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24
25#ifndef SHARE_GC_PARALLEL_PARMARKBITMAP_HPP
26#define SHARE_GC_PARALLEL_PARMARKBITMAP_HPP
27
28#include "memory/memRegion.hpp"
29#include "oops/oop.hpp"
30#include "utilities/bitMap.hpp"
31
32class ParMarkBitMapClosure;
33class PSVirtualSpace;
34class ParCompactionManager;
35
36class ParMarkBitMap: public CHeapObj<mtGC>
37{
38public:
39 typedef BitMap::idx_t idx_t;
40
41 // Values returned by the iterate() methods.
42 enum IterationStatus { incomplete, complete, full, would_overflow };
43
44 inline ParMarkBitMap();
45 bool initialize(MemRegion covered_region);
46
47 // Atomically mark an object as live.
48 bool mark_obj(HeapWord* addr, size_t size);
49 inline bool mark_obj(oop obj, int size);
50
51 // Return whether the specified begin or end bit is set.
52 inline bool is_obj_beg(idx_t bit) const;
53 inline bool is_obj_end(idx_t bit) const;
54
55 // Traditional interface for testing whether an object is marked or not (these
56 // test only the begin bits).
57 inline bool is_marked(idx_t bit) const;
58 inline bool is_marked(HeapWord* addr) const;
59 inline bool is_marked(oop obj) const;
60
61 inline bool is_unmarked(idx_t bit) const;
62 inline bool is_unmarked(HeapWord* addr) const;
63 inline bool is_unmarked(oop obj) const;
64
65 // Convert sizes from bits to HeapWords and back. An object that is n bits
66 // long will be bits_to_words(n) words long. An object that is m words long
67 // will take up words_to_bits(m) bits in the bitmap.
68 inline static size_t bits_to_words(idx_t bits);
69 inline static idx_t words_to_bits(size_t words);
70
71 // Return the size in words of an object given a begin bit and an end bit, or
72 // the equivalent beg_addr and end_addr.
73 inline size_t obj_size(idx_t beg_bit, idx_t end_bit) const;
74 inline size_t obj_size(HeapWord* beg_addr, HeapWord* end_addr) const;
75
76 // Return the size in words of the object (a search is done for the end bit).
77 inline size_t obj_size(idx_t beg_bit) const;
78 inline size_t obj_size(HeapWord* addr) const;
79
80 // Apply live_closure to each live object that lies completely within the
81 // range [live_range_beg, live_range_end). This is used to iterate over the
82 // compacted region of the heap. Return values:
83 //
84 // incomplete The iteration is not complete. The last object that
85 // begins in the range does not end in the range;
86 // closure->source() is set to the start of that object.
87 //
88 // complete The iteration is complete. All objects in the range
89 // were processed and the closure is not full;
90 // closure->source() is set one past the end of the range.
91 //
92 // full The closure is full; closure->source() is set to one
93 // past the end of the last object processed.
94 //
95 // would_overflow The next object in the range would overflow the closure;
96 // closure->source() is set to the start of that object.
97 IterationStatus iterate(ParMarkBitMapClosure* live_closure,
98 idx_t range_beg, idx_t range_end) const;
99 inline IterationStatus iterate(ParMarkBitMapClosure* live_closure,
100 HeapWord* range_beg,
101 HeapWord* range_end) const;
102
103 // Apply live closure as above and additionally apply dead_closure to all dead
104 // space in the range [range_beg, dead_range_end). Note that dead_range_end
105 // must be >= range_end. This is used to iterate over the dense prefix.
106 //
107 // This method assumes that if the first bit in the range (range_beg) is not
108 // marked, then dead space begins at that point and the dead_closure is
109 // applied. Thus callers must ensure that range_beg is not in the middle of a
110 // live object.
