1 /*
2 * Copyright (c) 1997, 2024, 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 #include "utilities/globalCounter.inline.hpp"
39
40 class OopMapCacheEntry: private InterpreterOopMap {
41 friend class InterpreterOopMap;
42 friend class OopMapForCacheEntry;
43 friend class OopMapCache;
44 friend class VerifyClosure;
45
46 private:
47 OopMapCacheEntry* _next;
48
49 protected:
50 // Initialization
51 void fill(const methodHandle& method, int bci);
52 // fills the bit mask for native calls
53 void fill_for_native(const methodHandle& method);
54 void set_mask(CellTypeState* vars, CellTypeState* stack, int stack_top);
55
56 // Deallocate bit masks and initialize fields
57 void flush();
58
59 static void deallocate(OopMapCacheEntry* const entry);
60
61 private:
62 void allocate_bit_mask(); // allocates the bit mask on C heap f necessary
63 void deallocate_bit_mask(); // allocates the bit mask on C heap f necessary
64 bool verify_mask(CellTypeState *vars, CellTypeState *stack, int max_locals, int stack_top);
65
66 public:
67 OopMapCacheEntry() : InterpreterOopMap() {
68 _next = nullptr;
69 }
70 };
71
72
73 // Implementation of OopMapForCacheEntry
74 // (subclass of GenerateOopMap, initializes an OopMapCacheEntry for a given method and bci)
75
76 class OopMapForCacheEntry: public GenerateOopMap {
77 OopMapCacheEntry *_entry;
78 int _bci;
79 int _stack_top;
80
81 virtual bool report_results() const { return false; }
82 virtual bool possible_gc_point (BytecodeStream *bcs);
83 virtual void fill_stackmap_prolog (int nof_gc_points);
84 virtual void fill_stackmap_epilog ();
85 virtual void fill_stackmap_for_opcodes (BytecodeStream *bcs,
86 CellTypeState* vars,
87 CellTypeState* stack,
88 int stack_top);
89 virtual void fill_init_vars (GrowableArray<intptr_t> *init_vars);
90
91 public:
92 OopMapForCacheEntry(const methodHandle& method, int bci, OopMapCacheEntry *entry);
93
94 // Computes stack map for (method,bci) and initialize entry
95 bool compute_map(Thread* current);
96 int size();
97 };
98
99
100 OopMapForCacheEntry::OopMapForCacheEntry(const methodHandle& method, int bci, OopMapCacheEntry* entry) : GenerateOopMap(method) {
101 _bci = bci;
102 _entry = entry;
103 _stack_top = -1;
104 }
105
106
107 bool OopMapForCacheEntry::compute_map(Thread* current) {
108 assert(!method()->is_native(), "cannot compute oop map for native methods");
109 // First check if it is a method where the stackmap is always empty
110 if (method()->code_size() == 0 || method()->max_locals() + method()->max_stack() == 0) {
111 _entry->set_mask_size(0);
112 } else {
113 ResourceMark rm;
114 if (!GenerateOopMap::compute_map(current)) {
115 fatal("Unrecoverable verification or out-of-memory error");
116 return false;
117 }
118 result_for_basicblock(_bci);
119 }
120 return true;
121 }
122
123
124 bool OopMapForCacheEntry::possible_gc_point(BytecodeStream *bcs) {
125 return false; // We are not reporting any result. We call result_for_basicblock directly
126 }
127
128
129 void OopMapForCacheEntry::fill_stackmap_prolog(int nof_gc_points) {
130 // Do nothing
131 }
132
133
134 void OopMapForCacheEntry::fill_stackmap_epilog() {
135 // Do nothing
136 }
137
138
139 void OopMapForCacheEntry::fill_init_vars(GrowableArray<intptr_t> *init_vars) {
140 // Do nothing
141 }
142
143
144 void OopMapForCacheEntry::fill_stackmap_for_opcodes(BytecodeStream *bcs,
145 CellTypeState* vars,
146 CellTypeState* stack,
147 int stack_top) {
148 // Only interested in one specific bci
149 if (bcs->bci() == _bci) {
150 _entry->set_mask(vars, stack, stack_top);
151 _stack_top = stack_top;
152 }
153 }
154
155
156 int OopMapForCacheEntry::size() {
157 assert(_stack_top != -1, "compute_map must be called first");
158 return ((method()->is_static()) ? 0 : 1) + method()->max_locals() + _stack_top;
159 }
160
161
