Mercurial > hg > graal-jvmci-8
annotate src/share/vm/gc_implementation/g1/g1BlockOffsetTable.hpp @ 6750:859cd1a76f8a
7197906: BlockOffsetArray::power_to_cards_back() needs to handle > 32 bit shifts
Reviewed-by: brutisso, johnc, ysr
Contributed-by: Hal Mo <kungu.mjh@taobao.com>
author | brutisso |
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date | Thu, 13 Sep 2012 21:20:26 +0200 |
parents | f99a36499b8c |
children | 2fc0334f613a |
rev | line source |
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342 | 1 /* |
6610 | 2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved. |
342 | 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 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
342 | 22 * |
23 */ | |
24 | |
1972 | 25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1BLOCKOFFSETTABLE_HPP |
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1BLOCKOFFSETTABLE_HPP | |
27 | |
28 #include "memory/memRegion.hpp" | |
29 #include "runtime/virtualspace.hpp" | |
30 #include "utilities/globalDefinitions.hpp" | |
31 | |
342 | 32 // The CollectedHeap type requires subtypes to implement a method |
33 // "block_start". For some subtypes, notably generational | |
34 // systems using card-table-based write barriers, the efficiency of this | |
35 // operation may be important. Implementations of the "BlockOffsetArray" | |
36 // class may be useful in providing such efficient implementations. | |
37 // | |
38 // While generally mirroring the structure of the BOT for GenCollectedHeap, | |
39 // the following types are tailored more towards G1's uses; these should, | |
40 // however, be merged back into a common BOT to avoid code duplication | |
41 // and reduce maintenance overhead. | |
42 // | |
43 // G1BlockOffsetTable (abstract) | |
44 // -- G1BlockOffsetArray (uses G1BlockOffsetSharedArray) | |
45 // -- G1BlockOffsetArrayContigSpace | |
46 // | |
47 // A main impediment to the consolidation of this code might be the | |
48 // effect of making some of the block_start*() calls non-const as | |
49 // below. Whether that might adversely affect performance optimizations | |
50 // that compilers might normally perform in the case of non-G1 | |
51 // collectors needs to be carefully investigated prior to any such | |
52 // consolidation. | |
53 | |
54 // Forward declarations | |
55 class ContiguousSpace; | |
56 class G1BlockOffsetSharedArray; | |
57 | |
58 class G1BlockOffsetTable VALUE_OBJ_CLASS_SPEC { | |
59 friend class VMStructs; | |
60 protected: | |
61 // These members describe the region covered by the table. | |
62 | |
63 // The space this table is covering. | |
64 HeapWord* _bottom; // == reserved.start | |
65 HeapWord* _end; // End of currently allocated region. | |
66 | |
67 public: | |
68 // Initialize the table to cover the given space. | |
69 // The contents of the initial table are undefined. | |
70 G1BlockOffsetTable(HeapWord* bottom, HeapWord* end) : | |
71 _bottom(bottom), _end(end) | |
72 { | |
73 assert(_bottom <= _end, "arguments out of order"); | |
74 } | |
75 | |
76 // Note that the committed size of the covered space may have changed, | |
77 // so the table size might also wish to change. | |
78 virtual void resize(size_t new_word_size) = 0; | |
79 | |
80 virtual void set_bottom(HeapWord* new_bottom) { | |
81 assert(new_bottom <= _end, "new_bottom > _end"); | |
82 _bottom = new_bottom; | |
83 resize(pointer_delta(_end, _bottom)); | |
84 } | |
85 | |
86 // Requires "addr" to be contained by a block, and returns the address of | |
87 // the start of that block. (May have side effects, namely updating of | |
88 // shared array entries that "point" too far backwards. This can occur, | |
89 // for example, when LAB allocation is used in a space covered by the | |
90 // table.) | |
91 virtual HeapWord* block_start_unsafe(const void* addr) = 0; | |
92 // Same as above, but does not have any of the possible side effects | |
93 // discussed above. | |
