Mercurial > hg > truffle
annotate src/share/vm/oops/markOop.hpp @ 19177:1a7b33c96c0d
Fixes for TruffleGraphBuilderPluginsProvider.
author | Thomas Wuerthinger <thomas.wuerthinger@oracle.com> |
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date | Fri, 06 Feb 2015 16:49:34 +0100 |
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0 | 1 /* |
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2 * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved. |
0 | 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. |
0 | 22 * |
23 */ | |
24 | |
1972 | 25 #ifndef SHARE_VM_OOPS_MARKOOP_HPP |
26 #define SHARE_VM_OOPS_MARKOOP_HPP | |
27 | |
28 #include "oops/oop.hpp" | |
29 | |
0 | 30 // The markOop describes the header of an object. |
31 // | |
32 // Note that the mark is not a real oop but just a word. | |
33 // It is placed in the oop hierarchy for historical reasons. | |
34 // | |
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35 // Bit-format of an object header (most significant first, big endian layout below): |
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36 // |
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37 // 32 bits: |
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38 // -------- |
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39 // hash:25 ------------>| age:4 biased_lock:1 lock:2 (normal object) |
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40 // JavaThread*:23 epoch:2 age:4 biased_lock:1 lock:2 (biased object) |
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41 // size:32 ------------------------------------------>| (CMS free block) |
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42 // PromotedObject*:29 ---------->| promo_bits:3 ----->| (CMS promoted object) |
0 | 43 // |
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44 // 64 bits: |
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45 // -------- |
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46 // unused:25 hash:31 -->| unused:1 age:4 biased_lock:1 lock:2 (normal object) |
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47 // JavaThread*:54 epoch:2 unused:1 age:4 biased_lock:1 lock:2 (biased object) |
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48 // PromotedObject*:61 --------------------->| promo_bits:3 ----->| (CMS promoted object) |
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49 // size:64 ----------------------------------------------------->| (CMS free block) |
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50 // |
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51 // unused:25 hash:31 -->| cms_free:1 age:4 biased_lock:1 lock:2 (COOPs && normal object) |
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52 // JavaThread*:54 epoch:2 cms_free:1 age:4 biased_lock:1 lock:2 (COOPs && biased object) |
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53 // narrowOop:32 unused:24 cms_free:1 unused:4 promo_bits:3 ----->| (COOPs && CMS promoted object) |
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54 // unused:21 size:35 -->| cms_free:1 unused:7 ------------------>| (COOPs && CMS free block) |
0 | 55 // |
56 // - hash contains the identity hash value: largest value is | |
57 // 31 bits, see os::random(). Also, 64-bit vm's require | |
58 // a hash value no bigger than 32 bits because they will not | |
59 // properly generate a mask larger than that: see library_call.cpp | |
60 // and c1_CodePatterns_sparc.cpp. | |
61 // | |
62 // - the biased lock pattern is used to bias a lock toward a given | |
63 // thread. When this pattern is set in the low three bits, the lock | |
64 // is either biased toward a given thread or "anonymously" biased, | |
65 // indicating that it is possible for it to be biased. When the | |
66 // lock is biased toward a given thread, locking and unlocking can | |
67 // be performed by that thread without using atomic operations. | |
68 // When a lock's bias is revoked, it reverts back to the normal | |
69 // locking scheme described below. | |
70 // | |
