1 /*
2 * Copyright (c) 2014, 2015, 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 #include "precompiled.hpp"
26 #include "code/codeCache.hpp"
27 #include "code/nmethod.hpp"
28 #include "gc/g1/g1CodeCacheRemSet.hpp"
29 #include "gc/g1/heapRegion.hpp"
30 #include "memory/heap.hpp"
31 #include "memory/iterator.hpp"
32 #include "oops/oop.inline.hpp"
33 #include "utilities/hashtable.inline.hpp"
34 #include "utilities/stack.inline.hpp"
35
36 class CodeRootSetTable : public Hashtable<nmethod*, mtGC> {
37 friend class G1CodeRootSetTest;
38 typedef HashtableEntry<nmethod*, mtGC> Entry;
39
40 static CodeRootSetTable* volatile _purge_list;
41
42 CodeRootSetTable* _purge_next;
43
44 unsigned int compute_hash(nmethod* nm) {
45 uintptr_t hash = (uintptr_t)nm;
46 return hash ^ (hash >> 7); // code heap blocks are 128byte aligned
47 }
48
49 void remove_entry(Entry* e, Entry* previous);
50 Entry* new_entry(nmethod* nm);
51
52 public:
53 CodeRootSetTable(int size) : Hashtable<nmethod*, mtGC>(size, sizeof(Entry)), _purge_next(NULL) {}
54 ~CodeRootSetTable();
55
56 // Needs to be protected locks
57 bool add(nmethod* nm);
58 bool remove(nmethod* nm);
59
60 // Can be called without locking
61 bool contains(nmethod* nm);
62
63 int entry_size() const { return BasicHashtable<mtGC>::entry_size(); }
64
65 void copy_to(CodeRootSetTable* new_table);
66 void nmethods_do(CodeBlobClosure* blk);
67
68 template<typename CB>
69 int remove_if(CB& should_remove);
70
71 static void purge_list_append(CodeRootSetTable* tbl);
72 static void purge();
73
74 static size_t static_mem_size() {
75 return sizeof(_purge_list);
76 }
77 };
78
79 CodeRootSetTable* volatile CodeRootSetTable::_purge_list = NULL;
80
81 CodeRootSetTable::Entry* CodeRootSetTable::new_entry(nmethod* nm) {
82 unsigned int hash = compute_hash(nm);
83 Entry* entry = (Entry*) new_entry_free_list();
84 if (entry == NULL) {
85 entry = (Entry*) NEW_C_HEAP_ARRAY2(char, entry_size(), mtGC, CURRENT_PC);
86 }
87 entry->set_next(NULL);
88 entry->set_hash(hash);
89 entry->set_literal(nm);
90 return entry;
91 }
92
93 void CodeRootSetTable::remove_entry(Entry* e, Entry* previous) {
94 int index = hash_to_index(e->hash());
95 assert((e == bucket(index)) == (previous == NULL), "if e is the first entry then previous should be null");
96
97 if (previous == NULL) {
98 set_entry(index, e->next());
99 } else {
100 previous->set_next(e->next());
101 }
102 free_entry(e);
103 }
104
105 CodeRootSetTable::~CodeRootSetTable() {
106 for (int index = 0; index < table_size(); ++index) {
107 for (Entry* e = bucket(index); e != NULL; ) {
108 Entry* to_remove = e;
109 // read next before freeing.
