Wed, 11 Aug 2010 05:51:21 -0700
6976186: integrate Shark HotSpot changes
Summary: Shark is a JIT compiler for Zero that uses the LLVM compiler infrastructure.
Reviewed-by: kvn, twisti
Contributed-by: Gary Benson <gbenson@redhat.com>
1 /*
2 * Copyright (c) 2000, 2010, 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.
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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
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23 */
25 // This kind of "BarrierSet" allows a "CollectedHeap" to detect and
26 // enumerate ref fields that have been modified (since the last
27 // enumeration.)
29 // As it currently stands, this barrier is *imprecise*: when a ref field in
30 // an object "o" is modified, the card table entry for the card containing
31 // the head of "o" is dirtied, not necessarily the card containing the
32 // modified field itself. For object arrays, however, the barrier *is*
33 // precise; only the card containing the modified element is dirtied.
34 // Any MemRegionClosures used to scan dirty cards should take these
35 // considerations into account.
37 class Generation;
38 class OopsInGenClosure;
39 class DirtyCardToOopClosure;
41 class CardTableModRefBS: public ModRefBarrierSet {
42 // Some classes get to look at some private stuff.
43 friend class BytecodeInterpreter;
44 friend class VMStructs;
45 friend class CardTableRS;
46 friend class CheckForUnmarkedOops; // Needs access to raw card bytes.
47 friend class SharkBuilder;
48 #ifndef PRODUCT
49 // For debugging.
50 friend class GuaranteeNotModClosure;
51 #endif
52 protected:
54 enum CardValues {
55 clean_card = -1,
56 // The mask contains zeros in places for all other values.
57 clean_card_mask = clean_card - 31,
59 dirty_card = 0,
60 precleaned_card = 1,
61 claimed_card = 2,
62 deferred_card = 4,
63 last_card = 8,
64 CT_MR_BS_last_reserved = 16
65 };
67 // dirty and precleaned are equivalent wrt younger_refs_iter.
68 static bool card_is_dirty_wrt_gen_iter(jbyte cv) {
69 return cv == dirty_card || cv == precleaned_card;
70 }
72 // Returns "true" iff the value "cv" will cause the card containing it
73 // to be scanned in the current traversal. May be overridden by
74 // subtypes.
75 virtual bool card_will_be_scanned(jbyte cv) {
76 return CardTableModRefBS::card_is_dirty_wrt_gen_iter(cv);
77 }
79 // Returns "true" iff the value "cv" may have represented a dirty card at
80 // some point.
81 virtual bool card_may_have_been_dirty(jbyte cv) {
82 return card_is_dirty_wrt_gen_iter(cv);
83 }
85 // The declaration order of these const fields is important; see the
86 // constructor before changing.
87 const MemRegion _whole_heap; // the region covered by the card table
88 const size_t _guard_index; // index of very last element in the card
89 // table; it is set to a guard value
90 // (last_card) and should never be modified
91 const size_t _last_valid_index; // index of the last valid element
92 const size_t _page_size; // page size used when mapping _byte_map
93 const size_t _byte_map_size; // in bytes
94 jbyte* _byte_map; // the card marking array
96 int _cur_covered_regions;
97 // The covered regions should be in address order.
98 MemRegion* _covered;
99 // The committed regions correspond one-to-one to the covered regions.
100 // They represent the card-table memory that has been committed to service
101 // the corresponding covered region. It may be that committed region for
102 // one covered region corresponds to a larger region because of page-size
103 // roundings. Thus, a committed region for one covered region may
104 // actually extend onto the card-table space for the next covered region.
105 MemRegion* _committed;
107 // The last card is a guard card, and we commit the page for it so
108 // we can use the card for verification purposes. We make sure we never
109 // uncommit the MemRegion for that page.
110 MemRegion _guard_region;
112 protected:
113 // Initialization utilities; covered_words is the size of the covered region
114 // in, um, words.
115 inline size_t cards_required(size_t covered_words);
116 inline size_t compute_byte_map_size();
118 // Finds and return the index of the region, if any, to which the given
119 // region would be contiguous. If none exists, assign a new region and
120 // returns its index. Requires that no more than the maximum number of
121 // covered regions defined in the constructor are ever in use.
122 int find_covering_region_by_base(HeapWord* base);
124 // Same as above, but finds the region containing the given address
125 // instead of starting at a given base address.
126 int find_covering_region_containing(HeapWord* addr);
128 // Resize one of the regions covered by the remembered set.
129 void resize_covered_region(MemRegion new_region);
131 // Returns the leftmost end of a committed region corresponding to a
132 // covered region before covered region "ind", or else "NULL" if "ind" is
133 // the first covered region.