71 // Note that we are overloading the meaning of the "unlocked" state | |
72 // of the header. Because we steal a bit from the age we can | |
73 // guarantee that the bias pattern will never be seen for a truly | |
74 // unlocked object. | |
75 // | |
76 // Note also that the biased state contains the age bits normally | |
77 // contained in the object header. Large increases in scavenge | |
78 // times were seen when these bits were absent and an arbitrary age | |
79 // assigned to all biased objects, because they tended to consume a | |
80 // significant fraction of the eden semispaces and were not | |
81 // promoted promptly, causing an increase in the amount of copying | |
82 // performed. The runtime system aligns all JavaThread* pointers to | |
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83 // a very large value (currently 128 bytes (32bVM) or 256 bytes (64bVM)) |
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84 // to make room for the age bits & the epoch bits (used in support of |
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85 // biased locking), and for the CMS "freeness" bit in the 64bVM (+COOPs). |
0 | 86 // |
87 // [JavaThread* | epoch | age | 1 | 01] lock is biased toward given thread | |
88 // [0 | epoch | age | 1 | 01] lock is anonymously biased | |
89 // | |
90 // - the two lock bits are used to describe three states: locked/unlocked and monitor. | |
91 // | |
92 // [ptr | 00] locked ptr points to real header on stack | |
93 // [header | 0 | 01] unlocked regular object header | |
94 // [ptr | 10] monitor inflated lock (header is wapped out) | |
95 // [ptr | 11] marked used by markSweep to mark an object | |
96 // not valid at any other time | |
97 // | |
98 // We assume that stack/thread pointers have the lowest two bits cleared. | |
99 | |
100 class BasicLock; | |
101 class ObjectMonitor; | |
102 class JavaThread; | |
103 | |
104 class markOopDesc: public oopDesc { | |
105 private: | |
106 // Conversion | |
107 uintptr_t value() const { return (uintptr_t) this; } | |
108 | |
109 public: | |
110 // Constants | |
111 enum { age_bits = 4, | |
112 lock_bits = 2, | |
113 biased_lock_bits = 1, | |
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114 max_hash_bits = BitsPerWord - age_bits - lock_bits - biased_lock_bits, |
0 | 115 hash_bits = max_hash_bits > 31 ? 31 : max_hash_bits, |
187 | 116 cms_bits = LP64_ONLY(1) NOT_LP64(0), |
0 | 117 epoch_bits = 2 |
118 }; | |
119 | |
120 // The biased locking code currently requires that the age bits be | |
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121 // contiguous to the lock bits. |
0 | 122 enum { lock_shift = 0, |
123 biased_lock_shift = lock_bits, | |
124 age_shift = lock_bits + biased_lock_bits, | |
187 | 125 cms_shift = age_shift + age_bits, |
126 hash_shift = cms_shift + cms_bits, | |
0 | 127 epoch_shift = hash_shift |
128 }; | |
129 | |
130 enum { lock_mask = right_n_bits(lock_bits), | |
131 lock_mask_in_place = lock_mask << lock_shift, | |
132 biased_lock_mask = right_n_bits(lock_bits + biased_lock_bits), | |
133 biased_lock_mask_in_place= biased_lock_mask << lock_shift, | |
134 biased_lock_bit_in_place = 1 << biased_lock_shift, | |
135 age_mask = right_n_bits(age_bits), | |
136 age_mask_in_place = age_mask << age_shift, | |
137 epoch_mask = right_n_bits(epoch_bits), | |
187 | 138 epoch_mask_in_place = epoch_mask << epoch_shift, |
139 cms_mask = right_n_bits(cms_bits), | |
140 cms_mask_in_place = cms_mask << cms_shift | |
0 | 141 #ifndef _WIN64 |
142 ,hash_mask = right_n_bits(hash_bits), | |
143 hash_mask_in_place = (address_word)hash_mask << hash_shift | |
144 #endif | |
145 }; | |
146 | |
147 // Alignment of JavaThread pointers encoded in object header required by biased locking | |
148 enum { biased_lock_alignment = 2 << (epoch_shift + epoch_bits) | |
149 }; | |
150 | |
151 #ifdef _WIN64 | |
152 // These values are too big for Win64 | |
153 const static uintptr_t hash_mask = right_n_bits(hash_bits); | |
154 const static uintptr_t hash_mask_in_place = | |
155 (address_word)hash_mask << hash_shift; | |
