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 _table = new CodeRootSetTable(SmallSize); 201 } 202 203 void CodeRootSetTable::purge_list_append(CodeRootSetTable* table) { 204 for (;;) { 205 table->_purge_next = _purge_list; 206 CodeRootSetTable* old = (CodeRootSetTable*) Atomic::cmpxchg_ptr(table, &_purge_list, table->_purge_next); 207 if (old == table->_purge_next) { 208 break; 209 } 210 } 211 } 212 213 void CodeRootSetTable::purge() { 214 CodeRootSetTable* table = _purge_list; 215 _purge_list = NULL; 216 while (table != NULL) { 217 CodeRootSetTable* to_purge = table; 218 table = table->_purge_next; 219 delete to_purge; 220 } 221 } 222 223 void G1CodeRootSet::move_to_large() { 224 CodeRootSetTable* temp = new CodeRootSetTable(LargeSize); 225 226 _table->copy_to(temp); 227 228 CodeRootSetTable::purge_list_append(_table); 229 230 OrderAccess::release_store_ptr(&_table, temp); 231 } 232 233 234 void G1CodeRootSet::purge() { 235 CodeRootSetTable::purge(); 236 } 237 238 size_t G1CodeRootSet::static_mem_size() { 239 return CodeRootSetTable::static_mem_size(); 240 } 241 242 void G1CodeRootSet::add(nmethod* method) { 243 bool added = false; 244 if (is_empty()) { 245 allocate_small_table(); 246 } 247 added = _table->add(method); 248 if (_length == Threshold) { 249 move_to_large(); 250 } 251 if (added) { 252 ++_length; 253 } 254 } 255 256 bool G1CodeRootSet::remove(nmethod* method) { 257 bool removed = false; 258 if (_table != NULL) { 259 removed = _table->remove(method); 260 } 261 if (removed) { 262 _length--; 263 if (_length == 0) { 264 clear(); 265 } 266 } 267 return removed; 268 } 269 270 bool G1CodeRootSet::contains(nmethod* method) { 271 CodeRootSetTable* table = load_acquire_table(); 272 if (table != NULL) { 273 return table->contains(method); 274 } 275 return false; 276 } 277 278 void G1CodeRootSet::clear() { 279 delete _table; 280 _table = NULL; 281 _length = 0; 282 } 283 284 size_t G1CodeRootSet::mem_size() { 285 return sizeof(*this) + 286 (_table != NULL ? sizeof(CodeRootSetTable) + _table->entry_size() * _length : 0); 287 } 288 289 void G1CodeRootSet::nmethods_do(CodeBlobClosure* blk) const { 290 if (_table != NULL) { 291 _table->nmethods_do(blk); 292 } 293 } 294 295 class CleanCallback : public StackObj { 296 class PointsIntoHRDetectionClosure : public OopClosure { 297 HeapRegion* _hr; 298 public: 299 bool _points_into; 300 PointsIntoHRDetectionClosure(HeapRegion* hr) : _hr(hr), _points_into(false) {} 301 302 void do_oop(narrowOop* o) { 303 do_oop_work(o); 304 } 305 306 void do_oop(oop* o) { 307 do_oop_work(o); 308 } 309 310 template <typename T> 311 void do_oop_work(T* p) { 312 if (_hr->is_in(oopDesc::load_decode_heap_oop(p))) { 313 _points_into = true; 314 } 315 } 316 }; 317 318 PointsIntoHRDetectionClosure _detector; 319 CodeBlobToOopClosure _blobs; 320 321 public: 322 CleanCallback(HeapRegion* hr) : _detector(hr), _blobs(&_detector, !CodeBlobToOopClosure::FixRelocations) {} 323 324 bool operator() (nmethod* nm) { 325 _detector._points_into = false; 326 _blobs.do_code_blob(nm); 327 return !_detector._points_into; 328 } 329 }; 330 331 void G1CodeRootSet::clean(HeapRegion* owner) { 332 CleanCallback should_clean(owner); 333 if (_table != NULL) { 334 int removed = _table->remove_if(should_clean); 335 assert((size_t)removed <= _length, "impossible"); 336 _length -= removed; 337 } 338 if (_length == 0) { 339 clear(); 340 } 341 } 342 343 #ifndef PRODUCT 344 345 class G1CodeRootSetTest { 346 public: 347 static void test() { 348 { 349 G1CodeRootSet set1; 350 assert(set1.is_empty(), "Code root set must be initially empty but is not."); 351 352 assert(G1CodeRootSet::static_mem_size() == sizeof(void*), 353 err_msg("The code root set's static memory usage is incorrect, "SIZE_FORMAT" bytes", G1CodeRootSet::static_mem_size())); 354 355 set1.add((nmethod*)1); 356 assert(set1.length() == 1, err_msg("Added exactly one element, but set contains " 357 SIZE_FORMAT" elements", set1.length())); 358 359 const size_t num_to_add = (size_t)G1CodeRootSet::Threshold + 1; 360 361 for (size_t i = 1; i <= num_to_add; i++) { 362 set1.add((nmethod*)1); 363 } 364 assert(set1.length() == 1, 365 err_msg("Duplicate detection should not have increased the set size but " 366 "is "SIZE_FORMAT, set1.length())); 367 368 for (size_t i = 2; i <= num_to_add; i++) { 369 set1.add((nmethod*)(uintptr_t)(i)); 370 } 371 assert(set1.length() == num_to_add, 372 err_msg("After adding in total "SIZE_FORMAT" distinct code roots, they " 373 "need to be in the set, but there are only "SIZE_FORMAT, 374 num_to_add, set1.length())); 375 376 assert(CodeRootSetTable::_purge_list != NULL, "should have grown to large hashtable"); 377 378 size_t num_popped = 0; 379 for (size_t i = 1; i <= num_to_add; i++) { 380 bool removed = set1.remove((nmethod*)i); 381 if (removed) { 382 num_popped += 1; 383 } else { 384 break; 385 } 386 } 387 assert(num_popped == num_to_add, 388 err_msg("Managed to pop "SIZE_FORMAT" code roots, but only "SIZE_FORMAT" " 389 "were added", num_popped, num_to_add)); 390 assert(CodeRootSetTable::_purge_list != NULL, "should have grown to large hashtable"); 391 392 G1CodeRootSet::purge(); 393 394 assert(CodeRootSetTable::_purge_list == NULL, "should have purged old small tables"); 395 396 } 397 398 } 399 }; 400 401 void TestCodeCacheRemSet_test() { 402 G1CodeRootSetTest::test(); 403 } 404 405 #endif