134 HeapWord* largest_prev_committed_end(int ind) const;
136 // Returns the part of the region mr that doesn't intersect with
137 // any committed region other than self. Used to prevent uncommitting
138 // regions that are also committed by other regions. Also protects
139 // against uncommitting the guard region.
140 MemRegion committed_unique_to_self(int self, MemRegion mr) const;
142 // Mapping from address to card marking array entry
143 jbyte* byte_for(const void* p) const {
144 assert(_whole_heap.contains(p),
145 "out of bounds access to card marking array");
146 jbyte* result = &byte_map_base[uintptr_t(p) >> card_shift];
147 assert(result >= _byte_map && result < _byte_map + _byte_map_size,
148 "out of bounds accessor for card marking array");
149 return result;
150 }
152 // The card table byte one after the card marking array
153 // entry for argument address. Typically used for higher bounds
154 // for loops iterating through the card table.
155 jbyte* byte_after(const void* p) const {
156 return byte_for(p) + 1;
157 }
159 // Iterate over the portion of the card-table which covers the given
160 // region mr in the given space and apply cl to any dirty sub-regions
161 // of mr. cl and dcto_cl must either be the same closure or cl must
162 // wrap dcto_cl. Both are required - neither may be NULL. Also, dcto_cl
163 // may be modified. Note that this function will operate in a parallel
164 // mode if worker threads are available.
165 void non_clean_card_iterate(Space* sp, MemRegion mr,
166 DirtyCardToOopClosure* dcto_cl,
167 MemRegionClosure* cl,
168 bool clear);
170 // Utility function used to implement the other versions below.
171 void non_clean_card_iterate_work(MemRegion mr, MemRegionClosure* cl,
172 bool clear);
174 void par_non_clean_card_iterate_work(Space* sp, MemRegion mr,
175 DirtyCardToOopClosure* dcto_cl,
176 MemRegionClosure* cl,
177 bool clear,
178 int n_threads);
180 // Dirty the bytes corresponding to "mr" (not all of which must be
181 // covered.)
182 void dirty_MemRegion(MemRegion mr);
184 // Clear (to clean_card) the bytes entirely contained within "mr" (not
185 // all of which must be covered.)
186 void clear_MemRegion(MemRegion mr);
188 // *** Support for parallel card scanning.
190 enum SomeConstantsForParallelism {
191 StridesPerThread = 2,
192 CardsPerStrideChunk = 256
193 };
195 // This is an array, one element per covered region of the card table.
196 // Each entry is itself an array, with one element per chunk in the
197 // covered region. Each entry of these arrays is the lowest non-clean
198 // card of the corresponding chunk containing part of an object from the
199 // previous chunk, or else NULL.
200 typedef jbyte* CardPtr;
201 typedef CardPtr* CardArr;
202 CardArr* _lowest_non_clean;
203 size_t* _lowest_non_clean_chunk_size;
204 uintptr_t* _lowest_non_clean_base_chunk_index;
205 int* _last_LNC_resizing_collection;
207 // Initializes "lowest_non_clean" to point to the array for the region
208 // covering "sp", and "lowest_non_clean_base_chunk_index" to the chunk
209 // index of the corresponding to the first element of that array.
210 // Ensures that these arrays are of sufficient size, allocating if necessary.
211 // May be called by several threads concurrently.
212 void get_LNC_array_for_space(Space* sp,
213 jbyte**& lowest_non_clean,
214 uintptr_t& lowest_non_clean_base_chunk_index,
215 size_t& lowest_non_clean_chunk_size);
217 // Returns the number of chunks necessary to cover "mr".
218 size_t chunks_to_cover(MemRegion mr) {
219 return (size_t)(addr_to_chunk_index(mr.last()) -
220 addr_to_chunk_index(mr.start()) + 1);
221 }
223 // Returns the index of the chunk in a stride which
224 // covers the given address.
225 uintptr_t addr_to_chunk_index(const void* addr) {
226 uintptr_t card = (uintptr_t) byte_for(addr);
227 return card / CardsPerStrideChunk;
228 }
230 // Apply cl, which must either itself apply dcto_cl or be dcto_cl,
231 // to the cards in the stride (of n_strides) within the given space.
232 void process_stride(Space* sp,
233 MemRegion used,
234 jint stride, int n_strides,
235 DirtyCardToOopClosure* dcto_cl,
236 MemRegionClosure* cl,
237 bool clear,
238 jbyte** lowest_non_clean,
239 uintptr_t lowest_non_clean_base_chunk_index,
240 size_t lowest_non_clean_chunk_size);
242 // Makes sure that chunk boundaries are handled appropriately, by
243 // adjusting the min_done of dcto_cl, and by using a special card-table
244 // value to indicate how min_done should be set.
