Mercurial > hg > graal-jvmci-8
annotate src/share/vm/gc_implementation/g1/g1BlockOffsetTable.hpp @ 1779:6eddcbe17c83
6981746: G1: SEGV with -XX:+TraceGen0Time
Summary: Pass correct value for length to NumberSeq constructor. Guard dereferences of "body_summary" pointer with a NULL check.
Reviewed-by: tonyp, ysr
author | johnc |
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date | Mon, 13 Sep 2010 10:00:24 -0700 |
parents | c18cbe5936b8 |
children | 72a161e62cc4 |
rev | line source |
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342 | 1 /* |
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2 * Copyright (c) 2001, 2007, 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 | |
25 // The CollectedHeap type requires subtypes to implement a method | |
26 // "block_start". For some subtypes, notably generational | |
27 // systems using card-table-based write barriers, the efficiency of this | |
28 // operation may be important. Implementations of the "BlockOffsetArray" | |
29 // class may be useful in providing such efficient implementations. | |
30 // | |
31 // While generally mirroring the structure of the BOT for GenCollectedHeap, | |
32 // the following types are tailored more towards G1's uses; these should, | |
33 // however, be merged back into a common BOT to avoid code duplication | |
34 // and reduce maintenance overhead. | |
35 // | |
36 // G1BlockOffsetTable (abstract) | |
37 // -- G1BlockOffsetArray (uses G1BlockOffsetSharedArray) | |
38 // -- G1BlockOffsetArrayContigSpace | |
39 // | |
40 // A main impediment to the consolidation of this code might be the | |
41 // effect of making some of the block_start*() calls non-const as | |
42 // below. Whether that might adversely affect performance optimizations | |
43 // that compilers might normally perform in the case of non-G1 | |
44 // collectors needs to be carefully investigated prior to any such | |
45 // consolidation. | |
46 | |
47 // Forward declarations | |
48 class ContiguousSpace; | |
49 class G1BlockOffsetSharedArray; | |
50 | |
51 class G1BlockOffsetTable VALUE_OBJ_CLASS_SPEC { | |
52 friend class VMStructs; | |
53 protected: | |
54 // These members describe the region covered by the table. | |
55 | |
56 // The space this table is covering. | |
57 HeapWord* _bottom; // == reserved.start | |
58 HeapWord* _end; // End of currently allocated region. | |
59 | |
60 public: | |
61 // Initialize the table to cover the given space. | |
62 // The contents of the initial table are undefined. | |
63 G1BlockOffsetTable(HeapWord* bottom, HeapWord* end) : | |
64 _bottom(bottom), _end(end) | |
65 { | |
66 assert(_bottom <= _end, "arguments out of order"); | |
67 } | |
68 | |
69 // Note that the committed size of the covered space may have changed, | |
70 // so the table size might also wish to change. | |
71 virtual void resize(size_t new_word_size) = 0; | |
72 | |
73 virtual void set_bottom(HeapWord* new_bottom) { | |
74 assert(new_bottom <= _end, "new_bottom > _end"); | |
75 _bottom = new_bottom; | |
76 resize(pointer_delta(_end, _bottom)); | |
77 } | |
78 | |
79 // Requires "addr" to be contained by a block, and returns the address of | |
80 // the start of that block. (May have side effects, namely updating of | |
81 // shared array entries that "point" too far backwards. This can occur, | |
82 // for example, when LAB allocation is used in a space covered by the | |
83 // table.) | |
84 virtual HeapWord* block_start_unsafe(const void* addr) = 0; | |
85 // Same as above, but does not have any of the possible side effects | |
86 // discussed above. | |
87 virtual HeapWord* block_start_unsafe_const(const void* addr) const = 0; | |
88 | |
89 // Returns the address of the start of the block containing "addr", or | |
90 // else "null" if it is covered by no block. (May have side effects, | |
91 // namely updating of shared array entries that "point" too far | |
92 // backwards. This can occur, for example, when lab allocation is used | |
93 // in a space covered by the table.) | |
94 inline HeapWord* block_start(const void* addr); | |
95 // Same as above, but does not have any of the possible side effects | |
96 // discussed above. | |
97 inline HeapWord* block_start_const(const void* addr) const; | |
98 }; | |
99 | |
100 // This implementation of "G1BlockOffsetTable" divides the covered region | |
101 // into "N"-word subregions (where "N" = 2^"LogN". An array with an entry | |