162 // Implementation of InterpreterOopMap and OopMapCacheEntry
163
164 class VerifyClosure : public OffsetClosure {
165 private:
166 OopMapCacheEntry* _entry;
167 bool _failed;
168
169 public:
170 VerifyClosure(OopMapCacheEntry* entry) { _entry = entry; _failed = false; }
171 void offset_do(int offset) { if (!_entry->is_oop(offset)) _failed = true; }
172 bool failed() const { return _failed; }
173 };
174
175 InterpreterOopMap::InterpreterOopMap() {
176 initialize();
177 }
178
179 InterpreterOopMap::~InterpreterOopMap() {
180 if (has_valid_mask() && mask_size() > small_mask_limit) {
181 assert(_bit_mask[0] != 0, "should have pointer to C heap");
182 FREE_C_HEAP_ARRAY(uintptr_t, _bit_mask[0]);
183 }
184 }
185
186 bool InterpreterOopMap::is_empty() const {
187 bool result = _method == nullptr;
188 assert(_method != nullptr || (_bci == 0 &&
189 (_mask_size == 0 || _mask_size == USHRT_MAX) &&
190 _bit_mask[0] == 0), "Should be completely empty");
191 return result;
192 }
193
194 void InterpreterOopMap::initialize() {
195 _method = nullptr;
196 _mask_size = USHRT_MAX; // This value should cause a failure quickly
197 _bci = 0;
198 _expression_stack_size = 0;
199 _num_oops = 0;
200 for (int i = 0; i < N; i++) _bit_mask[i] = 0;
201 }
202
203 void InterpreterOopMap::iterate_oop(OffsetClosure* oop_closure) const {
204 int n = number_of_entries();
205 int word_index = 0;
206 uintptr_t value = 0;
207 uintptr_t mask = 0;
208 // iterate over entries
209 for (int i = 0; i < n; i++, mask <<= bits_per_entry) {
210 // get current word
211 if (mask == 0) {
212 value = bit_mask()[word_index++];
213 mask = 1;
214 }
215 // test for oop
216 if ((value & (mask << oop_bit_number)) != 0) oop_closure->offset_do(i);
217 }
218 }
219
220 void InterpreterOopMap::print() const {
221 int n = number_of_entries();
222 tty->print("oop map for ");
223 method()->print_value();
224 tty->print(" @ %d = [%d] { ", bci(), n);
225 for (int i = 0; i < n; i++) {
226 if (is_dead(i)) tty->print("%d+ ", i);
227 else
228 if (is_oop(i)) tty->print("%d ", i);
229 }
230 tty->print_cr("}");
231 }
232
233 class MaskFillerForNative: public NativeSignatureIterator {
234 private:
235 uintptr_t * _mask; // the bit mask to be filled
236 int _size; // the mask size in bits
237
238 void set_one(int i) {
239 i *= InterpreterOopMap::bits_per_entry;
240 assert(0 <= i && i < _size, "offset out of bounds");
241 _mask[i / BitsPerWord] |= (((uintptr_t) 1 << InterpreterOopMap::oop_bit_number) << (i % BitsPerWord));
242 }
243
244 public:
245 void pass_byte() { /* ignore */ }
246 void pass_short() { /* ignore */ }
247 void pass_int() { /* ignore */ }
248 void pass_long() { /* ignore */ }
249 void pass_float() { /* ignore */ }
250 void pass_double() { /* ignore */ }
251 void pass_object() { set_one(offset()); }
252
253 MaskFillerForNative(const methodHandle& method, uintptr_t* mask, int size) : NativeSignatureIterator(method) {
254 _mask = mask;
255 _size = size;
256 // initialize with 0
257 int i = (size + BitsPerWord - 1) / BitsPerWord;
258 while (i-- > 0) _mask[i] = 0;
259 }
260
261 void generate() {
262 iterate();
263 }
264 };
265
266 bool OopMapCacheEntry::verify_mask(CellTypeState* vars, CellTypeState* stack, int max_locals, int stack_top) {
267 // Check mask includes map
268 VerifyClosure blk(this);
269 iterate_oop(&blk);
270 if (blk.failed()) return false;
271
272 // Check if map is generated correctly
273 // (Use ?: operator to make sure all 'true' & 'false' are represented exactly the same so we can use == afterwards)
274 const bool log = log_is_enabled(Trace, interpreter, oopmap);
275 LogStream st(Log(interpreter, oopmap)::trace());
276
277 if (log) st.print("Locals (%d): ", max_locals);
278 for(int i = 0; i < max_locals; i++) {
279 bool v1 = is_oop(i) ? true : false;
280 bool v2 = vars[i].is_reference();