94 virtual HeapWord* block_start_unsafe_const(const void* addr) const = 0; | |
95 | |
96 // Returns the address of the start of the block containing "addr", or | |
97 // else "null" if it is covered by no block. (May have side effects, | |
98 // namely updating of shared array entries that "point" too far | |
99 // backwards. This can occur, for example, when lab allocation is used | |
100 // in a space covered by the table.) | |
101 inline HeapWord* block_start(const void* addr); | |
102 // Same as above, but does not have any of the possible side effects | |
103 // discussed above. | |
104 inline HeapWord* block_start_const(const void* addr) const; | |
105 }; | |
106 | |
107 // This implementation of "G1BlockOffsetTable" divides the covered region | |
108 // into "N"-word subregions (where "N" = 2^"LogN". An array with an entry | |
109 // for each such subregion indicates how far back one must go to find the | |
110 // start of the chunk that includes the first word of the subregion. | |
111 // | |
112 // Each BlockOffsetArray is owned by a Space. However, the actual array | |
113 // may be shared by several BlockOffsetArrays; this is useful | |
114 // when a single resizable area (such as a generation) is divided up into | |
115 // several spaces in which contiguous allocation takes place, | |
116 // such as, for example, in G1 or in the train generation.) | |
117 | |
118 // Here is the shared array type. | |
119 | |
6197 | 120 class G1BlockOffsetSharedArray: public CHeapObj<mtGC> { |
342 | 121 friend class G1BlockOffsetArray; |
122 friend class G1BlockOffsetArrayContigSpace; | |
123 friend class VMStructs; | |
124 | |
125 private: | |
126 // The reserved region covered by the shared array. | |
127 MemRegion _reserved; | |
128 | |
129 // End of the current committed region. | |
130 HeapWord* _end; | |
131 | |
132 // Array for keeping offsets for retrieving object start fast given an | |
133 // address. | |
134 VirtualSpace _vs; | |
135 u_char* _offset_array; // byte array keeping backwards offsets | |
136 | |
137 // Bounds checking accessors: | |
138 // For performance these have to devolve to array accesses in product builds. | |
139 u_char offset_array(size_t index) const { | |
140 assert(index < _vs.committed_size(), "index out of range"); | |
141 return _offset_array[index]; | |
142 } | |
143 | |
144 void set_offset_array(size_t index, u_char offset) { | |
145 assert(index < _vs.committed_size(), "index out of range"); | |
146 assert(offset <= N_words, "offset too large"); | |
147 _offset_array[index] = offset; | |
148 } | |
149 | |
150 void set_offset_array(size_t index, HeapWord* high, HeapWord* low) { | |
151 assert(index < _vs.committed_size(), "index out of range"); | |
152 assert(high >= low, "addresses out of order"); | |
153 assert(pointer_delta(high, low) <= N_words, "offset too large"); | |
154 _offset_array[index] = (u_char) pointer_delta(high, low); | |
155 } | |
156 | |
157 void set_offset_array(HeapWord* left, HeapWord* right, u_char offset) { | |
158 assert(index_for(right - 1) < _vs.committed_size(), | |
159 "right address out of range"); | |
160 assert(left < right, "Heap addresses out of order"); | |
161 size_t num_cards = pointer_delta(right, left) >> LogN_words; | |
6610 | 162 if (UseMemSetInBOT) { |
163 memset(&_offset_array[index_for(left)], offset, num_cards); | |
164 } else { | |
165 size_t i = index_for(left); | |
166 const size_t end = i + num_cards; | |
167 for (; i < end; i++) { | |
168 _offset_array[i] = offset; | |
169 } | |
170 } | |
342 | 171 } |
172 | |
173 void set_offset_array(size_t left, size_t right, u_char offset) { | |
174 assert(right < _vs.committed_size(), "right address out of range"); | |
6610 | 175 assert(left <= right, "indexes out of order"); |
342 | 176 size_t num_cards = right - left + 1; |
6610 | 177 if (UseMemSetInBOT) { |
178 memset(&_offset_array[left], offset, num_cards); | |
179 } else { | |
180 size_t i = left; | |
181 const size_t end = i + num_cards; | |
