1 /*
2 * Copyright (c) 2005, 2017, Oracle and/or its affiliates. All rights reserved.
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 *
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_PARALLEL_PARMARKBITMAP_HPP
26 #define SHARE_VM_GC_PARALLEL_PARMARKBITMAP_HPP
27
28 #include "memory/memRegion.hpp"
29 #include "oops/oop.hpp"
30 #include "utilities/bitMap.hpp"
31
32 class ParMarkBitMapClosure;
33 class PSVirtualSpace;
34 class ParCompactionManager;
35
36 class ParMarkBitMap: public CHeapObj<mtGC>
37 {
38 public:
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
170 private:
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 inline ParMarkBitMap::ParMarkBitMap():
192 _beg_bits(), _end_bits(), _region_start(NULL), _region_size(0), _virtual_space(NULL), _reserved_byte_size(0)
193 { }
194
195 inline void ParMarkBitMap::clear_range(idx_t beg, idx_t end)
196 {
197 _beg_bits.clear_range(beg, end);
198 _end_bits.clear_range(beg, end);
199 }
200
201 inline ParMarkBitMap::idx_t
202 ParMarkBitMap::bits_required(size_t words)
203 {
204 // Need two bits (one begin bit, one end bit) for each unit of 'object
205 // granularity' in the heap.
206 return words_to_bits(words * 2);
207 }
208
209 inline ParMarkBitMap::idx_t
210 ParMarkBitMap::bits_required(MemRegion covered_region)
211 {
212 return bits_required(covered_region.word_size());
213 }
214
215 inline HeapWord*
216 ParMarkBitMap::region_start() const
217 {
218 return _region_start;
219 }
220
221 inline HeapWord*
222 ParMarkBitMap::region_end() const
223 {
224 return region_start() + region_size();
225 }
226
227 inline size_t
228 ParMarkBitMap::region_size() const
229 {
230 return _region_size;
231 }
232
233 inline size_t
234 ParMarkBitMap::size() const
235 {
236 return _beg_bits.size();
237 }
238
239 inline bool ParMarkBitMap::is_obj_beg(idx_t bit) const
240 {
241 return _beg_bits.at(bit);
242 }
243
244 inline bool ParMarkBitMap::is_obj_end(idx_t bit) const
245 {
246 return _end_bits.at(bit);
247 }
248
249 inline bool ParMarkBitMap::is_marked(idx_t bit) const
250 {
251 return is_obj_beg(bit);
252 }
253
254 inline bool ParMarkBitMap::is_marked(HeapWord* addr) const
255 {
256 return is_marked(addr_to_bit(addr));
257 }
258
259 inline bool ParMarkBitMap::is_marked(oop obj) const
260 {
261 return is_marked((HeapWord*)obj);
262 }
263
264 inline bool ParMarkBitMap::is_unmarked(idx_t bit) const
265 {
266 return !is_marked(bit);
267 }
268
269 inline bool ParMarkBitMap::is_unmarked(HeapWord* addr) const
270 {
271 return !is_marked(addr);
272 }
273
274 inline bool ParMarkBitMap::is_unmarked(oop obj) const
275 {
276 return !is_marked(obj);
277 }
278
279 inline size_t
280 ParMarkBitMap::bits_to_words(idx_t bits)
281 {
282 return bits << obj_granularity_shift();
283 }
284
285 inline ParMarkBitMap::idx_t
286 ParMarkBitMap::words_to_bits(size_t words)
287 {
288 return words >> obj_granularity_shift();
289 }
290
291 inline size_t ParMarkBitMap::obj_size(idx_t beg_bit, idx_t end_bit) const
292 {
293 DEBUG_ONLY(verify_bit(beg_bit);)
294 DEBUG_ONLY(verify_bit(end_bit);)
295 return bits_to_words(end_bit - beg_bit + 1);
296 }
297
298 inline size_t
299 ParMarkBitMap::obj_size(HeapWord* beg_addr, HeapWord* end_addr) const
300 {
301 DEBUG_ONLY(verify_addr(beg_addr);)
302 DEBUG_ONLY(verify_addr(end_addr);)
303 return pointer_delta(end_addr, beg_addr) + obj_granularity();