281 assert(v1 == v2, "locals oop mask generation error");
282 if (log) st.print("%d", v1 ? 1 : 0);
283 }
284 if (log) st.cr();
285
286 if (log) st.print("Stack (%d): ", stack_top);
287 for(int j = 0; j < stack_top; j++) {
288 bool v1 = is_oop(max_locals + j) ? true : false;
289 bool v2 = stack[j].is_reference();
290 assert(v1 == v2, "stack oop mask generation error");
291 if (log) st.print("%d", v1 ? 1 : 0);
292 }
293 if (log) st.cr();
294 return true;
295 }
296
297 void OopMapCacheEntry::allocate_bit_mask() {
298 if (mask_size() > small_mask_limit) {
299 assert(_bit_mask[0] == 0, "bit mask should be new or just flushed");
300 _bit_mask[0] = (intptr_t)
301 NEW_C_HEAP_ARRAY(uintptr_t, mask_word_size(), mtClass);
302 }
303 }
304
305 void OopMapCacheEntry::deallocate_bit_mask() {
306 if (mask_size() > small_mask_limit && _bit_mask[0] != 0) {
307 assert(!Thread::current()->resource_area()->contains((void*)_bit_mask[0]),
308 "This bit mask should not be in the resource area");
309 FREE_C_HEAP_ARRAY(uintptr_t, _bit_mask[0]);
310 debug_only(_bit_mask[0] = 0;)
311 }
312 }
313
314
315 void OopMapCacheEntry::fill_for_native(const methodHandle& mh) {
316 assert(mh->is_native(), "method must be native method");
317 set_mask_size(mh->size_of_parameters() * bits_per_entry);
318 allocate_bit_mask();
319 // fill mask for parameters
320 MaskFillerForNative mf(mh, bit_mask(), mask_size());
321 mf.generate();
322 }
323
324
325 void OopMapCacheEntry::fill(const methodHandle& method, int bci) {
326 // Flush entry to deallocate an existing entry
327 flush();
328 set_method(method());
329 set_bci(checked_cast<unsigned short>(bci)); // bci is always u2
330 if (method->is_native()) {
331 // Native method activations have oops only among the parameters and one
332 // extra oop following the parameters (the mirror for static native methods).
333 fill_for_native(method);
334 } else {
335 OopMapForCacheEntry gen(method, bci, this);
336 if (!gen.compute_map(Thread::current())) {
337 fatal("Unrecoverable verification or out-of-memory error");
338 }
339 }
340 }
341
342
343 void OopMapCacheEntry::set_mask(CellTypeState *vars, CellTypeState *stack, int stack_top) {
344 // compute bit mask size
345 int max_locals = method()->max_locals();
346 int n_entries = max_locals + stack_top;
347 set_mask_size(n_entries * bits_per_entry);
348 allocate_bit_mask();
349 set_expression_stack_size(stack_top);
350
351 // compute bits
352 int word_index = 0;
353 uintptr_t value = 0;
354 uintptr_t mask = 1;
355
356 _num_oops = 0;
357 CellTypeState* cell = vars;
358 for (int entry_index = 0; entry_index < n_entries; entry_index++, mask <<= bits_per_entry, cell++) {
359 // store last word
360 if (mask == 0) {
361 bit_mask()[word_index++] = value;
362 value = 0;
363 mask = 1;
364 }
365
366 // switch to stack when done with locals
367 if (entry_index == max_locals) {
368 cell = stack;
369 }
370
371 // set oop bit
372 if (cell->is_reference()) {
373 value |= (mask << oop_bit_number );
374 _num_oops++;
375 }
376
377 // set dead bit
378 if (!cell->is_live()) {
379 value |= (mask << dead_bit_number);
380 assert(!cell->is_reference(), "dead value marked as oop");
381 }
382 }
383
384 // make sure last word is stored
385 bit_mask()[word_index] = value;
386
387 // verify bit mask
388 assert(verify_mask(vars, stack, max_locals, stack_top), "mask could not be verified");
389 }
390
391 void OopMapCacheEntry::flush() {
392 deallocate_bit_mask();
393 initialize();
394 }
395
396 void OopMapCacheEntry::deallocate(OopMapCacheEntry* const entry) {
397 entry->flush();
398 FREE_C_HEAP_OBJ(entry);
399 }
400
401 // Implementation of OopMapCache
402
403 void InterpreterOopMap::copy_from(const OopMapCacheEntry* src) {
404 // The expectation is that this InterpreterOopMap is recently created
405 // and empty. It is used to get a copy of a cached entry.