102 // for each such subregion indicates how far back one must go to find the | |
103 // start of the chunk that includes the first word of the subregion. | |
104 // | |
105 // Each BlockOffsetArray is owned by a Space. However, the actual array | |
106 // may be shared by several BlockOffsetArrays; this is useful | |
107 // when a single resizable area (such as a generation) is divided up into | |
108 // several spaces in which contiguous allocation takes place, | |
109 // such as, for example, in G1 or in the train generation.) | |
110 | |
111 // Here is the shared array type. | |
112 | |
113 class G1BlockOffsetSharedArray: public CHeapObj { | |
114 friend class G1BlockOffsetArray; | |
115 friend class G1BlockOffsetArrayContigSpace; | |
116 friend class VMStructs; | |
117 | |
118 private: | |
119 // The reserved region covered by the shared array. | |
120 MemRegion _reserved; | |
121 | |
122 // End of the current committed region. | |
123 HeapWord* _end; | |
124 | |
125 // Array for keeping offsets for retrieving object start fast given an | |
126 // address. | |
127 VirtualSpace _vs; | |
128 u_char* _offset_array; // byte array keeping backwards offsets | |
129 | |
130 // Bounds checking accessors: | |
131 // For performance these have to devolve to array accesses in product builds. | |
132 u_char offset_array(size_t index) const { | |
133 assert(index < _vs.committed_size(), "index out of range"); | |
134 return _offset_array[index]; | |
135 } | |
136 | |
137 void set_offset_array(size_t index, u_char offset) { | |
138 assert(index < _vs.committed_size(), "index out of range"); | |
139 assert(offset <= N_words, "offset too large"); | |
140 _offset_array[index] = offset; | |
141 } | |
142 | |
143 void set_offset_array(size_t index, HeapWord* high, HeapWord* low) { | |
144 assert(index < _vs.committed_size(), "index out of range"); | |
145 assert(high >= low, "addresses out of order"); | |
146 assert(pointer_delta(high, low) <= N_words, "offset too large"); | |
147 _offset_array[index] = (u_char) pointer_delta(high, low); | |
148 } | |
149 | |
150 void set_offset_array(HeapWord* left, HeapWord* right, u_char offset) { | |
151 assert(index_for(right - 1) < _vs.committed_size(), | |
152 "right address out of range"); | |
153 assert(left < right, "Heap addresses out of order"); | |
154 size_t num_cards = pointer_delta(right, left) >> LogN_words; | |
155 memset(&_offset_array[index_for(left)], offset, num_cards); | |
156 } | |
157 | |
158 void set_offset_array(size_t left, size_t right, u_char offset) { | |
159 assert(right < _vs.committed_size(), "right address out of range"); | |
160 assert(left <= right, "indexes out of order"); | |
161 size_t num_cards = right - left + 1; | |
162 memset(&_offset_array[left], offset, num_cards); | |
163 } | |
164 | |
165 void check_offset_array(size_t index, HeapWord* high, HeapWord* low) const { | |
166 assert(index < _vs.committed_size(), "index out of range"); | |
167 assert(high >= low, "addresses out of order"); | |
168 assert(pointer_delta(high, low) <= N_words, "offset too large"); | |
169 assert(_offset_array[index] == pointer_delta(high, low), | |
170 "Wrong offset"); | |
171 } | |
172 | |
173 bool is_card_boundary(HeapWord* p) const; | |
174 | |
175 // Return the number of slots needed for an offset array | |
176 // that covers mem_region_words words. | |
177 // We always add an extra slot because if an object | |
178 // ends on a card boundary we put a 0 in the next | |
179 // offset array slot, so we want that slot always | |
180 // to be reserved. | |
181 | |
182 size_t compute_size(size_t mem_region_words) { | |
183 size_t number_of_slots = (mem_region_words / N_words) + 1; | |
184 return ReservedSpace::page_align_size_up(number_of_slots); | |
185 } | |
186 | |
187 public: | |
188 enum SomePublicConstants { | |
189 LogN = 9, | |
190 LogN_words = LogN - LogHeapWordSize, | |
191 N_bytes = 1 << LogN, | |
192 N_words = 1 << LogN_words | |
193 }; | |
194 | |
195 // Initialize the table to cover from "base" to (at least) | |
196 // "base + init_word_size". In the future, the table may be expanded | |
197 // (see "resize" below) up to the size of "_reserved" (which must be at | |
198 // least "init_word_size".) The contents of the initial table are | |
199 // undefined; it is the responsibility of the constituent | |
200 // G1BlockOffsetTable(s) to initialize cards. | |