245 void process_chunk_boundaries(Space* sp,
246 DirtyCardToOopClosure* dcto_cl,
247 MemRegion chunk_mr,
248 MemRegion used,
249 jbyte** lowest_non_clean,
250 uintptr_t lowest_non_clean_base_chunk_index,
251 size_t lowest_non_clean_chunk_size);
253 public:
254 // Constants
255 enum SomePublicConstants {
256 card_shift = 9,
257 card_size = 1 << card_shift,
258 card_size_in_words = card_size / sizeof(HeapWord)
259 };
261 static int clean_card_val() { return clean_card; }
262 static int clean_card_mask_val() { return clean_card_mask; }
263 static int dirty_card_val() { return dirty_card; }
264 static int claimed_card_val() { return claimed_card; }
265 static int precleaned_card_val() { return precleaned_card; }
266 static int deferred_card_val() { return deferred_card; }
268 // For RTTI simulation.
269 bool is_a(BarrierSet::Name bsn) {
270 return bsn == BarrierSet::CardTableModRef || ModRefBarrierSet::is_a(bsn);
271 }
273 CardTableModRefBS(MemRegion whole_heap, int max_covered_regions);
275 // *** Barrier set functions.
277 bool has_write_ref_pre_barrier() { return false; }
279 inline bool write_ref_needs_barrier(void* field, oop new_val) {
280 // Note that this assumes the perm gen is the highest generation
281 // in the address space
282 return new_val != NULL && !new_val->is_perm();
283 }
285 // Record a reference update. Note that these versions are precise!
286 // The scanning code has to handle the fact that the write barrier may be
287 // either precise or imprecise. We make non-virtual inline variants of
288 // these functions here for performance.
289 protected:
290 void write_ref_field_work(oop obj, size_t offset, oop newVal);
291 virtual void write_ref_field_work(void* field, oop newVal);
292 public:
294 bool has_write_ref_array_opt() { return true; }
295 bool has_write_region_opt() { return true; }
297 inline void inline_write_region(MemRegion mr) {
298 dirty_MemRegion(mr);
299 }
300 protected:
301 void write_region_work(MemRegion mr) {
302 inline_write_region(mr);
303 }
304 public:
306 inline void inline_write_ref_array(MemRegion mr) {
307 dirty_MemRegion(mr);
308 }
309 protected:
310 void write_ref_array_work(MemRegion mr) {
311 inline_write_ref_array(mr);
312 }
313 public:
315 bool is_aligned(HeapWord* addr) {
316 return is_card_aligned(addr);
317 }
319 // *** Card-table-barrier-specific things.
321 template <class T> inline void inline_write_ref_field_pre(T* field, oop newVal) {}
323 template <class T> inline void inline_write_ref_field(T* field, oop newVal) {
324 jbyte* byte = byte_for((void*)field);
325 *byte = dirty_card;
326 }
328 // These are used by G1, when it uses the card table as a temporary data
329 // structure for card claiming.
330 bool is_card_dirty(size_t card_index) {
331 return _byte_map[card_index] == dirty_card_val();
332 }
334 void mark_card_dirty(size_t card_index) {
335 _byte_map[card_index] = dirty_card_val();
336 }
338 bool is_card_claimed(size_t card_index) {
339 jbyte val = _byte_map[card_index];
340 return (val & (clean_card_mask_val() | claimed_card_val())) == claimed_card_val();
341 }
343 void set_card_claimed(size_t card_index) {
344 jbyte val = _byte_map[card_index];
345 if (val == clean_card_val()) {
346 val = (jbyte)claimed_card_val();
347 } else {
348 val |= (jbyte)claimed_card_val();
349 }
350 _byte_map[card_index] = val;
351 }
353 bool claim_card(size_t card_index);
355 bool is_card_clean(size_t card_index) {
356 return _byte_map[card_index] == clean_card_val();
357 }
359 bool is_card_deferred(size_t card_index) {
360 jbyte val = _byte_map[card_index];
361 return (val & (clean_card_mask_val() | deferred_card_val())) == deferred_card_val();
362 }
364 bool mark_card_deferred(size_t card_index);
366 // Card marking array base (adjusted for heap low boundary)
367 // This would be the 0th element of _byte_map, if the heap started at 0x0.
368 // But since the heap starts at some higher address, this points to somewhere
369 // before the beginning of the actual _byte_map.