156 #endif | |
157 | |
158 enum { locked_value = 0, | |
159 unlocked_value = 1, | |
160 monitor_value = 2, | |
161 marked_value = 3, | |
162 biased_lock_pattern = 5 | |
163 }; | |
164 | |
165 enum { no_hash = 0 }; // no hash value assigned | |
166 | |
167 enum { no_hash_in_place = (address_word)no_hash << hash_shift, | |
168 no_lock_in_place = unlocked_value | |
169 }; | |
170 | |
171 enum { max_age = age_mask }; | |
172 | |
173 enum { max_bias_epoch = epoch_mask }; | |
174 | |
175 // Biased Locking accessors. | |
176 // These must be checked by all code which calls into the | |
177 // ObjectSynchronizer and other code. The biasing is not understood | |
178 // by the lower-level CAS-based locking code, although the runtime | |
179 // fixes up biased locks to be compatible with it when a bias is | |
180 // revoked. | |
181 bool has_bias_pattern() const { | |
182 return (mask_bits(value(), biased_lock_mask_in_place) == biased_lock_pattern); | |
183 } | |
184 JavaThread* biased_locker() const { | |
185 assert(has_bias_pattern(), "should not call this otherwise"); | |
186 return (JavaThread*) ((intptr_t) (mask_bits(value(), ~(biased_lock_mask_in_place | age_mask_in_place | epoch_mask_in_place)))); | |
187 } | |
188 // Indicates that the mark has the bias bit set but that it has not | |
189 // yet been biased toward a particular thread | |
190 bool is_biased_anonymously() const { | |
191 return (has_bias_pattern() && (biased_locker() == NULL)); | |
192 } | |
193 // Indicates epoch in which this bias was acquired. If the epoch | |
194 // changes due to too many bias revocations occurring, the biases | |
195 // from the previous epochs are all considered invalid. | |
196 int bias_epoch() const { | |
197 assert(has_bias_pattern(), "should not call this otherwise"); | |
198 return (mask_bits(value(), epoch_mask_in_place) >> epoch_shift); | |
199 } | |
200 markOop set_bias_epoch(int epoch) { | |
201 assert(has_bias_pattern(), "should not call this otherwise"); | |
202 assert((epoch & (~epoch_mask)) == 0, "epoch overflow"); | |
203 return markOop(mask_bits(value(), ~epoch_mask_in_place) | (epoch << epoch_shift)); | |
204 } | |
205 markOop incr_bias_epoch() { | |
206 return set_bias_epoch((1 + bias_epoch()) & epoch_mask); | |
207 } | |
208 // Prototype mark for initialization | |
209 static markOop biased_locking_prototype() { | |
210 return markOop( biased_lock_pattern ); | |
211 } | |
212 | |
213 // lock accessors (note that these assume lock_shift == 0) | |
214 bool is_locked() const { | |
215 return (mask_bits(value(), lock_mask_in_place) != unlocked_value); | |
216 } | |
217 bool is_unlocked() const { | |
218 return (mask_bits(value(), biased_lock_mask_in_place) == unlocked_value); | |
219 } | |
220 bool is_marked() const { | |
221 return (mask_bits(value(), lock_mask_in_place) == marked_value); | |
222 } | |
223 bool is_neutral() const { return (mask_bits(value(), biased_lock_mask_in_place) == unlocked_value); } | |
224 | |
225 // Special temporary state of the markOop while being inflated. | |
226 // Code that looks at mark outside a lock need to take this into account. | |
227 bool is_being_inflated() const { return (value() == 0); } | |
228 | |
229 // Distinguished markword value - used when inflating over | |
230 // an existing stacklock. 0 indicates the markword is "BUSY". | |
231 // Lockword mutators that use a LD...CAS idiom should always | |
232 // check for and avoid overwriting a 0 value installed by some | |
233 // other thread. (They should spin or block instead. The 0 value | |
234 // is transient and *should* be short-lived). | |
235 static markOop INFLATING() { return (markOop) 0; } // inflate-in-progress | |
236 | |
237 // Should this header be preserved during GC? | |
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238 inline bool must_be_preserved(oop obj_containing_mark) const; |
0 | 239 inline bool must_be_preserved_with_bias(oop obj_containing_mark) const; |
240 | |
241 // Should this header (including its age bits) be preserved in the | |