304 }
305
306 inline size_t ParMarkBitMap::obj_size(idx_t beg_bit) const
307 {
308 const idx_t end_bit = _end_bits.get_next_one_offset(beg_bit, size());
309 assert(is_marked(beg_bit), "obj not marked");
310 assert(end_bit < size(), "end bit missing");
311 return obj_size(beg_bit, end_bit);
312 }
313
314 inline size_t ParMarkBitMap::obj_size(HeapWord* addr) const
315 {
316 return obj_size(addr_to_bit(addr));
317 }
318
319 inline ParMarkBitMap::IterationStatus
320 ParMarkBitMap::iterate(ParMarkBitMapClosure* live_closure,
321 HeapWord* range_beg,
322 HeapWord* range_end) const
323 {
324 return iterate(live_closure, addr_to_bit(range_beg), addr_to_bit(range_end));
325 }
326
327 inline ParMarkBitMap::IterationStatus
328 ParMarkBitMap::iterate(ParMarkBitMapClosure* live_closure,
329 ParMarkBitMapClosure* dead_closure,
330 HeapWord* range_beg,
331 HeapWord* range_end,
332 HeapWord* dead_range_end) const
333 {
334 return iterate(live_closure, dead_closure,
335 addr_to_bit(range_beg), addr_to_bit(range_end),
336 addr_to_bit(dead_range_end));
337 }
338
339 inline bool
340 ParMarkBitMap::mark_obj(oop obj, int size)
341 {
342 return mark_obj((HeapWord*)obj, (size_t)size);
343 }
344
345 inline BitMap::idx_t
346 ParMarkBitMap::addr_to_bit(HeapWord* addr) const
347 {
348 DEBUG_ONLY(verify_addr(addr);)
349 return words_to_bits(pointer_delta(addr, region_start()));
350 }
351
352 inline HeapWord*
353 ParMarkBitMap::bit_to_addr(idx_t bit) const
354 {
355 DEBUG_ONLY(verify_bit(bit);)
356 return region_start() + bits_to_words(bit);
357 }
358
359 inline ParMarkBitMap::idx_t
360 ParMarkBitMap::find_obj_beg(idx_t beg, idx_t end) const
361 {
362 return _beg_bits.get_next_one_offset_aligned_right(beg, end);
363 }
364
365 inline ParMarkBitMap::idx_t
366 ParMarkBitMap::find_obj_end(idx_t beg, idx_t end) const
367 {
368 return _end_bits.get_next_one_offset_aligned_right(beg, end);
369 }
370
371 inline HeapWord*
372 ParMarkBitMap::find_obj_beg(HeapWord* beg, HeapWord* end) const
373 {
374 const idx_t beg_bit = addr_to_bit(beg);
375 const idx_t end_bit = addr_to_bit(end);
376 const idx_t search_end = BitMap::word_align_up(end_bit);
377 const idx_t res_bit = MIN2(find_obj_beg(beg_bit, search_end), end_bit);
378 return bit_to_addr(res_bit);
379 }
380
381 inline HeapWord*
382 ParMarkBitMap::find_obj_end(HeapWord* beg, HeapWord* end) const
383 {
384 const idx_t beg_bit = addr_to_bit(beg);
385 const idx_t end_bit = addr_to_bit(end);
386 const idx_t search_end = BitMap::word_align_up(end_bit);
387 const idx_t res_bit = MIN2(find_obj_end(beg_bit, search_end), end_bit);
388 return bit_to_addr(res_bit);
389 }
390
391 #ifdef ASSERT
392 inline void ParMarkBitMap::verify_bit(idx_t bit) const {
393 // Allow one past the last valid bit; useful for loop bounds.
394 assert(bit <= _beg_bits.size(), "bit out of range");
395 }
396
397 inline void ParMarkBitMap::verify_addr(HeapWord* addr) const {
398 // Allow one past the last valid address; useful for loop bounds.
399 assert(addr >= region_start(),
400 "addr too small, addr: " PTR_FORMAT " region start: " PTR_FORMAT, p2i(addr), p2i(region_start()));
401 assert(addr <= region_end(),
402 "addr too big, addr: " PTR_FORMAT " region end: " PTR_FORMAT, p2i(addr), p2i(region_end()));
403 }
404 #endif // #ifdef ASSERT
405
406 #endif // SHARE_VM_GC_PARALLEL_PARMARKBITMAP_HPP