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_G1BLOCKOFFSETTABLE_HPP
26 #define SHARE_VM_GC_G1_G1BLOCKOFFSETTABLE_HPP
27
28 #include "gc/g1/g1RegionToSpaceMapper.hpp"
29 #include "memory/memRegion.hpp"
30 #include "memory/virtualspace.hpp"
31 #include "utilities/globalDefinitions.hpp"
32
33 // Forward declarations
34 class G1BlockOffsetTable;
35 class G1ContiguousSpace;
36
37 // This implementation of "G1BlockOffsetTable" divides the covered region
38 // into "N"-word subregions (where "N" = 2^"LogN". An array with an entry
39 // for each such subregion indicates how far back one must go to find the
40 // start of the chunk that includes the first word of the subregion.
41 //
42 // Each G1BlockOffsetTablePart is owned by a G1ContiguousSpace.
43
44 class G1BlockOffsetTable: public CHeapObj<mtGC> {
45 friend class G1BlockOffsetTablePart;
46 friend class VMStructs;
47
48 private:
49 // The reserved region covered by the table.
50 MemRegion _reserved;
51
52 // Array for keeping offsets for retrieving object start fast given an
53 // address.
54 u_char* _offset_array; // byte array keeping backwards offsets
55
56 void check_offset(size_t offset, const char* msg) const {
57 assert(offset <= N_words,
58 "%s - offset: " SIZE_FORMAT ", N_words: %u",
59 msg, offset, (uint)N_words);
60 }
61
62 // Bounds checking accessors:
63 // For performance these have to devolve to array accesses in product builds.
64 inline u_char offset_array(size_t index) const;
65
66 void set_offset_array_raw(size_t index, u_char offset) {
67 _offset_array[index] = offset;
68 }
69
70 inline void set_offset_array(size_t index, u_char offset);
71
72 inline void set_offset_array(size_t index, HeapWord* high, HeapWord* low);
73
74 inline void set_offset_array(size_t left, size_t right, u_char offset);
75
76 bool is_card_boundary(HeapWord* p) const;
77
78 void check_index(size_t index, const char* msg) const NOT_DEBUG_RETURN;
79
80 public:
81
82 // Return the number of slots needed for an offset array
83 // that covers mem_region_words words.
84 static size_t compute_size(size_t mem_region_words) {
85 size_t number_of_slots = (mem_region_words / N_words);
86 return ReservedSpace::allocation_align_size_up(number_of_slots);
87 }
88
89 // Returns how many bytes of the heap a single byte of the BOT corresponds to.
90 static size_t heap_map_factor() {
91 return N_bytes;
92 }
93
94 enum SomePublicConstants {
95 LogN = 9,
96 LogN_words = LogN - LogHeapWordSize,
97 N_bytes = 1 << LogN,
98 N_words = 1 << LogN_words
99 };
100
101 // Initialize the Block Offset Table to cover the memory region passed
102 // in the heap parameter.
103 G1BlockOffsetTable(MemRegion heap, G1RegionToSpaceMapper* storage);
104
105 // Return the appropriate index into "_offset_array" for "p".
106 inline size_t index_for(const void* p) const;
107 inline size_t index_for_raw(const void* p) const;
108
109 // Return the address indicating the start of the region corresponding to
110 // "index" in "_offset_array".
111 inline HeapWord* address_for_index(size_t index) const;
112 // Variant of address_for_index that does not check the index for validity.
113 inline HeapWord* address_for_index_raw(size_t index) const {
114 return _reserved.start() + (index << LogN_words);
115 }
116 };
117
118 class G1BlockOffsetTablePart VALUE_OBJ_CLASS_SPEC {
119 friend class G1BlockOffsetTable;
120 friend class VMStructs;
121 private:
122 enum SomePrivateConstants {
123 N_words = G1BlockOffsetTable::N_words,
124 LogN = G1BlockOffsetTable::LogN
125 };
126
127 // allocation boundary at which offset array must be updated
128 HeapWord* _next_offset_threshold;
129 size_t _next_offset_index; // index corresponding to that boundary
130
131 // This is the global BlockOffsetTable.
132 G1BlockOffsetTable* _bot;
133
134 // The space that owns this subregion.
135 G1ContiguousSpace* _space;
136
137 // Sets the entries
138 // corresponding to the cards starting at "start" and ending at "end"
139 // to point back to the card before "start": the interval [start, end)
140 // is right-open.