111 IterationStatus iterate(ParMarkBitMapClosure* live_closure,
112 ParMarkBitMapClosure* dead_closure,
113 idx_t range_beg, idx_t range_end,
114 idx_t dead_range_end) const;
115 inline IterationStatus iterate(ParMarkBitMapClosure* live_closure,
116 ParMarkBitMapClosure* dead_closure,
117 HeapWord* range_beg,
118 HeapWord* range_end,
119 HeapWord* dead_range_end) const;
120
121 // Return the number of live words in the range [beg_addr, end_obj) due to
122 // objects that start in the range. If a live object extends onto the range,
123 // the caller must detect and account for any live words due to that object.
124 // If a live object extends beyond the end of the range, only the words within
125 // the range are included in the result. The end of the range must be a live object,
126 // which is the case when updating pointers. This allows a branch to be removed
127 // from inside the loop.
128 size_t live_words_in_range(ParCompactionManager* cm, HeapWord* beg_addr, oop end_obj) const;
129
130 inline HeapWord* region_start() const;
131 inline HeapWord* region_end() const;
132 inline size_t region_size() const;
133 inline size_t size() const;
134
135 size_t reserved_byte_size() const { return _reserved_byte_size; }
136
137 // Convert a heap address to/from a bit index.
138 inline idx_t addr_to_bit(HeapWord* addr) const;
139 inline HeapWord* bit_to_addr(idx_t bit) const;
140
141 // Return the bit index of the first marked object that begins (or ends,
142 // respectively) in the range [beg, end). If no object is found, return end.
143 inline idx_t find_obj_beg(idx_t beg, idx_t end) const;
144 inline idx_t find_obj_end(idx_t beg, idx_t end) const;
145
146 inline HeapWord* find_obj_beg(HeapWord* beg, HeapWord* end) const;
147 inline HeapWord* find_obj_end(HeapWord* beg, HeapWord* end) const;
148
149 // Clear a range of bits or the entire bitmap (both begin and end bits are
150 // cleared).
151 inline void clear_range(idx_t beg, idx_t end);
152
153 // Return the number of bits required to represent the specified number of
154 // HeapWords, or the specified region.
155 static inline idx_t bits_required(size_t words);
156 static inline idx_t bits_required(MemRegion covered_region);
157
158 void print_on_error(outputStream* st) const {
159 st->print_cr("Marking Bits: (ParMarkBitMap*) " PTR_FORMAT, p2i(this));
160 _beg_bits.print_on_error(st, " Begin Bits: ");
161 _end_bits.print_on_error(st, " End Bits: ");
162 }
163
164#ifdef ASSERT
165 void verify_clear() const;
166 inline void verify_bit(idx_t bit) const;
167 inline void verify_addr(HeapWord* addr) const;
168#endif // #ifdef ASSERT
169
170private:
171 size_t live_words_in_range_helper(HeapWord* beg_addr, oop end_obj) const;
172
173 bool is_live_words_in_range_in_cache(ParCompactionManager* cm, HeapWord* beg_addr) const;
174 size_t live_words_in_range_use_cache(ParCompactionManager* cm, HeapWord* beg_addr, oop end_obj) const;
175 void update_live_words_in_range_cache(ParCompactionManager* cm, HeapWord* beg_addr, oop end_obj, size_t result) const;
176
177 // Each bit in the bitmap represents one unit of 'object granularity.' Objects
178 // are double-word aligned in 32-bit VMs, but not in 64-bit VMs, so the 32-bit
179 // granularity is 2, 64-bit is 1.
180 static inline size_t obj_granularity() { return size_t(MinObjAlignment); }
181 static inline int obj_granularity_shift() { return LogMinObjAlignment; }
182
183 HeapWord* _region_start;
184 size_t _region_size;
185 BitMapView _beg_bits;
186 BitMapView _end_bits;
187 PSVirtualSpace* _virtual_space;
188 size_t _reserved_byte_size;
189};
190
191#endif // SHARE_GC_PARALLEL_PARMARKBITMAP_HPP
192