242 // case of a promotion failure during scavenge? | |
243 // Note that we special case this situation. We want to avoid | |
244 // calling BiasedLocking::preserve_marks()/restore_marks() (which | |
245 // decrease the number of mark words that need to be preserved | |
246 // during GC) during each scavenge. During scavenges in which there | |
247 // is no promotion failure, we actually don't need to call the above | |
248 // routines at all, since we don't mutate and re-initialize the | |
249 // marks of promoted objects using init_mark(). However, during | |
250 // scavenges which result in promotion failure, we do re-initialize | |
251 // the mark words of objects, meaning that we should have called | |
252 // these mark word preservation routines. Currently there's no good | |
253 // place in which to call them in any of the scavengers (although | |
254 // guarded by appropriate locks we could make one), but the | |
255 // observation is that promotion failures are quite rare and | |
256 // reducing the number of mark words preserved during them isn't a | |
257 // high priority. | |
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258 inline bool must_be_preserved_for_promotion_failure(oop obj_containing_mark) const; |
0 | 259 inline bool must_be_preserved_with_bias_for_promotion_failure(oop obj_containing_mark) const; |
260 | |
261 // Should this header be preserved during a scavenge where CMS is | |
262 // the old generation? | |
263 // (This is basically the same body as must_be_preserved_for_promotion_failure(), | |
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264 // but takes the Klass* as argument instead) |
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265 inline bool must_be_preserved_for_cms_scavenge(Klass* klass_of_obj_containing_mark) const; |
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266 inline bool must_be_preserved_with_bias_for_cms_scavenge(Klass* klass_of_obj_containing_mark) const; |
0 | 267 |
268 // WARNING: The following routines are used EXCLUSIVELY by | |
269 // synchronization functions. They are not really gc safe. | |
270 // They must get updated if markOop layout get changed. | |
271 markOop set_unlocked() const { | |
272 return markOop(value() | unlocked_value); | |
273 } | |
274 bool has_locker() const { | |
275 return ((value() & lock_mask_in_place) == locked_value); | |
276 } | |
277 BasicLock* locker() const { | |
278 assert(has_locker(), "check"); | |
279 return (BasicLock*) value(); | |
280 } | |
281 bool has_monitor() const { | |
282 return ((value() & monitor_value) != 0); | |
283 } | |
284 ObjectMonitor* monitor() const { | |
285 assert(has_monitor(), "check"); | |
286 // Use xor instead of &~ to provide one extra tag-bit check. | |
287 return (ObjectMonitor*) (value() ^ monitor_value); | |
288 } | |
289 bool has_displaced_mark_helper() const { | |
290 return ((value() & unlocked_value) == 0); | |
291 } | |
292 markOop displaced_mark_helper() const { | |
293 assert(has_displaced_mark_helper(), "check"); | |
294 intptr_t ptr = (value() & ~monitor_value); | |
295 return *(markOop*)ptr; | |
296 } | |
297 void set_displaced_mark_helper(markOop m) const { | |
298 assert(has_displaced_mark_helper(), "check"); | |
299 intptr_t ptr = (value() & ~monitor_value); | |
300 *(markOop*)ptr = m; | |
301 } | |
302 markOop copy_set_hash(intptr_t hash) const { | |
303 intptr_t tmp = value() & (~hash_mask_in_place); | |
304 tmp |= ((hash & hash_mask) << hash_shift); | |
305 return (markOop)tmp; | |
306 } | |
307 // it is only used to be stored into BasicLock as the | |
308 // indicator that the lock is using heavyweight monitor | |
309 static markOop unused_mark() { | |
310 return (markOop) marked_value; | |
311 } | |
312 // the following two functions create the markOop to be | |
313 // stored into object header, it encodes monitor info | |
314 static markOop encode(BasicLock* lock) { | |
315 return (markOop) lock; | |
316 } | |
317 static markOop encode(ObjectMonitor* monitor) { | |
318 intptr_t tmp = (intptr_t) monitor; | |