182 for (; i < end; i++) { | |
183 _offset_array[i] = offset; | |
184 } | |
185 } | |
342 | 186 } |
187 | |
188 void check_offset_array(size_t index, HeapWord* high, HeapWord* low) const { | |
189 assert(index < _vs.committed_size(), "index out of range"); | |
190 assert(high >= low, "addresses out of order"); | |
191 assert(pointer_delta(high, low) <= N_words, "offset too large"); | |
192 assert(_offset_array[index] == pointer_delta(high, low), | |
193 "Wrong offset"); | |
194 } | |
195 | |
196 bool is_card_boundary(HeapWord* p) const; | |
197 | |
198 // Return the number of slots needed for an offset array | |
199 // that covers mem_region_words words. | |
200 // We always add an extra slot because if an object | |
201 // ends on a card boundary we put a 0 in the next | |
202 // offset array slot, so we want that slot always | |
203 // to be reserved. | |
204 | |
205 size_t compute_size(size_t mem_region_words) { | |
206 size_t number_of_slots = (mem_region_words / N_words) + 1; | |
207 return ReservedSpace::page_align_size_up(number_of_slots); | |
208 } | |
209 | |
210 public: | |
211 enum SomePublicConstants { | |
212 LogN = 9, | |
213 LogN_words = LogN - LogHeapWordSize, | |
214 N_bytes = 1 << LogN, | |
215 N_words = 1 << LogN_words | |
216 }; | |
217 | |
218 // Initialize the table to cover from "base" to (at least) | |
219 // "base + init_word_size". In the future, the table may be expanded | |
220 // (see "resize" below) up to the size of "_reserved" (which must be at | |
221 // least "init_word_size".) The contents of the initial table are | |
222 // undefined; it is the responsibility of the constituent | |
223 // G1BlockOffsetTable(s) to initialize cards. | |
224 G1BlockOffsetSharedArray(MemRegion reserved, size_t init_word_size); | |
225 | |
226 // Notes a change in the committed size of the region covered by the | |
227 // table. The "new_word_size" may not be larger than the size of the | |
228 // reserved region this table covers. | |
229 void resize(size_t new_word_size); | |
230 | |
231 void set_bottom(HeapWord* new_bottom); | |
232 | |
233 // Updates all the BlockOffsetArray's sharing this shared array to | |
234 // reflect the current "top"'s of their spaces. | |
235 void update_offset_arrays(); | |
236 | |
237 // Return the appropriate index into "_offset_array" for "p". | |
238 inline size_t index_for(const void* p) const; | |
239 | |
240 // Return the address indicating the start of the region corresponding to | |
241 // "index" in "_offset_array". | |
242 inline HeapWord* address_for_index(size_t index) const; | |
243 }; | |
244 | |
245 // And here is the G1BlockOffsetTable subtype that uses the array. | |
246 | |
247 class G1BlockOffsetArray: public G1BlockOffsetTable { | |
248 friend class G1BlockOffsetSharedArray; | |
249 friend class G1BlockOffsetArrayContigSpace; | |
250 friend class VMStructs; | |
251 private: | |
252 enum SomePrivateConstants { | |
253 N_words = G1BlockOffsetSharedArray::N_words, | |
254 LogN = G1BlockOffsetSharedArray::LogN | |
255 }; | |
256 | |
257 // The following enums are used by do_block_helper | |
258 enum Action { | |
259 Action_single, // BOT records a single block (see single_block()) | |
260 Action_mark, // BOT marks the start of a block (see mark_block()) | |
261 Action_check // Check that BOT records block correctly | |
262 // (see verify_single_block()). | |
263 }; | |
264 | |
265 // This is the array, which can be shared by several BlockOffsetArray's | |
266 // servicing different | |
267 G1BlockOffsetSharedArray* _array; | |
268 | |
269 // The space that owns this subregion. | |
270 Space* _sp; | |
271 | |
272 // If "_sp" is a contiguous space, the field below is the view of "_sp" | |
273 // as a contiguous space, else NULL. | |
274 ContiguousSpace* _csp; | |
275 | |
276 // If true, array entries are initialized to 0; otherwise, they are | |
277 // initialized to point backwards to the beginning of the covered region. | |
278 bool _init_to_zero; | |
