1 /* 2 * Copyright (c) 1997, 2023, 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 "interpreter/bytecodeStream.hpp" 27 #include "interpreter/oopMapCache.hpp" 28 #include "logging/log.hpp" 29 #include "logging/logStream.hpp" 30 #include "memory/allocation.inline.hpp" 31 #include "memory/resourceArea.hpp" 32 #include "oops/generateOopMap.hpp" 33 #include "oops/oop.inline.hpp" 34 #include "runtime/atomic.hpp" 35 #include "runtime/handles.inline.hpp" 36 #include "runtime/safepoint.hpp" 37 #include "runtime/signature.hpp" 38 39 class OopMapCacheEntry: private InterpreterOopMap { 40 friend class InterpreterOopMap; 41 friend class OopMapForCacheEntry; 42 friend class OopMapCache; 43 friend class VerifyClosure; 44 45 private: 46 OopMapCacheEntry* _next; 47 48 protected: 49 // Initialization 50 void fill(const methodHandle& method, int bci); 51 // fills the bit mask for native calls 52 void fill_for_native(const methodHandle& method); 53 void set_mask(CellTypeState* vars, CellTypeState* stack, int stack_top); 54 55 // Deallocate bit masks and initialize fields 56 void flush(); 57 58 static void deallocate(OopMapCacheEntry* const entry); 59 60 private: 61 void allocate_bit_mask(); // allocates the bit mask on C heap f necessary 62 void deallocate_bit_mask(); // allocates the bit mask on C heap f necessary 63 bool verify_mask(CellTypeState *vars, CellTypeState *stack, int max_locals, int stack_top); 64 65 public: 66 OopMapCacheEntry() : InterpreterOopMap() { 67 _next = nullptr; 68 #ifdef ASSERT 69 _resource_allocate_bit_mask = false; 70 #endif 71 } 72 }; 73 74 75 // Implementation of OopMapForCacheEntry 76 // (subclass of GenerateOopMap, initializes an OopMapCacheEntry for a given method and bci) 77 78 class OopMapForCacheEntry: public GenerateOopMap { 79 OopMapCacheEntry *_entry; 80 int _bci; 81 int _stack_top; 82 83 virtual bool report_results() const { return false; } 84 virtual bool possible_gc_point (BytecodeStream *bcs); 85 virtual void fill_stackmap_prolog (int nof_gc_points); 86 virtual void fill_stackmap_epilog (); 87 virtual void fill_stackmap_for_opcodes (BytecodeStream *bcs, 88 CellTypeState* vars, 89 CellTypeState* stack, 90 int stack_top); 91 virtual void fill_init_vars (GrowableArray<intptr_t> *init_vars); 92 93 public: 94 OopMapForCacheEntry(const methodHandle& method, int bci, OopMapCacheEntry *entry); 95 96 // Computes stack map for (method,bci) and initialize entry 97 bool compute_map(Thread* current); 98 int size(); 99 }; 100 101 102 OopMapForCacheEntry::OopMapForCacheEntry(const methodHandle& method, int bci, OopMapCacheEntry* entry) : GenerateOopMap(method) { 103 _bci = bci; 104 _entry = entry; 105 _stack_top = -1; 106 } 107 108 109 bool OopMapForCacheEntry::compute_map(Thread* current) { 110 assert(!method()->is_native(), "cannot compute oop map for native methods"); 111 // First check if it is a method where the stackmap is always empty 112 if (method()->code_size() == 0 || method()->max_locals() + method()->max_stack() == 0) { 113 _entry->set_mask_size(0); 114 } else { 115 ResourceMark rm; 116 if (!GenerateOopMap::compute_map(current)) { 117 fatal("Unrecoverable verification or out-of-memory error"); 118 return false; 119 } 120 result_for_basicblock(_bci); 121 } 122 return true; 123 } 124 125 126 bool OopMapForCacheEntry::possible_gc_point(BytecodeStream *bcs) { 127 return false; // We are not reporting any result. We call result_for_basicblock directly 128 } 129 130 131 void OopMapForCacheEntry::fill_stackmap_prolog(int nof_gc_points) { 132 // Do nothing 133 } 134 135 136 void OopMapForCacheEntry::fill_stackmap_epilog() { 137 // Do nothing 138 } 139 140 141 void OopMapForCacheEntry::fill_init_vars(GrowableArray<intptr_t> *init_vars) { 142 // Do nothing 143 } 144 145 146 void OopMapForCacheEntry::fill_stackmap_for_opcodes(BytecodeStream *bcs, 147 CellTypeState* vars, 148 CellTypeState* stack, 149 int stack_top) { 150 // Only interested in one specific bci 151 if (bcs->bci() == _bci) { 152 _entry->set_mask(vars, stack, stack_top); 153 _stack_top = stack_top; 154 } 155 } 156 157 158 int OopMapForCacheEntry::size() { 159 assert(_stack_top != -1, "compute_map must be called first"); 160 return ((method()->is_static()) ? 0 : 1) + method()->max_locals() + _stack_top; 161 } 162 163 164 // Implementation of InterpreterOopMap and OopMapCacheEntry 165 166 class VerifyClosure : public OffsetClosure { 167 private: 168 OopMapCacheEntry* _entry; 169 bool _failed; 170 171 public: 172 VerifyClosure(OopMapCacheEntry* entry) { _entry = entry; _failed = false; } 173 void offset_do(int offset) { if (!_entry->is_oop(offset)) _failed = true; } 174 bool failed() const { return _failed; } 175 }; 176 177 InterpreterOopMap::InterpreterOopMap() { 178 initialize(); 179 #ifdef ASSERT 180 _resource_allocate_bit_mask = true; 181 #endif 182 } 183 184 InterpreterOopMap::~InterpreterOopMap() { 185 // The expectation is that the bit mask was allocated 186 // last in this resource area. That would make the free of the 187 // bit_mask effective (see how FREE_RESOURCE_ARRAY does a free). 188 // If it was not allocated last, there is not a correctness problem 189 // but the space for the bit_mask is not freed. 190 assert(_resource_allocate_bit_mask, "Trying to free C heap space"); 191 if (mask_size() > small_mask_limit) { 192 FREE_RESOURCE_ARRAY(uintptr_t, _bit_mask[0], mask_word_size()); 193 } 194 } 195 196 bool InterpreterOopMap::is_empty() const { 197 bool result = _method == nullptr; 198 assert(_method != nullptr || (_bci == 0 && 199 (_mask_size == 0 || _mask_size == USHRT_MAX) && 200 _bit_mask[0] == 0), "Should be completely empty"); 201 return result; 202 } 203 204 void InterpreterOopMap::initialize() { 205 _method = nullptr; 206 _mask_size = USHRT_MAX; // This value should cause a failure quickly 207 _bci = 0; 208 _expression_stack_size = 0; 209 _num_oops = 0; 210 for (int i = 0; i < N; i++) _bit_mask[i] = 0; 211 } 212 213 void InterpreterOopMap::iterate_oop(OffsetClosure* oop_closure) const { 214 int n = number_of_entries(); 215 int word_index = 0; 216 uintptr_t value = 0; 217 uintptr_t mask = 0; 218 // iterate over entries 219 for (int i = 0; i < n; i++, mask <<= bits_per_entry) { 220 // get current word 221 if (mask == 0) { 222 value = bit_mask()[word_index++]; 223 mask = 1; 224 } 225 // test for oop 226 if ((value & (mask << oop_bit_number)) != 0) oop_closure->offset_do(i); 227 } 228 } 229 230 void InterpreterOopMap::print() const { 231 int n = number_of_entries(); 232 tty->print("oop map for "); 233 method()->print_value(); 234 tty->print(" @ %d = [%d] { ", bci(), n); 235 for (int i = 0; i < n; i++) { 236 if (is_dead(i)) tty->print("%d+ ", i); 237 else 238 if (is_oop(i)) tty->print("%d ", i); 239 } 240 tty->print_cr("}"); 241 } 242 243 class MaskFillerForNative: public NativeSignatureIterator { 244 private: 245 uintptr_t * _mask; // the bit mask to be filled 246 int _size; // the mask size in bits 247 248 void set_one(int i) { 249 i *= InterpreterOopMap::bits_per_entry; 250 assert(0 <= i && i < _size, "offset out of bounds"); 251 _mask[i / BitsPerWord] |= (((uintptr_t) 1 << InterpreterOopMap::oop_bit_number) << (i % BitsPerWord)); 252 } 253 254 public: 255 void pass_byte() { /* ignore */ } 256 void pass_short() { /* ignore */ } 257 void pass_int() { /* ignore */ } 258 void pass_long() { /* ignore */ } 259 void pass_float() { /* ignore */ } 260 void pass_double() { /* ignore */ } 261 void pass_object() { set_one(offset()); } 262 263 MaskFillerForNative(const methodHandle& method, uintptr_t* mask, int size) : NativeSignatureIterator(method) { 264 _mask = mask; 265 _size = size; 266 // initialize with 0 267 int i = (size + BitsPerWord - 1) / BitsPerWord; 268 while (i-- > 0) _mask[i] = 0; 269 } 270 271 void generate() { 272 iterate(); 273 } 274 }; 275 276 bool OopMapCacheEntry::verify_mask(CellTypeState* vars, CellTypeState* stack, int max_locals, int stack_top) { 277 // Check mask includes map 278 VerifyClosure blk(this); 279 iterate_oop(&blk); 280 if (blk.failed()) return false; 281 282 // Check if map is generated correctly 283 // (Use ?: operator to make sure all 'true' & 'false' are represented exactly the same so we can use == afterwards) 284 const bool log = log_is_enabled(Trace, interpreter, oopmap); 285 LogStream st(Log(interpreter, oopmap)::trace()); 286 287 if (log) st.print("Locals (%d): ", max_locals); 288 for(int i = 0; i < max_locals; i++) { 289 bool v1 = is_oop(i) ? true : false; 290 bool v2 = vars[i].is_reference() ? true : false; 291 assert(v1 == v2, "locals oop mask generation error"); 292 if (log) st.print("%d", v1 ? 1 : 0); 293 } 294 if (log) st.cr(); 295 296 if (log) st.print("Stack (%d): ", stack_top); 297 for(int j = 0; j < stack_top; j++) { 298 bool v1 = is_oop(max_locals + j) ? true : false; 299 bool v2 = stack[j].is_reference() ? true : false; 300 assert(v1 == v2, "stack oop mask generation error"); 301 if (log) st.print("%d", v1 ? 1 : 0); 302 } 303 if (log) st.cr(); 304 return true; 305 } 306 307 void OopMapCacheEntry::allocate_bit_mask() { 308 if (mask_size() > small_mask_limit) { 309 assert(_bit_mask[0] == 0, "bit mask should be new or just flushed"); 310 _bit_mask[0] = (intptr_t) 311 NEW_C_HEAP_ARRAY(uintptr_t, mask_word_size(), mtClass); 312 } 313 } 314 315 void OopMapCacheEntry::deallocate_bit_mask() { 316 if (mask_size() > small_mask_limit && _bit_mask[0] != 0) { 317 assert(!Thread::current()->resource_area()->contains((void*)_bit_mask[0]), 318 "This bit mask should not be in the resource area"); 319 FREE_C_HEAP_ARRAY(uintptr_t, _bit_mask[0]); 320 debug_only(_bit_mask[0] = 0;) 321 } 322 } 323 324 325 void OopMapCacheEntry::fill_for_native(const methodHandle& mh) { 326 assert(mh->is_native(), "method must be native method"); 327 set_mask_size(mh->size_of_parameters() * bits_per_entry); 328 allocate_bit_mask(); 329 // fill mask for parameters 330 MaskFillerForNative mf(mh, bit_mask(), mask_size()); 331 mf.generate(); 332 } 333 334 335 void OopMapCacheEntry::fill(const methodHandle& method, int bci) { 336 // Flush entry to deallocate an existing entry 337 flush(); 338 set_method(method()); 339 set_bci(checked_cast<unsigned short>(bci)); // bci is always u2 340 if (method->is_native()) { 341 // Native method activations have oops only among the parameters and one 342 // extra oop following the parameters (the mirror for static native methods). 