201 G1BlockOffsetSharedArray(MemRegion reserved, size_t init_word_size); | |
202 | |
203 // Notes a change in the committed size of the region covered by the | |
204 // table. The "new_word_size" may not be larger than the size of the | |
205 // reserved region this table covers. | |
206 void resize(size_t new_word_size); | |
207 | |
208 void set_bottom(HeapWord* new_bottom); | |
209 | |
210 // Updates all the BlockOffsetArray's sharing this shared array to | |
211 // reflect the current "top"'s of their spaces. | |
212 void update_offset_arrays(); | |
213 | |
214 // Return the appropriate index into "_offset_array" for "p". | |
215 inline size_t index_for(const void* p) const; | |
216 | |
217 // Return the address indicating the start of the region corresponding to | |
218 // "index" in "_offset_array". | |
219 inline HeapWord* address_for_index(size_t index) const; | |
220 }; | |
221 | |
222 // And here is the G1BlockOffsetTable subtype that uses the array. | |
223 | |
224 class G1BlockOffsetArray: public G1BlockOffsetTable { | |
225 friend class G1BlockOffsetSharedArray; | |
226 friend class G1BlockOffsetArrayContigSpace; | |
227 friend class VMStructs; | |
228 private: | |
229 enum SomePrivateConstants { | |
230 N_words = G1BlockOffsetSharedArray::N_words, | |
231 LogN = G1BlockOffsetSharedArray::LogN | |
232 }; | |
233 | |
234 // The following enums are used by do_block_helper | |
235 enum Action { | |
236 Action_single, // BOT records a single block (see single_block()) | |
237 Action_mark, // BOT marks the start of a block (see mark_block()) | |
238 Action_check // Check that BOT records block correctly | |
239 // (see verify_single_block()). | |
240 }; | |
241 | |
242 // This is the array, which can be shared by several BlockOffsetArray's | |
243 // servicing different | |
244 G1BlockOffsetSharedArray* _array; | |
245 | |
246 // The space that owns this subregion. | |
247 Space* _sp; | |
248 | |
249 // If "_sp" is a contiguous space, the field below is the view of "_sp" | |
250 // as a contiguous space, else NULL. | |
251 ContiguousSpace* _csp; | |
252 | |
253 // If true, array entries are initialized to 0; otherwise, they are | |
254 // initialized to point backwards to the beginning of the covered region. | |
255 bool _init_to_zero; | |
256 | |
257 // The portion [_unallocated_block, _sp.end()) of the space that | |
258 // is a single block known not to contain any objects. | |
259 // NOTE: See BlockOffsetArrayUseUnallocatedBlock flag. | |
260 HeapWord* _unallocated_block; | |
261 | |
262 // Sets the entries | |
263 // corresponding to the cards starting at "start" and ending at "end" | |
264 // to point back to the card before "start": the interval [start, end) | |
265 // is right-open. | |
266 void set_remainder_to_point_to_start(HeapWord* start, HeapWord* end); | |
267 // Same as above, except that the args here are a card _index_ interval | |
268 // that is closed: [start_index, end_index] | |
269 void set_remainder_to_point_to_start_incl(size_t start, size_t end); | |
270 | |
271 // A helper function for BOT adjustment/verification work | |
272 void do_block_internal(HeapWord* blk_start, HeapWord* blk_end, Action action); | |
273 | |
274 protected: | |
275 | |
276 ContiguousSpace* csp() const { return _csp; } | |
277 | |
278 // Returns the address of a block whose start is at most "addr". | |
279 // If "has_max_index" is true, "assumes "max_index" is the last valid one | |
280 // in the array. | |
281 inline HeapWord* block_at_or_preceding(const void* addr, | |
282 bool has_max_index, | |
283 size_t max_index) const; | |
284 | |
285 // "q" is a block boundary that is <= "addr"; "n" is the address of the | |
286 // next block (or the end of the space.) Return the address of the | |
287 // beginning of the block that contains "addr". Does so without side | |
288 // effects (see, e.g., spec of block_start.) | |
289 inline HeapWord* | |
290 forward_to_block_containing_addr_const(HeapWord* q, HeapWord* n, | |
291 const void* addr) const; | |
292 | |
293 // "q" is a block boundary that is <= "addr"; return the address of the | |
294 // beginning of the block that contains "addr". May have side effects | |
295 // on "this", by updating imprecise entries. | |
296 inline HeapWord* forward_to_block_containing_addr(HeapWord* q, | |
297 const void* addr); | |
298 | |
299 // "q" is a block boundary that is <= "addr"; "n" is the address of the | |