319 return (markOop) (tmp | monitor_value); | |
320 } | |
6818 | 321 static markOop encode(JavaThread* thread, uint age, int bias_epoch) { |
0 | 322 intptr_t tmp = (intptr_t) thread; |
323 assert(UseBiasedLocking && ((tmp & (epoch_mask_in_place | age_mask_in_place | biased_lock_mask_in_place)) == 0), "misaligned JavaThread pointer"); | |
324 assert(age <= max_age, "age too large"); | |
325 assert(bias_epoch <= max_bias_epoch, "bias epoch too large"); | |
326 return (markOop) (tmp | (bias_epoch << epoch_shift) | (age << age_shift) | biased_lock_pattern); | |
327 } | |
328 | |
329 // used to encode pointers during GC | |
330 markOop clear_lock_bits() { return markOop(value() & ~lock_mask_in_place); } | |
331 | |
332 // age operations | |
333 markOop set_marked() { return markOop((value() & ~lock_mask_in_place) | marked_value); } | |
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334 markOop set_unmarked() { return markOop((value() & ~lock_mask_in_place) | unlocked_value); } |
0 | 335 |
6818 | 336 uint age() const { return mask_bits(value() >> age_shift, age_mask); } |
337 markOop set_age(uint v) const { | |
0 | 338 assert((v & ~age_mask) == 0, "shouldn't overflow age field"); |
6818 | 339 return markOop((value() & ~age_mask_in_place) | (((uintptr_t)v & age_mask) << age_shift)); |
0 | 340 } |
341 markOop incr_age() const { return age() == max_age ? markOop(this) : set_age(age() + 1); } | |
342 | |
343 // hash operations | |
344 intptr_t hash() const { | |
345 return mask_bits(value() >> hash_shift, hash_mask); | |
346 } | |
347 | |
348 bool has_no_hash() const { | |
349 return hash() == no_hash; | |
350 } | |
351 | |
352 // Prototype mark for initialization | |
353 static markOop prototype() { | |
354 return markOop( no_hash_in_place | no_lock_in_place ); | |
355 } | |
356 | |
357 // Helper function for restoration of unmarked mark oops during GC | |
358 static inline markOop prototype_for_object(oop obj); | |
359 | |
360 // Debugging | |
361 void print_on(outputStream* st) const; | |
362 | |
363 // Prepare address of oop for placement into mark | |
364 inline static markOop encode_pointer_as_mark(void* p) { return markOop(p)->set_marked(); } | |
365 | |
366 // Recover address of oop from encoded form used in mark | |
367 inline void* decode_pointer() { if (UseBiasedLocking && has_bias_pattern()) return NULL; return clear_lock_bits(); } | |
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368 |
187 | 369 // These markOops indicate cms free chunk blocks and not objects. |
370 // In 64 bit, the markOop is set to distinguish them from oops. | |
371 // These are defined in 32 bit mode for vmStructs. | |
372 const static uintptr_t cms_free_chunk_pattern = 0x1; | |
373 | |
374 // Constants for the size field. | |
375 enum { size_shift = cms_shift + cms_bits, | |
376 size_bits = 35 // need for compressed oops 32G | |
377 }; | |
378 // These values are too big for Win64 | |
379 const static uintptr_t size_mask = LP64_ONLY(right_n_bits(size_bits)) | |
380 NOT_LP64(0); | |
381 const static uintptr_t size_mask_in_place = | |
382 (address_word)size_mask << size_shift; | |
383 | |
384 #ifdef _LP64 | |
385 static markOop cms_free_prototype() { | |
386 return markOop(((intptr_t)prototype() & ~cms_mask_in_place) | | |
387 ((cms_free_chunk_pattern & cms_mask) << cms_shift)); | |
388 } | |
389 uintptr_t cms_encoding() const { | |
390 return mask_bits(value() >> cms_shift, cms_mask); | |
391 } | |
392 bool is_cms_free_chunk() const { | |
393 return is_neutral() && | |
394 (cms_encoding() & cms_free_chunk_pattern) == cms_free_chunk_pattern; | |
395 } | |
396 | |
397 size_t get_size() const { return (size_t)(value() >> size_shift); } | |
398 static markOop set_size_and_free(size_t size) { | |
399 assert((size & ~size_mask) == 0, "shouldn't overflow size field"); | |
400 return markOop(((intptr_t)cms_free_prototype() & ~size_mask_in_place) | | |
401 (((intptr_t)size & size_mask) << size_shift)); | |
402 } | |
403 #endif // _LP64 | |
0 | 404 }; |
1972 | 405 |
406 #endif // SHARE_VM_OOPS_MARKOOP_HPP |