110 e = e->next();
111 unlink_entry(to_remove);
112 FREE_C_HEAP_ARRAY(char, to_remove);
113 }
114 }
115 assert(number_of_entries() == 0, "should have removed all entries");
116 free_buckets();
117 for (BasicHashtableEntry<mtGC>* e = new_entry_free_list(); e != NULL; e = new_entry_free_list()) {
118 FREE_C_HEAP_ARRAY(char, e);
119 }
120 }
121
122 bool CodeRootSetTable::add(nmethod* nm) {
123 if (!contains(nm)) {
124 Entry* e = new_entry(nm);
125 int index = hash_to_index(e->hash());
126 add_entry(index, e);
127 return true;
128 }
129 return false;
130 }
131
132 bool CodeRootSetTable::contains(nmethod* nm) {
133 int index = hash_to_index(compute_hash(nm));
134 for (Entry* e = bucket(index); e != NULL; e = e->next()) {
135 if (e->literal() == nm) {
136 return true;
137 }
138 }
139 return false;
140 }
141
142 bool CodeRootSetTable::remove(nmethod* nm) {
143 int index = hash_to_index(compute_hash(nm));
144 Entry* previous = NULL;
145 for (Entry* e = bucket(index); e != NULL; previous = e, e = e->next()) {
146 if (e->literal() == nm) {
147 remove_entry(e, previous);
148 return true;
149 }
150 }
151 return false;
152 }
153
154 void CodeRootSetTable::copy_to(CodeRootSetTable* new_table) {
155 for (int index = 0; index < table_size(); ++index) {
156 for (Entry* e = bucket(index); e != NULL; e = e->next()) {
157 new_table->add(e->literal());
158 }
159 }
160 new_table->copy_freelist(this);
161 }
162
163 void CodeRootSetTable::nmethods_do(CodeBlobClosure* blk) {
164 for (int index = 0; index < table_size(); ++index) {
165 for (Entry* e = bucket(index); e != NULL; e = e->next()) {
166 blk->do_code_blob(e->literal());
167 }
168 }
169 }
170
171 template<typename CB>
172 int CodeRootSetTable::remove_if(CB& should_remove) {
173 int num_removed = 0;
174 for (int index = 0; index < table_size(); ++index) {
175 Entry* previous = NULL;
176 Entry* e = bucket(index);
177 while (e != NULL) {
178 Entry* next = e->next();
179 if (should_remove(e->literal())) {
180 remove_entry(e, previous);
181 ++num_removed;
182 } else {
183 previous = e;
184 }
185 e = next;
186 }
187 }
188 return num_removed;
189 }
190
191 G1CodeRootSet::~G1CodeRootSet() {
192 delete _table;
193 }
194
195 CodeRootSetTable* G1CodeRootSet::load_acquire_table() {
196 return (CodeRootSetTable*) OrderAccess::load_ptr_acquire(&_table);
197 }
198
199 void G1CodeRootSet::allocate_small_table() {
200 CodeRootSetTable* temp = new CodeRootSetTable(SmallSize);
201
202 OrderAccess::release_store_ptr(&_table, temp);
203 }
204
205 void CodeRootSetTable::purge_list_append(CodeRootSetTable* table) {
206 for (;;) {
207 table->_purge_next = _purge_list;
208 CodeRootSetTable* old = (CodeRootSetTable*) Atomic::cmpxchg_ptr(table, &_purge_list, table->_purge_next);
209 if (old == table->_purge_next) {
210 break;
211 }
212 }
213 }
214
215 void CodeRootSetTable::purge() {
216 CodeRootSetTable* table = _purge_list;
217 _purge_list = NULL;
218 while (table != NULL) {
219 CodeRootSetTable* to_purge = table;
220 table = table->_purge_next;
221 delete to_purge;
222 }
223 }
224
225 void G1CodeRootSet::move_to_large() {
226 CodeRootSetTable* temp = new CodeRootSetTable(LargeSize);
227
228 _table->copy_to(temp);
229
230 CodeRootSetTable::purge_list_append(_table);
231
232 OrderAccess::release_store_ptr(&_table, temp);
233 }
234
235
236 void G1CodeRootSet::purge() {
237 CodeRootSetTable::purge();
238 }
239
240 size_t G1CodeRootSet::static_mem_size() {
241 return CodeRootSetTable::static_mem_size();
242 }
243
244 void G1CodeRootSet::add(nmethod* method) {
245 bool added = false;
246 if (is_empty()) {
247 allocate_small_table();
248 }
249 added = _table->add(method);
250 if (_length == Threshold) {
251 move_to_large();
252 }
253 if (added) {
254 ++_length;
255 }
256 }
257
258 bool G1CodeRootSet::remove(nmethod* method) {
259 bool removed = false;
260 if (_table != NULL) {