279 | |
280 // The portion [_unallocated_block, _sp.end()) of the space that | |
281 // is a single block known not to contain any objects. | |
282 // NOTE: See BlockOffsetArrayUseUnallocatedBlock flag. | |
283 HeapWord* _unallocated_block; | |
284 | |
285 // Sets the entries | |
286 // corresponding to the cards starting at "start" and ending at "end" | |
287 // to point back to the card before "start": the interval [start, end) | |
288 // is right-open. | |
289 void set_remainder_to_point_to_start(HeapWord* start, HeapWord* end); | |
290 // Same as above, except that the args here are a card _index_ interval | |
291 // that is closed: [start_index, end_index] | |
292 void set_remainder_to_point_to_start_incl(size_t start, size_t end); | |
293 | |
294 // A helper function for BOT adjustment/verification work | |
295 void do_block_internal(HeapWord* blk_start, HeapWord* blk_end, Action action); | |
296 | |
297 protected: | |
298 | |
299 ContiguousSpace* csp() const { return _csp; } | |
300 | |
301 // Returns the address of a block whose start is at most "addr". | |
302 // If "has_max_index" is true, "assumes "max_index" is the last valid one | |
303 // in the array. | |
304 inline HeapWord* block_at_or_preceding(const void* addr, | |
305 bool has_max_index, | |
306 size_t max_index) const; | |
307 | |
308 // "q" is a block boundary that is <= "addr"; "n" is the address of the | |
309 // next block (or the end of the space.) Return the address of the | |
310 // beginning of the block that contains "addr". Does so without side | |
311 // effects (see, e.g., spec of block_start.) | |
312 inline HeapWord* | |
313 forward_to_block_containing_addr_const(HeapWord* q, HeapWord* n, | |
314 const void* addr) const; | |
315 | |
316 // "q" is a block boundary that is <= "addr"; return the address of the | |
317 // beginning of the block that contains "addr". May have side effects | |
318 // on "this", by updating imprecise entries. | |
319 inline HeapWord* forward_to_block_containing_addr(HeapWord* q, | |
320 const void* addr); | |
321 | |
322 // "q" is a block boundary that is <= "addr"; "n" is the address of the | |
323 // next block (or the end of the space.) Return the address of the | |
324 // beginning of the block that contains "addr". May have side effects | |
325 // on "this", by updating imprecise entries. | |
326 HeapWord* forward_to_block_containing_addr_slow(HeapWord* q, | |
327 HeapWord* n, | |
328 const void* addr); | |
329 | |
330 // Requires that "*threshold_" be the first array entry boundary at or | |
331 // above "blk_start", and that "*index_" be the corresponding array | |
332 // index. If the block starts at or crosses "*threshold_", records | |
333 // "blk_start" as the appropriate block start for the array index | |
334 // starting at "*threshold_", and for any other indices crossed by the | |
335 // block. Updates "*threshold_" and "*index_" to correspond to the first | |
336 // index after the block end. | |
337 void alloc_block_work2(HeapWord** threshold_, size_t* index_, | |
338 HeapWord* blk_start, HeapWord* blk_end); | |
339 | |
340 public: | |
341 // The space may not have it's bottom and top set yet, which is why the | |
342 // region is passed as a parameter. If "init_to_zero" is true, the | |
343 // elements of the array are initialized to zero. Otherwise, they are | |
344 // initialized to point backwards to the beginning. | |
345 G1BlockOffsetArray(G1BlockOffsetSharedArray* array, MemRegion mr, | |
346 bool init_to_zero); | |
347 | |
348 // Note: this ought to be part of the constructor, but that would require | |
349 // "this" to be passed as a parameter to a member constructor for | |
350 // the containing concrete subtype of Space. | |
351 // This would be legal C++, but MS VC++ doesn't allow it. | |
352 void set_space(Space* sp); | |
353 | |
354 // Resets the covered region to the given "mr". | |
355 void set_region(MemRegion mr); | |
356 | |