370 jbyte* byte_map_base;
372 // Return true if "p" is at the start of a card.
373 bool is_card_aligned(HeapWord* p) {
374 jbyte* pcard = byte_for(p);
375 return (addr_for(pcard) == p);
376 }
378 // The kinds of precision a CardTableModRefBS may offer.
379 enum PrecisionStyle {
380 Precise,
381 ObjHeadPreciseArray
382 };
384 // Tells what style of precision this card table offers.
385 PrecisionStyle precision() {
386 return ObjHeadPreciseArray; // Only one supported for now.
387 }
389 // ModRefBS functions.
390 virtual void invalidate(MemRegion mr, bool whole_heap = false);
391 void clear(MemRegion mr);
392 void dirty(MemRegion mr);
393 void mod_oop_in_space_iterate(Space* sp, OopClosure* cl,
394 bool clear = false,
395 bool before_save_marks = false);
397 // *** Card-table-RemSet-specific things.
399 // Invoke "cl.do_MemRegion" on a set of MemRegions that collectively
400 // includes all the modified cards (expressing each card as a
401 // MemRegion). Thus, several modified cards may be lumped into one
402 // region. The regions are non-overlapping, and are visited in
403 // *decreasing* address order. (This order aids with imprecise card
404 // marking, where a dirty card may cause scanning, and summarization
405 // marking, of objects that extend onto subsequent cards.)
406 // If "clear" is true, the card is (conceptually) marked unmodified before
407 // applying the closure.
408 void mod_card_iterate(MemRegionClosure* cl, bool clear = false) {
409 non_clean_card_iterate_work(_whole_heap, cl, clear);
410 }
412 // Like the "mod_cards_iterate" above, except only invokes the closure
413 // for cards within the MemRegion "mr" (which is required to be
414 // card-aligned and sized.)
415 void mod_card_iterate(MemRegion mr, MemRegionClosure* cl,
416 bool clear = false) {
417 non_clean_card_iterate_work(mr, cl, clear);
418 }
420 static uintx ct_max_alignment_constraint();
422 // Apply closure "cl" to the dirty cards containing some part of
423 // MemRegion "mr".
424 void dirty_card_iterate(MemRegion mr, MemRegionClosure* cl);
426 // Return the MemRegion corresponding to the first maximal run
427 // of dirty cards lying completely within MemRegion mr.
428 // If reset is "true", then sets those card table entries to the given
429 // value.
430 MemRegion dirty_card_range_after_reset(MemRegion mr, bool reset,
431 int reset_val);
433 // Set all the dirty cards in the given region to precleaned state.
434 void preclean_dirty_cards(MemRegion mr);
436 // Provide read-only access to the card table array.
437 const jbyte* byte_for_const(const void* p) const {
438 return byte_for(p);
439 }
440 const jbyte* byte_after_const(const void* p) const {
441 return byte_after(p);
442 }
444 // Mapping from card marking array entry to address of first word
445 HeapWord* addr_for(const jbyte* p) const {
446 assert(p >= _byte_map && p < _byte_map + _byte_map_size,
447 "out of bounds access to card marking array");
448 size_t delta = pointer_delta(p, byte_map_base, sizeof(jbyte));
449 HeapWord* result = (HeapWord*) (delta << card_shift);
450 assert(_whole_heap.contains(result),
451 "out of bounds accessor from card marking array");
452 return result;
453 }
455 // Mapping from address to card marking array index.
456 size_t index_for(void* p) {
457 assert(_whole_heap.contains(p),
458 "out of bounds access to card marking array");
459 return byte_for(p) - _byte_map;
460 }
462 const jbyte* byte_for_index(const size_t card_index) const {
463 return _byte_map + card_index;
464 }
466 void verify();
467 void verify_guard();
469 void verify_clean_region(MemRegion mr) PRODUCT_RETURN;
470 void verify_dirty_region(MemRegion mr) PRODUCT_RETURN;
472 static size_t par_chunk_heapword_alignment() {
473 return CardsPerStrideChunk * card_size_in_words;
474 }
476 };
478 class CardTableRS;
480 // A specialization for the CardTableRS gen rem set.
481 class CardTableModRefBSForCTRS: public CardTableModRefBS {
482 CardTableRS* _rs;
483 protected:
484 bool card_will_be_scanned(jbyte cv);
485 bool card_may_have_been_dirty(jbyte cv);
486 public:
487 CardTableModRefBSForCTRS(MemRegion whole_heap,
488 int max_covered_regions) :
489 CardTableModRefBS(whole_heap, max_covered_regions) {}
491 void set_CTRS(CardTableRS* rs) { _rs = rs; }
492 };