343 fill_for_native(method); 344 } else { 345 OopMapForCacheEntry gen(method, bci, this); 346 if (!gen.compute_map(Thread::current())) { 347 fatal("Unrecoverable verification or out-of-memory error"); 348 } 349 } 350 } 351 352 353 void OopMapCacheEntry::set_mask(CellTypeState *vars, CellTypeState *stack, int stack_top) { 354 // compute bit mask size 355 int max_locals = method()->max_locals(); 356 int n_entries = max_locals + stack_top; 357 set_mask_size(n_entries * bits_per_entry); 358 allocate_bit_mask(); 359 set_expression_stack_size(stack_top); 360 361 // compute bits 362 int word_index = 0; 363 uintptr_t value = 0; 364 uintptr_t mask = 1; 365 366 _num_oops = 0; 367 CellTypeState* cell = vars; 368 for (int entry_index = 0; entry_index < n_entries; entry_index++, mask <<= bits_per_entry, cell++) { 369 // store last word 370 if (mask == 0) { 371 bit_mask()[word_index++] = value; 372 value = 0; 373 mask = 1; 374 } 375 376 // switch to stack when done with locals 377 if (entry_index == max_locals) { 378 cell = stack; 379 } 380 381 // set oop bit 382 if ( cell->is_reference()) { 383 value |= (mask << oop_bit_number ); 384 _num_oops++; 385 } 386 387 // set dead bit 388 if (!cell->is_live()) { 389 value |= (mask << dead_bit_number); 390 assert(!cell->is_reference(), "dead value marked as oop"); 391 } 392 } 393 394 // make sure last word is stored 395 bit_mask()[word_index] = value; 396 397 // verify bit mask 398 assert(verify_mask(vars, stack, max_locals, stack_top), "mask could not be verified"); 399 } 400 401 void OopMapCacheEntry::flush() { 402 deallocate_bit_mask(); 403 initialize(); 404 } 405 406 void OopMapCacheEntry::deallocate(OopMapCacheEntry* const entry) { 407 entry->flush(); 408 FREE_C_HEAP_OBJ(entry); 409 } 410 411 // Implementation of OopMapCache 412 413 void InterpreterOopMap::resource_copy(OopMapCacheEntry* from) { 414 assert(_resource_allocate_bit_mask, 415 "Should not resource allocate the _bit_mask"); 416 assert(from->has_valid_mask(), 417 "Cannot copy entry with an invalid mask"); 418 419 set_method(from->method()); 420 set_bci(from->bci()); 421 set_mask_size(from->mask_size()); 422 set_expression_stack_size(from->expression_stack_size()); 423 _num_oops = from->num_oops(); 424 425 // Is the bit mask contained in the entry? 426 if (from->mask_size() <= small_mask_limit) { 427 memcpy((void *)_bit_mask, (void *)from->_bit_mask, 428 mask_word_size() * BytesPerWord); 429 } else { 430 // The expectation is that this InterpreterOopMap is a recently created 431 // and empty. It is used to get a copy of a cached entry. 432 // If the bit mask has a value, it should be in the 433 // resource area. 434 assert(_bit_mask[0] == 0 || 435 Thread::current()->resource_area()->contains((void*)_bit_mask[0]), 436 "The bit mask should have been allocated from a resource area"); 437 // Allocate the bit_mask from a Resource area for performance. Allocating 438 // from the C heap as is done for OopMapCache has a significant 439 // performance impact. 