357 // Resets the covered region to one with the same _bottom as before but | |
358 // the "new_word_size". | |
359 void resize(size_t new_word_size); | |
360 | |
361 // These must be guaranteed to work properly (i.e., do nothing) | |
362 // when "blk_start" ("blk" for second version) is "NULL". | |
363 virtual void alloc_block(HeapWord* blk_start, HeapWord* blk_end); | |
364 virtual void alloc_block(HeapWord* blk, size_t size) { | |
365 alloc_block(blk, blk + size); | |
366 } | |
367 | |
368 // The following methods are useful and optimized for a | |
369 // general, non-contiguous space. | |
370 | |
371 // Given a block [blk_start, blk_start + full_blk_size), and | |
372 // a left_blk_size < full_blk_size, adjust the BOT to show two | |
373 // blocks [blk_start, blk_start + left_blk_size) and | |
374 // [blk_start + left_blk_size, blk_start + full_blk_size). | |
375 // It is assumed (and verified in the non-product VM) that the | |
376 // BOT was correct for the original block. | |
377 void split_block(HeapWord* blk_start, size_t full_blk_size, | |
378 size_t left_blk_size); | |
379 | |
380 // Adjust the BOT to show that it has a single block in the | |
381 // range [blk_start, blk_start + size). All necessary BOT | |
382 // cards are adjusted, but _unallocated_block isn't. | |
383 void single_block(HeapWord* blk_start, HeapWord* blk_end); | |
384 void single_block(HeapWord* blk, size_t size) { | |
385 single_block(blk, blk + size); | |
386 } | |
387 | |
388 // Adjust BOT to show that it has a block in the range | |
389 // [blk_start, blk_start + size). Only the first card | |
390 // of BOT is touched. It is assumed (and verified in the | |
391 // non-product VM) that the remaining cards of the block | |
392 // are correct. | |
393 void mark_block(HeapWord* blk_start, HeapWord* blk_end); | |
394 void mark_block(HeapWord* blk, size_t size) { | |
395 mark_block(blk, blk + size); | |
396 } | |
397 | |
398 // Adjust _unallocated_block to indicate that a particular | |
399 // block has been newly allocated or freed. It is assumed (and | |
400 // verified in the non-product VM) that the BOT is correct for | |
401 // the given block. | |
402 inline void allocated(HeapWord* blk_start, HeapWord* blk_end) { | |
403 // Verify that the BOT shows [blk, blk + blk_size) to be one block. | |
404 verify_single_block(blk_start, blk_end); | |
405 if (BlockOffsetArrayUseUnallocatedBlock) { | |
406 _unallocated_block = MAX2(_unallocated_block, blk_end); | |
407 } | |
408 } | |
409 | |
410 inline void allocated(HeapWord* blk, size_t size) { | |
411 allocated(blk, blk + size); | |
412 } | |
413 | |
414 inline void freed(HeapWord* blk_start, HeapWord* blk_end); | |
415 | |
416 inline void freed(HeapWord* blk, size_t size); | |
417 | |
418 virtual HeapWord* block_start_unsafe(const void* addr); | |
419 virtual HeapWord* block_start_unsafe_const(const void* addr) const; | |
420 | |
421 // Requires "addr" to be the start of a card and returns the | |
422 // start of the block that contains the given address. | |
423 HeapWord* block_start_careful(const void* addr) const; | |
424 | |
425 // If true, initialize array slots with no allocated blocks to zero. | |
426 // Otherwise, make them point back to the front. | |
427 bool init_to_zero() { return _init_to_zero; } | |
428 | |
429 // Verification & debugging - ensure that the offset table reflects the fact | |
430 // that the block [blk_start, blk_end) or [blk, blk + size) is a | |
431 // single block of storage. NOTE: can;t const this because of | |
432 // call to non-const do_block_internal() below. | |
433 inline void verify_single_block(HeapWord* blk_start, HeapWord* blk_end) { | |
434 if (VerifyBlockOffsetArray) { | |
435 do_block_internal(blk_start, blk_end, Action_check); | |
436 } | |
437 } | |
438 | |
439 inline void verify_single_block(HeapWord* blk, size_t size) { | |
440 verify_single_block(blk, blk + size); | |
441 } | |
442 | |
