1 /*
2 * Copyright (c) 2014, 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_IMPLEMENTATION_G1_HEAPREGIONTYPE_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONTYPE_HPP
27
28 #include "memory/allocation.hpp"
29 #include "gc_implementation/g1/g1HeapRegionTraceType.hpp"
30
31 #define hrt_assert_is_valid(tag) \
32 assert(is_valid((tag)), err_msg("invalid HR type: %u", (uint) (tag)))
33
34 class HeapRegionType VALUE_OBJ_CLASS_SPEC {
35 private:
36 // We encode the value of the heap region type so the generation can be
37 // determined quickly. The tag is split into two parts:
38 //
39 // major type (young, humongous) : top N-1 bits
40 // minor type (eden / survivor, starts / cont hum, etc.) : bottom 1 bit
41 //
42 // If there's need to increase the number of minor types in the
43 // future, we'll have to increase the size of the latter and hence
44 // decrease the size of the former.
45 //
46 // 0000 0 [ 0] Free
47 //
48 // 0001 0 Young Mask
49 // 0001 0 [ 2] Eden
50 // 0001 1 [ 3] Survivor
51 //
52 // 0010 0 Humongous Mask
53 // 0010 0 [ 4] Humongous Starts
54 // 0010 1 [ 5] Humongous Continues
55 //
56 // 01000 [ 8] Old
57 typedef enum {
58 FreeTag = 0,
59
60 YoungMask = 2,
61 EdenTag = YoungMask,
62 SurvTag = YoungMask + 1,
63
64 HumMask = 4,
65 HumStartsTag = HumMask,
66 HumContTag = HumMask + 1,
67
68 OldTag = 8
69 } Tag;
70
71 volatile Tag _tag;
72
73 static bool is_valid(Tag tag);
74
75 Tag get() const {
76 hrt_assert_is_valid(_tag);
77 return _tag;
78 }
79
80 // Sets the type to 'tag'.
81 void set(Tag tag) {
82 hrt_assert_is_valid(tag);
83 hrt_assert_is_valid(_tag);
84 _tag = tag;
85 }
86
87 // Sets the type to 'tag', expecting the type to be 'before'. This
88 // is available for when we want to add sanity checking to the type
89 // transition.
90 void set_from(Tag tag, Tag before) {
91 hrt_assert_is_valid(tag);
92 hrt_assert_is_valid(before);
93 hrt_assert_is_valid(_tag);
94 assert(_tag == before,
95 err_msg("HR tag: %u, expected: %u new tag; %u", _tag, before, tag));
96 _tag = tag;
97 }
98
99 public:
100 // Queries
101
102 bool is_free() const { return get() == FreeTag; }
103
104 bool is_young() const { return (get() & YoungMask) != 0; }
105 bool is_eden() const { return get() == EdenTag; }
106 bool is_survivor() const { return get() == SurvTag; }
107
108 bool is_humongous() const { return (get() & HumMask) != 0; }
109 bool is_starts_humongous() const { return get() == HumStartsTag; }
110 bool is_continues_humongous() const { return get() == HumContTag; }
111
112 bool is_old() const { return get() == OldTag; }
113
114 // Setters
115
116 void set_free() { set(FreeTag); }
117
118 void set_eden() { set_from(EdenTag, FreeTag); }
119 void set_eden_pre_gc() { set_from(EdenTag, SurvTag); }
120 void set_survivor() { set_from(SurvTag, FreeTag); }
121
122 void set_starts_humongous() { set_from(HumStartsTag, FreeTag); }
123 void set_continues_humongous() { set_from(HumContTag, FreeTag); }
124
125 void set_old() { set(OldTag); }
126
127 // Misc
128
129 const char* get_str() const;
130 const char* get_short_str() const;
131 G1HeapRegionTraceType::Type get_trace_type();
132
133 HeapRegionType() : _tag(FreeTag) { hrt_assert_is_valid(_tag); }
134 };
135
136 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONTYPE_HPP