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_GC_G1_G1BLOCKOFFSETTABLE_HPP
26 #define SHARE_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 volatile 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:
103 // Variant of address_for_index that does not check the index for validity.
104 inline HeapWord* address_for_index_raw(size_t index) const {
105 return _reserved.start() + (index << BOTConstants::LogN_words);
106 }
107 };
108
109 class G1BlockOffsetTablePart {
110 friend class G1BlockOffsetTable;
111 friend class VMStructs;
112 private:
113 // allocation boundary at which offset array must be updated
114 HeapWord* _next_offset_threshold;
115 size_t _next_offset_index; // index corresponding to that boundary
116
117 // Indicates if an object can span into this G1BlockOffsetTablePart.
118 debug_only(bool _object_can_span;)
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
136 // memory first.
137 void zero_bottom_entry_raw();
138 // Variant of initialize_threshold that does not check for availability of the
139 // memory first.
140 HeapWord* initialize_threshold_raw();
141
142 inline size_t block_size(const HeapWord* p) const;
143
144 // Returns the address of a block whose start is at most "addr".
166 // beginning of the block that contains "addr". May have side effects
167 // on "this", by updating imprecise entries.
168 HeapWord* forward_to_block_containing_addr_slow(HeapWord* q,
169 HeapWord* n,
170 const void* addr);
171
172 // Requires that "*threshold_" be the first array entry boundary at or
173 // above "blk_start", and that "*index_" be the corresponding array
174 // index. If the block starts at or crosses "*threshold_", records
175 // "blk_start" as the appropriate block start for the array index
176 // starting at "*threshold_", and for any other indices crossed by the
177 // block. Updates "*threshold_" and "*index_" to correspond to the first
178 // index after the block end.
179 void alloc_block_work(HeapWord** threshold_, size_t* index_,
180 HeapWord* blk_start, HeapWord* blk_end);
181
182 void check_all_cards(size_t left_card, size_t right_card) const;
183
184 public:
185 // The elements of the array are initialized to zero.
186 G1BlockOffsetTablePart(G1BlockOffsetTable* array, G1ContiguousSpace* gsp);
187
188 void verify() const;
189
190 // Returns the address of the start of the block containing "addr", or
191 // else "null" if it is covered by no block. (May have side effects,
192 // namely updating of shared array entries that "point" too far
193 // backwards. This can occur, for example, when lab allocation is used
194 // in a space covered by the table.)
195 inline HeapWord* block_start(const void* addr);
196 // Same as above, but does not have any of the possible side effects
197 // discussed above.
198 inline HeapWord* block_start_const(const void* addr) const;
199
200 // Initialize the threshold to reflect the first boundary after the
201 // bottom of the covered region.
202 HeapWord* initialize_threshold();
203
204 void reset_bot() {
205 zero_bottom_entry_raw();
206 initialize_threshold_raw();
|
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_GC_G1_G1BLOCKOFFSETTABLE_HPP
26 #define SHARE_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 HeapRegion;
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 HeapRegion.
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 volatile 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:
103 // Variant of address_for_index that does not check the index for validity.
104 inline HeapWord* address_for_index_raw(size_t index) const {
105 return _reserved.start() + (index << BOTConstants::LogN_words);
106 }
107 };
108
109 class G1BlockOffsetTablePart {
110 friend class G1BlockOffsetTable;
111 friend class VMStructs;
112 private:
113 // allocation boundary at which offset array must be updated
114 HeapWord* _next_offset_threshold;
115 size_t _next_offset_index; // index corresponding to that boundary
116
117 // Indicates if an object can span into this G1BlockOffsetTablePart.
118 debug_only(bool _object_can_span;)
119
120 // This is the global BlockOffsetTable.
121 G1BlockOffsetTable* _bot;
122
123 // The region that owns this subregion.
124 HeapRegion* _hr;
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
136 // memory first.
137 void zero_bottom_entry_raw();
138 // Variant of initialize_threshold that does not check for availability of the
139 // memory first.
140 HeapWord* initialize_threshold_raw();
141
142 inline size_t block_size(const HeapWord* p) const;
143
144 // Returns the address of a block whose start is at most "addr".
166 // beginning of the block that contains "addr". May have side effects
167 // on "this", by updating imprecise entries.
168 HeapWord* forward_to_block_containing_addr_slow(HeapWord* q,
169 HeapWord* n,
170 const void* addr);
171
172 // Requires that "*threshold_" be the first array entry boundary at or
173 // above "blk_start", and that "*index_" be the corresponding array
174 // index. If the block starts at or crosses "*threshold_", records
175 // "blk_start" as the appropriate block start for the array index
176 // starting at "*threshold_", and for any other indices crossed by the
177 // block. Updates "*threshold_" and "*index_" to correspond to the first
178 // index after the block end.
179 void alloc_block_work(HeapWord** threshold_, size_t* index_,
180 HeapWord* blk_start, HeapWord* blk_end);
181
182 void check_all_cards(size_t left_card, size_t right_card) const;
183
184 public:
185 // The elements of the array are initialized to zero.
186 G1BlockOffsetTablePart(G1BlockOffsetTable* array, HeapRegion* hr);
187
188 void verify() const;
189
190 // Returns the address of the start of the block containing "addr", or
191 // else "null" if it is covered by no block. (May have side effects,
192 // namely updating of shared array entries that "point" too far
193 // backwards. This can occur, for example, when lab allocation is used
194 // in a space covered by the table.)
195 inline HeapWord* block_start(const void* addr);
196 // Same as above, but does not have any of the possible side effects
197 // discussed above.
198 inline HeapWord* block_start_const(const void* addr) const;
199
200 // Initialize the threshold to reflect the first boundary after the
201 // bottom of the covered region.
202 HeapWord* initialize_threshold();
203
204 void reset_bot() {
205 zero_bottom_entry_raw();
206 initialize_threshold_raw();
|