300 // next block (or the end of the space.) Return the address of the | |
301 // beginning of the block that contains "addr". May have side effects | |
302 // on "this", by updating imprecise entries. | |
303 HeapWord* forward_to_block_containing_addr_slow(HeapWord* q, | |
304 HeapWord* n, | |
305 const void* addr); | |
306 | |
307 // Requires that "*threshold_" be the first array entry boundary at or | |
308 // above "blk_start", and that "*index_" be the corresponding array | |
309 // index. If the block starts at or crosses "*threshold_", records | |
310 // "blk_start" as the appropriate block start for the array index | |
311 // starting at "*threshold_", and for any other indices crossed by the | |
312 // block. Updates "*threshold_" and "*index_" to correspond to the first | |
313 // index after the block end. | |
314 void alloc_block_work2(HeapWord** threshold_, size_t* index_, | |
315 HeapWord* blk_start, HeapWord* blk_end); | |
316 | |
317 public: | |
318 // The space may not have it's bottom and top set yet, which is why the | |
319 // region is passed as a parameter. If "init_to_zero" is true, the | |
320 // elements of the array are initialized to zero. Otherwise, they are | |
321 // initialized to point backwards to the beginning. | |
322 G1BlockOffsetArray(G1BlockOffsetSharedArray* array, MemRegion mr, | |
323 bool init_to_zero); | |
324 | |
325 // Note: this ought to be part of the constructor, but that would require | |
326 // "this" to be passed as a parameter to a member constructor for | |
327 // the containing concrete subtype of Space. | |
328 // This would be legal C++, but MS VC++ doesn't allow it. | |
329 void set_space(Space* sp); | |
330 | |
331 // Resets the covered region to the given "mr". | |
332 void set_region(MemRegion mr); | |
333 | |
334 // Resets the covered region to one with the same _bottom as before but | |
335 // the "new_word_size". | |
336 void resize(size_t new_word_size); | |
337 | |
338 // These must be guaranteed to work properly (i.e., do nothing) | |
339 // when "blk_start" ("blk" for second version) is "NULL". | |
340 virtual void alloc_block(HeapWord* blk_start, HeapWord* blk_end); | |
341 virtual void alloc_block(HeapWord* blk, size_t size) { | |
342 alloc_block(blk, blk + size); | |
343 } | |
344 | |
345 // The following methods are useful and optimized for a | |
346 // general, non-contiguous space. | |
347 | |
348 // The given arguments are required to be the starts of adjacent ("blk1" | |
349 // before "blk2") well-formed blocks covered by "this". After this call, | |
350 // they should be considered to form one block. | |
351 virtual void join_blocks(HeapWord* blk1, HeapWord* blk2); | |
352 | |
353 // Given a block [blk_start, blk_start + full_blk_size), and | |
354 // a left_blk_size < full_blk_size, adjust the BOT to show two | |
355 // blocks [blk_start, blk_start + left_blk_size) and | |
356 // [blk_start + left_blk_size, blk_start + full_blk_size). | |
357 // It is assumed (and verified in the non-product VM) that the | |
358 // BOT was correct for the original block. | |
359 void split_block(HeapWord* blk_start, size_t full_blk_size, | |
360 size_t left_blk_size); | |
361 | |
362 // Adjust the BOT to show that it has a single block in the | |
363 // range [blk_start, blk_start + size). All necessary BOT | |
364 // cards are adjusted, but _unallocated_block isn't. | |
365 void single_block(HeapWord* blk_start, HeapWord* blk_end); | |
366 void single_block(HeapWord* blk, size_t size) { | |
367 single_block(blk, blk + size); | |
368 } | |
369 | |
370 // Adjust BOT to show that it has a block in the range | |
371 // [blk_start, blk_start + size). Only the first card | |
372 // of BOT is touched. It is assumed (and verified in the | |
373 // non-product VM) that the remaining cards of the block | |
374 // are correct. | |
375 void mark_block(HeapWord* blk_start, HeapWord* blk_end); | |
376 void mark_block(HeapWord* blk, size_t size) { | |
377 mark_block(blk, blk + size); | |
378 } | |
379 | |
380 // Adjust _unallocated_block to indicate that a particular | |
381 // block has been newly allocated or freed. It is assumed (and | |
382 // verified in the non-product VM) that the BOT is correct for | |
383 // the given block. | |
384 inline void allocated(HeapWord* blk_start, HeapWord* blk_end) { | |
