask
50 // 00001 0 [ 2] Eden
51 // 00001 1 [ 3] Survivor
52 //
53 // 00010 0 [ 4] Humongous Mask
54 // 00100 0 [ 8] Pinned Mask
55 // 00110 0 [12] Starts Humongous
56 // 00110 1 [13] Continues Humongous
57 //
58 // 01000 0 [16] Old Mask
59 //
60 // 10000 0 [32] Archive Mask
61 // 11100 0 [56] Open Archive
62 // 11100 1 [57] Closed Archive
63 //
64 typedef enum {
65 FreeTag = 0,
66
67 YoungMask = 2,
68 EdenTag = YoungMask,
69 SurvTag = YoungMask + 1,
70
71 HumongousMask = 4,
72 PinnedMask = 8,
73 StartsHumongousTag = HumongousMask | PinnedMask,
74 ContinuesHumongousTag = HumongousMask | PinnedMask + 1,
75
76 OldMask = 16,
77 PreMatureOldMask = OldMask + 1,
78 OldTag = OldMask,
79 PreMatureOldTag = PreMatureOldMask,
80
81 // Archive regions are regions with immutable content (i.e. not reclaimed, and
82 // not allocated into during regular operation). They differ in the kind of references
83 // allowed for the contained objects:
84 // - Closed archive regions form a separate self-contained (closed) object graph
85 // within the set of all of these regions. No references outside of closed
86 // archive regions are allowed.
87 // - Open archive regions have no restrictions on the references of their objects.
88 // Objects within these regions are allowed to have references to objects
89 // contained in any other kind of regions.
90 ArchiveMask = 32,
91 OpenArchiveTag = ArchiveMask | PinnedMask,
92 ClosedArchiveTag = ArchiveMask | PinnedMask + 1
93 } Tag;
94
95 volatile Tag _tag;
96
97 static bool is_valid(Tag tag);
98
99 Tag get() const {
100 hrt_assert_is_valid(_tag);
101 return _tag;
102 }
103
104 // Sets the type to 'tag'.
105 void set(Tag tag) {
106 hrt_assert_is_valid(tag);
107 hrt_assert_is_valid(_tag);
108 _tag = tag;
109 }
110
111 // Sets the type to 'tag', expecting the type to be 'before'. This
112 // is available for when we want to add sanity checking to the type
113 // transition.
114 void set_from(Tag tag, Tag before) {
115 hrt_assert_is_valid(tag);
116 hrt_assert_is_valid(before);
117 hrt_assert_is_valid(_tag);
118 assert(_tag == before, "HR tag: %u, expected: %u new tag; %u", _tag, before, tag);
119 _tag = tag;
120 }
121
122 public:
123 // Queries
124
125 bool is_free() const { return get() == FreeTag; }
126
127 bool is_young() const { return (get() & YoungMask) != 0; }
128 bool is_eden() const { return get() == EdenTag; }
129 bool is_survivor() const { return get() == SurvTag; }
130
131 bool is_humongous() const { return (get() & HumongousMask) != 0; }
132 bool is_starts_humongous() const { return get() == StartsHumongousTag; }
133 bool is_continues_humongous() const { return get() == ContinuesHumongousTag; }
134
135 bool is_archive() const { return (get() & ArchiveMask) != 0; }
136 bool is_open_archive() const { return get() == OpenArchiveTag; }
137 bool is_closed_archive() const { return get() == ClosedArchiveTag; }
138
139 // is_old regions may or may not also be pinned
140 bool is_old() const { return (get() & OldMask) != 0; }
141
142 bool is_premature_old() const { return get() == PreMatureOldTag; }
143
144 bool is_old_or_humongous() const { return (get() & (OldMask | HumongousMask)) != 0; }
145
146 bool is_old_or_humongous_or_archive() const { return (get() & (OldMask | HumongousMask | ArchiveMask)) != 0; }
147
148 // is_pinned regions may be archive or humongous
149 bool is_pinned() const { return (get() & PinnedMask) != 0; }
150
151 // Setters
152
153 void set_free() { set(FreeTag); }
154
155 void set_eden() { set_from(EdenTag, FreeTag); }
156 void set_eden_pre_gc() { set_from(EdenTag, SurvTag); }
157 void set_survivor() { set_from(SurvTag, FreeTag); }
158
159 void set_starts_humongous() { set_from(StartsHumongousTag, FreeTag); }
160 void set_continues_humongous() { set_from(ContinuesHumongousTag, FreeTag); }
161
162 void set_old() { set(OldTag); }
163
164 void set_premature_old() { set(PreMatureOldTag); }
165
166 // Change the current region type to be of an old region type if not already done so.
167 // Returns whether the region type has been changed or not.
168 bool relabel_as_old() {
169 //assert(!is_free(), "Should not try to move Free region");
170 assert(!is_humongous(), "Should not try to move Humongous region");
171 if (is_old()) {
172 return false;
173 }
174 if (is_eden()) {
175 set_from(OldTag, EdenTag);
176 return true;
177 } else if (is_free()) {
178 set_from(OldTag, FreeTag);
179 return true;
180 } else {
181 set_from(OldTag, SurvTag);
182 return true;
183 }
184 }
185 void set_open_archive() { set_from(OpenArchiveTag, FreeTag); }
186 void set_closed_archive() { set_from(ClosedArchiveTag, FreeTag); }
187
188 // Misc
189
190 const char* get_str() const;
191 const char* get_short_str() const;
192 G1HeapRegionTraceType::Type get_trace_type();
193
194 HeapRegionType() : _tag(FreeTag) { hrt_assert_is_valid(_tag); }
195 };
196
197 #endif // SHARE_VM_GC_G1_HEAPREGIONTYPE_HPP