440 _bit_mask[0] = (uintptr_t) NEW_RESOURCE_ARRAY(uintptr_t, mask_word_size()); 441 assert(_bit_mask[0] != 0, "bit mask was not allocated"); 442 memcpy((void*) _bit_mask[0], (void*) from->_bit_mask[0], 443 mask_word_size() * BytesPerWord); 444 } 445 } 446 447 inline unsigned int OopMapCache::hash_value_for(const methodHandle& method, int bci) const { 448 // We use method->code_size() rather than method->identity_hash() below since 449 // the mark may not be present if a pointer to the method is already reversed. 450 return ((unsigned int) bci) 451 ^ ((unsigned int) method->max_locals() << 2) 452 ^ ((unsigned int) method->code_size() << 4) 453 ^ ((unsigned int) method->size_of_parameters() << 6); 454 } 455 456 OopMapCacheEntry* volatile OopMapCache::_old_entries = nullptr; 457 458 OopMapCache::OopMapCache() { 459 _array = NEW_C_HEAP_ARRAY(OopMapCacheEntry*, _size, mtClass); 460 for(int i = 0; i < _size; i++) _array[i] = nullptr; 461 } 462 463 464 OopMapCache::~OopMapCache() { 465 assert(_array != nullptr, "sanity check"); 466 // Deallocate oop maps that are allocated out-of-line 467 flush(); 468 // Deallocate array 469 FREE_C_HEAP_ARRAY(OopMapCacheEntry*, _array); 470 } 471 472 OopMapCacheEntry* OopMapCache::entry_at(int i) const { 473 return Atomic::load_acquire(&(_array[i % _size])); 474 } 475 476 bool OopMapCache::put_at(int i, OopMapCacheEntry* entry, OopMapCacheEntry* old) { 477 return Atomic::cmpxchg(&_array[i % _size], old, entry) == old; 478 } 479 480 void OopMapCache::flush() { 481 for (int i = 0; i < _size; i++) { 482 OopMapCacheEntry* entry = _array[i]; 483 if (entry != nullptr) { 484 _array[i] = nullptr; // no barrier, only called in OopMapCache destructor 485 OopMapCacheEntry::deallocate(entry); 486 } 487 } 488 } 489 490 void OopMapCache::flush_obsolete_entries() { 491 assert(SafepointSynchronize::is_at_safepoint(), "called by RedefineClasses in a safepoint"); 492 for (int i = 0; i < _size; i++) { 493 OopMapCacheEntry* entry = _array[i]; 494 if (entry != nullptr && !entry->is_empty() && entry->method()->is_old()) { 495 // Cache entry is occupied by an old redefined method and we don't want 496 // to pin it down so flush the entry. 497 if (log_is_enabled(Debug, redefine, class, oopmap)) { 498 ResourceMark rm; 499 log_debug(redefine, class, interpreter, oopmap) 500 ("flush: %s(%s): cached entry @%d", 501 entry->method()->name()->as_C_string(), entry->method()->signature()->as_C_string(), i); 502 } 503 _array[i] = nullptr; 504 OopMapCacheEntry::deallocate(entry); 505 } 506 } 507 } 508 509 // Called by GC for thread root scan during a safepoint only. The other interpreted frame oopmaps 510 // are generated locally and not cached. 511 void OopMapCache::lookup(const methodHandle& method, 512 int bci, 513 InterpreterOopMap* entry_for) { 514 assert(SafepointSynchronize::is_at_safepoint(), "called by GC in a safepoint"); 515 int probe = hash_value_for(method, bci); 516 int i; 517 OopMapCacheEntry* entry = nullptr; 518 519 if (log_is_enabled(Debug, interpreter, oopmap)) { 520 static int count = 0; 521 ResourceMark rm; 522 log_debug(interpreter, oopmap) 523 ("%d - Computing oopmap at bci %d for %s at hash %d", ++count, bci, 524 method()->name_and_sig_as_C_string(), probe); 525 } 526 527 // Search hashtable for match 528 for(i = 0; i < _probe_depth; i++) { 529 entry = entry_at(probe + i); 530 if (entry != nullptr && !entry->is_empty() && entry->match(method, bci)) { 531 entry_for->resource_copy(entry); 532 assert(!entry_for->is_empty(), "A non-empty oop map should be returned"); 533 log_debug(interpreter, oopmap)("- found at hash %d", probe + i); 534 return; 535 } 536 } 537 538 // Entry is not in hashtable. 