385 // Verify that the BOT shows [blk, blk + blk_size) to be one block. | |
386 verify_single_block(blk_start, blk_end); | |
387 if (BlockOffsetArrayUseUnallocatedBlock) { | |
388 _unallocated_block = MAX2(_unallocated_block, blk_end); | |
389 } | |
390 } | |
391 | |
392 inline void allocated(HeapWord* blk, size_t size) { | |
393 allocated(blk, blk + size); | |
394 } | |
395 | |
396 inline void freed(HeapWord* blk_start, HeapWord* blk_end); | |
397 | |
398 inline void freed(HeapWord* blk, size_t size); | |
399 | |
400 virtual HeapWord* block_start_unsafe(const void* addr); | |
401 virtual HeapWord* block_start_unsafe_const(const void* addr) const; | |
402 | |
403 // Requires "addr" to be the start of a card and returns the | |
404 // start of the block that contains the given address. | |
405 HeapWord* block_start_careful(const void* addr) const; | |
406 | |
407 // If true, initialize array slots with no allocated blocks to zero. | |
408 // Otherwise, make them point back to the front. | |
409 bool init_to_zero() { return _init_to_zero; } | |
410 | |
411 // Verification & debugging - ensure that the offset table reflects the fact | |
412 // that the block [blk_start, blk_end) or [blk, blk + size) is a | |
413 // single block of storage. NOTE: can;t const this because of | |
414 // call to non-const do_block_internal() below. | |
415 inline void verify_single_block(HeapWord* blk_start, HeapWord* blk_end) { | |
416 if (VerifyBlockOffsetArray) { | |
417 do_block_internal(blk_start, blk_end, Action_check); | |
418 } | |
419 } | |
420 | |
421 inline void verify_single_block(HeapWord* blk, size_t size) { | |
422 verify_single_block(blk, blk + size); | |
423 } | |
424 | |
425 // Verify that the given block is before _unallocated_block | |
426 inline void verify_not_unallocated(HeapWord* blk_start, | |
427 HeapWord* blk_end) const { | |
428 if (BlockOffsetArrayUseUnallocatedBlock) { | |
429 assert(blk_start < blk_end, "Block inconsistency?"); | |
430 assert(blk_end <= _unallocated_block, "_unallocated_block problem"); | |
431 } | |
432 } | |
433 | |
434 inline void verify_not_unallocated(HeapWord* blk, size_t size) const { | |
435 verify_not_unallocated(blk, blk + size); | |
436 } | |
437 | |
438 void check_all_cards(size_t left_card, size_t right_card) const; | |
439 }; | |
440 | |
441 // A subtype of BlockOffsetArray that takes advantage of the fact | |
442 // that its underlying space is a ContiguousSpace, so that its "active" | |
443 // region can be more efficiently tracked (than for a non-contiguous space). | |
444 class G1BlockOffsetArrayContigSpace: public G1BlockOffsetArray { | |
445 friend class VMStructs; | |
446 | |
447 // allocation boundary at which offset array must be updated | |
448 HeapWord* _next_offset_threshold; | |
449 size_t _next_offset_index; // index corresponding to that boundary | |
450 | |
451 // Work function to be called when allocation start crosses the next | |
452 // threshold in the contig space. | |
453 void alloc_block_work1(HeapWord* blk_start, HeapWord* blk_end) { | |
454 alloc_block_work2(&_next_offset_threshold, &_next_offset_index, | |
455 blk_start, blk_end); | |
456 } | |
457 | |
458 | |
459 public: | |
460 G1BlockOffsetArrayContigSpace(G1BlockOffsetSharedArray* array, MemRegion mr); | |
461 | |
462 // Initialize the threshold to reflect the first boundary after the | |
463 // bottom of the covered region. | |
464 HeapWord* initialize_threshold(); | |
465 | |
466 // Zero out the entry for _bottom (offset will be zero). | |
467 void zero_bottom_entry(); | |
468 | |
469 // Return the next threshold, the point at which the table should be | |
470 // updated. | |
471 HeapWord* threshold() const { return _next_offset_threshold; } | |
472 | |
473 // These must be guaranteed to work properly (i.e., do nothing) | |
474 // when "blk_start" ("blk" for second version) is "NULL". In this | |
475 // implementation, that's true because NULL is represented as 0, and thus | |
476 // never exceeds the "_next_offset_threshold". | |
477 void alloc_block(HeapWord* blk_start, HeapWord* blk_end) { | |
478 if (blk_end > _next_offset_threshold) | |
479 alloc_block_work1(blk_start, blk_end); | |
480 } | |
481 void alloc_block(HeapWord* blk, size_t size) { | |
482 alloc_block(blk, blk+size); | |
483 } | |
484 | |
485 HeapWord* block_start_unsafe(const void* addr); | |
486 HeapWord* block_start_unsafe_const(const void* addr) const; | |
487 }; |