heapRegionType.hpp revision 9056:dc9930a04ab0 
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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
33class HeapRegionType VALUE_OBJ_CLASS_SPEC {
34private:
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
104public:
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
149