141 void set_remainder_to_point_to_start(HeapWord* start, HeapWord* end);
142 // Same as above, except that the args here are a card _index_ interval
143 // that is closed: [start_index, end_index]
144 void set_remainder_to_point_to_start_incl(size_t start, size_t end);
145
146 // Zero out the entry for _bottom (offset will be zero). Does not check for availability of the
|
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_G1BLOCKOFFSETTABLE_HPP
26 #define SHARE_VM_GC_G1_G1BLOCKOFFSETTABLE_HPP
27
28 #include "gc/g1/g1RegionToSpaceMapper.hpp"
29 #include "gc/shared/blockOffsetTable.hpp"
30 #include "memory/memRegion.hpp"
31 #include "memory/virtualspace.hpp"
32 #include "utilities/globalDefinitions.hpp"
33
34 // Forward declarations
35 class G1BlockOffsetTable;
36 class G1ContiguousSpace;
37
38 // This implementation of "G1BlockOffsetTable" divides the covered region
39 // into "N"-word subregions (where "N" = 2^"LogN". An array with an entry
40 // for each such subregion indicates how far back one must go to find the
41 // start of the chunk that includes the first word of the subregion.
42 //
43 // Each G1BlockOffsetTablePart is owned by a G1ContiguousSpace.
44
45 class G1BlockOffsetTable: public CHeapObj<mtGC> {
46 friend class G1BlockOffsetTablePart;
47 friend class VMStructs;
48
49 private:
50 // The reserved region covered by the table.
51 MemRegion _reserved;
52
53 // Array for keeping offsets for retrieving object start fast given an
54 // address.
55 u_char* _offset_array; // byte array keeping backwards offsets
56
57 void check_offset(size_t offset, const char* msg) const {
58 assert(offset <= BOTConstants::N_words,
59 "%s - offset: " SIZE_FORMAT ", N_words: %u",
60 msg, offset, BOTConstants::N_words);
61 }
62
63 // Bounds checking accessors:
64 // For performance these have to devolve to array accesses in product builds.
65 inline u_char offset_array(size_t index) const;
66
67 void set_offset_array_raw(size_t index, u_char offset) {
68 _offset_array[index] = offset;
69 }
70
71 inline void set_offset_array(size_t index, u_char offset);
72
73 inline void set_offset_array(size_t index, HeapWord* high, HeapWord* low);
74
75 inline void set_offset_array(size_t left, size_t right, u_char offset);
76
77 bool is_card_boundary(HeapWord* p) const;
78
79 void check_index(size_t index, const char* msg) const NOT_DEBUG_RETURN;
80
81 public:
82
83 // Return the number of slots needed for an offset array
84 // that covers mem_region_words words.
85 static size_t compute_size(size_t mem_region_words) {
86 size_t number_of_slots = (mem_region_words / BOTConstants::N_words);
87 return ReservedSpace::allocation_align_size_up(number_of_slots);
88 }
89
90 // Returns how many bytes of the heap a single byte of the BOT corresponds to.
91 static size_t heap_map_factor() {
92 return BOTConstants::N_bytes;
93 }
94
95 // Initialize the Block Offset Table to cover the memory region passed
96 // in the heap parameter.
97 G1BlockOffsetTable(MemRegion heap, G1RegionToSpaceMapper* storage);
98
99 // Return the appropriate index into "_offset_array" for "p".
100 inline size_t index_for(const void* p) const;
101 inline size_t index_for_raw(const void* p) const;
102
103 // Return the address indicating the start of the region corresponding to
104 // "index" in "_offset_array".
105 inline HeapWord* address_for_index(size_t index) const;
106 // Variant of address_for_index that does not check the index for validity.
107 inline HeapWord* address_for_index_raw(size_t index) const {
108 return _reserved.start() + (index << BOTConstants::LogN_words);
109 }
110 };
111
112 class G1BlockOffsetTablePart VALUE_OBJ_CLASS_SPEC {
113 friend class G1BlockOffsetTable;
114 friend class VMStructs;
115 private:
116 // allocation boundary at which offset array must be updated
117 HeapWord* _next_offset_threshold;
118 size_t _next_offset_index; // index corresponding to that boundary
119
120 // This is the global BlockOffsetTable.
121 G1BlockOffsetTable* _bot;
122
123 // The space that owns this subregion.
124 G1ContiguousSpace* _space;
125
126 // Sets the entries
127 // corresponding to the cards starting at "start" and ending at "end"
128 // to point back to the card before "start": the interval [start, end)
129 // is right-open.
130 void set_remainder_to_point_to_start(HeapWord* start, HeapWord* end);
131 // Same as above, except that the args here are a card _index_ interval
132 // that is closed: [start_index, end_index]
133 void set_remainder_to_point_to_start_incl(size_t start, size_t end);
134
135 // Zero out the entry for _bottom (offset will be zero). Does not check for availability of the
|