261 removed = _table->remove(method);
262 }
263 if (removed) {
264 _length--;
265 if (_length == 0) {
266 clear();
267 }
268 }
269 return removed;
270 }
271
272 bool G1CodeRootSet::contains(nmethod* method) {
273 CodeRootSetTable* table = load_acquire_table();
274 if (table != NULL) {
275 return table->contains(method);
276 }
277 return false;
278 }
279
280 void G1CodeRootSet::clear() {
281 delete _table;
282 _table = NULL;
283 _length = 0;
284 }
285
286 size_t G1CodeRootSet::mem_size() {
287 return sizeof(*this) +
288 (_table != NULL ? sizeof(CodeRootSetTable) + _table->entry_size() * _length : 0);
289 }
290
291 void G1CodeRootSet::nmethods_do(CodeBlobClosure* blk) const {
292 if (_table != NULL) {
293 _table->nmethods_do(blk);
294 }
295 }
296
297 class CleanCallback : public StackObj {
298 class PointsIntoHRDetectionClosure : public OopClosure {
299 HeapRegion* _hr;
300 public:
301 bool _points_into;
302 PointsIntoHRDetectionClosure(HeapRegion* hr) : _hr(hr), _points_into(false) {}
303
304 void do_oop(narrowOop* o) {
305 do_oop_work(o);
306 }
307
308 void do_oop(oop* o) {
309 do_oop_work(o);
310 }
311
312 template <typename T>
313 void do_oop_work(T* p) {
314 if (_hr->is_in(oopDesc::load_decode_heap_oop(p))) {
315 _points_into = true;
316 }
317 }
318 };
319
320 PointsIntoHRDetectionClosure _detector;
321 CodeBlobToOopClosure _blobs;
322
323 public:
324 CleanCallback(HeapRegion* hr) : _detector(hr), _blobs(&_detector, !CodeBlobToOopClosure::FixRelocations) {}
325
326 bool operator() (nmethod* nm) {
327 _detector._points_into = false;
328 _blobs.do_code_blob(nm);
329 return !_detector._points_into;
330 }
331 };
332
333 void G1CodeRootSet::clean(HeapRegion* owner) {
334 CleanCallback should_clean(owner);
335 if (_table != NULL) {
336 int removed = _table->remove_if(should_clean);
337 assert((size_t)removed <= _length, "impossible");
338 _length -= removed;
339 }
340 if (_length == 0) {
341 clear();
342 }
343 }
344
345 #ifndef PRODUCT
346
347 class G1CodeRootSetTest {
348 public:
349 static void test() {
350 {
351 G1CodeRootSet set1;
352 assert(set1.is_empty(), "Code root set must be initially empty but is not.");
353
354 assert(G1CodeRootSet::static_mem_size() == sizeof(void*),
355 "The code root set's static memory usage is incorrect, " SIZE_FORMAT " bytes", G1CodeRootSet::static_mem_size());
356
357 set1.add((nmethod*)1);
358 assert(set1.length() == 1, "Added exactly one element, but set contains "
359 SIZE_FORMAT " elements", set1.length());
360
361 const size_t num_to_add = (size_t)G1CodeRootSet::Threshold + 1;
362
363 for (size_t i = 1; i <= num_to_add; i++) {
364 set1.add((nmethod*)1);
365 }
366 assert(set1.length() == 1,
367 "Duplicate detection should not have increased the set size but "
368 "is " SIZE_FORMAT, set1.length());
369
370 for (size_t i = 2; i <= num_to_add; i++) {
371 set1.add((nmethod*)(uintptr_t)(i));
372 }
373 assert(set1.length() == num_to_add,
374 "After adding in total " SIZE_FORMAT " distinct code roots, they "
375 "need to be in the set, but there are only " SIZE_FORMAT,
376 num_to_add, set1.length());
377
378 assert(CodeRootSetTable::_purge_list != NULL, "should have grown to large hashtable");
379
380 size_t num_popped = 0;
381 for (size_t i = 1; i <= num_to_add; i++) {
382 bool removed = set1.remove((nmethod*)i);
383 if (removed) {
384 num_popped += 1;
385 } else {
386 break;
387 }
388 }
389 assert(num_popped == num_to_add,
390 "Managed to pop " SIZE_FORMAT " code roots, but only " SIZE_FORMAT " "
391 "were added", num_popped, num_to_add);
392 assert(CodeRootSetTable::_purge_list != NULL, "should have grown to large hashtable");
393
394 G1CodeRootSet::purge();
395
396 assert(CodeRootSetTable::_purge_list == NULL, "should have purged old small tables");
397
398 }
399
400 }
401 };
402
403 void TestCodeCacheRemSet_test() {
404 G1CodeRootSetTest::test();
405 }
406
407 #endif