539 // Compute entry 540 541 OopMapCacheEntry* tmp = NEW_C_HEAP_OBJ(OopMapCacheEntry, mtClass); 542 tmp->initialize(); 543 tmp->fill(method, bci); 544 entry_for->resource_copy(tmp); 545 546 if (method->should_not_be_cached()) { 547 // It is either not safe or not a good idea to cache this Method* 548 // at this time. We give the caller of lookup() a copy of the 549 // interesting info via parameter entry_for, but we don't add it to 550 // the cache. See the gory details in Method*.cpp. 551 OopMapCacheEntry::deallocate(tmp); 552 return; 553 } 554 555 // First search for an empty slot 556 for(i = 0; i < _probe_depth; i++) { 557 entry = entry_at(probe + i); 558 if (entry == nullptr) { 559 if (put_at(probe + i, tmp, nullptr)) { 560 assert(!entry_for->is_empty(), "A non-empty oop map should be returned"); 561 return; 562 } 563 } 564 } 565 566 log_debug(interpreter, oopmap)("*** collision in oopmap cache - flushing item ***"); 567 568 // No empty slot (uncommon case). Use (some approximation of a) LRU algorithm 569 // where the first entry in the collision array is replaced with the new one. 570 OopMapCacheEntry* old = entry_at(probe + 0); 571 if (put_at(probe + 0, tmp, old)) { 572 enqueue_for_cleanup(old); 573 } else { 574 OopMapCacheEntry::deallocate(tmp); 575 } 576 577 assert(!entry_for->is_empty(), "A non-empty oop map should be returned"); 578 return; 579 } 580 581 void OopMapCache::enqueue_for_cleanup(OopMapCacheEntry* entry) { 582 bool success = false; 583 OopMapCacheEntry* head; 584 do { 585 head = _old_entries; 586 entry->_next = head; 587 success = Atomic::cmpxchg(&_old_entries, head, entry) == head; 588 } while (!success); 589 590 if (log_is_enabled(Debug, interpreter, oopmap)) { 591 ResourceMark rm; 592 log_debug(interpreter, oopmap)("enqueue %s at bci %d for cleanup", 593 entry->method()->name_and_sig_as_C_string(), entry->bci()); 594 } 595 } 596 597 // This is called after GC threads are done and nothing is accessing the old_entries 598 // list, so no synchronization needed. 599 void OopMapCache::cleanup_old_entries() { 600 OopMapCacheEntry* entry = _old_entries; 601 _old_entries = nullptr; 602 while (entry != nullptr) { 603 if (log_is_enabled(Debug, interpreter, oopmap)) { 604 ResourceMark rm; 605 log_debug(interpreter, oopmap)("cleanup entry %s at bci %d", 606 entry->method()->name_and_sig_as_C_string(), entry->bci()); 607 } 608 OopMapCacheEntry* next = entry->_next; 609 OopMapCacheEntry::deallocate(entry); 610 entry = next; 611 } 612 } 613 614 void OopMapCache::compute_one_oop_map(const methodHandle& method, int bci, InterpreterOopMap* entry) { 615 // Due to the invariants above it's tricky to allocate a temporary OopMapCacheEntry on the stack 616 OopMapCacheEntry* tmp = NEW_C_HEAP_OBJ(OopMapCacheEntry, mtClass); 617 tmp->initialize(); 618 tmp->fill(method, bci); 619 if (tmp->has_valid_mask()) { 620 entry->resource_copy(tmp); 621 } 622 OopMapCacheEntry::deallocate(tmp); 623 }