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443 // Used by region verification. Checks that the contents of the |
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444 // BOT reflect that there's a single object that spans the address |
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445 // range [obj_start, obj_start + word_size); returns true if this is |
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446 // the case, returns false if it's not. |
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447 bool verify_for_object(HeapWord* obj_start, size_t word_size) const; |
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448 |
342 | 449 // Verify that the given block is before _unallocated_block |
450 inline void verify_not_unallocated(HeapWord* blk_start, | |
451 HeapWord* blk_end) const { | |
452 if (BlockOffsetArrayUseUnallocatedBlock) { | |
453 assert(blk_start < blk_end, "Block inconsistency?"); | |
454 assert(blk_end <= _unallocated_block, "_unallocated_block problem"); | |
455 } | |
456 } | |
457 | |
458 inline void verify_not_unallocated(HeapWord* blk, size_t size) const { | |
459 verify_not_unallocated(blk, blk + size); | |
460 } | |
461 | |
462 void check_all_cards(size_t left_card, size_t right_card) const; | |
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463 |
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464 virtual void print_on(outputStream* out) PRODUCT_RETURN; |
342 | 465 }; |
466 | |
467 // A subtype of BlockOffsetArray that takes advantage of the fact | |
468 // that its underlying space is a ContiguousSpace, so that its "active" | |
469 // region can be more efficiently tracked (than for a non-contiguous space). | |
470 class G1BlockOffsetArrayContigSpace: public G1BlockOffsetArray { | |
471 friend class VMStructs; | |
472 | |
473 // allocation boundary at which offset array must be updated | |
474 HeapWord* _next_offset_threshold; | |
475 size_t _next_offset_index; // index corresponding to that boundary | |
476 | |
477 // Work function to be called when allocation start crosses the next | |
478 // threshold in the contig space. | |
479 void alloc_block_work1(HeapWord* blk_start, HeapWord* blk_end) { | |
480 alloc_block_work2(&_next_offset_threshold, &_next_offset_index, | |
481 blk_start, blk_end); | |
482 } | |
483 | |
484 | |
485 public: | |
486 G1BlockOffsetArrayContigSpace(G1BlockOffsetSharedArray* array, MemRegion mr); | |
487 | |
488 // Initialize the threshold to reflect the first boundary after the | |
489 // bottom of the covered region. | |
490 HeapWord* initialize_threshold(); | |
491 | |
492 // Zero out the entry for _bottom (offset will be zero). | |
493 void zero_bottom_entry(); | |
494 | |
495 // Return the next threshold, the point at which the table should be | |
496 // updated. | |
497 HeapWord* threshold() const { return _next_offset_threshold; } | |
498 | |
499 // These must be guaranteed to work properly (i.e., do nothing) | |
500 // when "blk_start" ("blk" for second version) is "NULL". In this | |
501 // implementation, that's true because NULL is represented as 0, and thus | |
502 // never exceeds the "_next_offset_threshold". | |
503 void alloc_block(HeapWord* blk_start, HeapWord* blk_end) { | |
504 if (blk_end > _next_offset_threshold) | |
505 alloc_block_work1(blk_start, blk_end); | |
506 } | |
507 void alloc_block(HeapWord* blk, size_t size) { | |
508 alloc_block(blk, blk+size); | |
509 } | |
510 | |
511 HeapWord* block_start_unsafe(const void* addr); | |
512 HeapWord* block_start_unsafe_const(const void* addr) const; | |
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513 |
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514 void set_for_starts_humongous(HeapWord* new_top); |
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515 |
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516 virtual void print_on(outputStream* out) PRODUCT_RETURN; |
342 | 517 }; |
1972 | 518 |
519 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1BLOCKOFFSETTABLE_HPP |