406 assert(!has_valid_mask(), "InterpreterOopMap object can only be filled once");
407 assert(src->has_valid_mask(), "Cannot copy entry with an invalid mask");
408
409 set_method(src->method());
410 set_bci(src->bci());
411 set_mask_size(src->mask_size());
412 set_expression_stack_size(src->expression_stack_size());
413 _num_oops = src->num_oops();
414
415 // Is the bit mask contained in the entry?
416 if (src->mask_size() <= small_mask_limit) {
417 memcpy(_bit_mask, src->_bit_mask, mask_word_size() * BytesPerWord);
418 } else {
419 _bit_mask[0] = (uintptr_t) NEW_C_HEAP_ARRAY(uintptr_t, mask_word_size(), mtClass);
420 memcpy((void*) _bit_mask[0], (void*) src->_bit_mask[0], mask_word_size() * BytesPerWord);
421 }
422 }
423
424 inline unsigned int OopMapCache::hash_value_for(const methodHandle& method, int bci) const {
425 // We use method->code_size() rather than method->identity_hash() below since
426 // the mark may not be present if a pointer to the method is already reversed.
427 return ((unsigned int) bci)
428 ^ ((unsigned int) method->max_locals() << 2)
429 ^ ((unsigned int) method->code_size() << 4)
430 ^ ((unsigned int) method->size_of_parameters() << 6);
431 }
432
433 OopMapCacheEntry* volatile OopMapCache::_old_entries = nullptr;
434
435 OopMapCache::OopMapCache() {
436 for(int i = 0; i < size; i++) _array[i] = nullptr;
437 }
438
439
440 OopMapCache::~OopMapCache() {
441 // Deallocate oop maps that are allocated out-of-line
442 flush();
443 }
444
445 OopMapCacheEntry* OopMapCache::entry_at(int i) const {
446 return Atomic::load_acquire(&(_array[i % size]));
447 }
448
449 bool OopMapCache::put_at(int i, OopMapCacheEntry* entry, OopMapCacheEntry* old) {
450 return Atomic::cmpxchg(&_array[i % size], old, entry) == old;
451 }
452
453 void OopMapCache::flush() {
454 for (int i = 0; i < size; i++) {
455 OopMapCacheEntry* entry = _array[i];
456 if (entry != nullptr) {
457 _array[i] = nullptr; // no barrier, only called in OopMapCache destructor
458 OopMapCacheEntry::deallocate(entry);
459 }
460 }
461 }
462
463 void OopMapCache::flush_obsolete_entries() {
464 assert(SafepointSynchronize::is_at_safepoint(), "called by RedefineClasses in a safepoint");
465 for (int i = 0; i < size; i++) {
466 OopMapCacheEntry* entry = _array[i];
467 if (entry != nullptr && !entry->is_empty() && entry->method()->is_old()) {
468 // Cache entry is occupied by an old redefined method and we don't want
469 // to pin it down so flush the entry.
470 if (log_is_enabled(Debug, redefine, class, oopmap)) {
471 ResourceMark rm;
472 log_debug(redefine, class, interpreter, oopmap)
473 ("flush: %s(%s): cached entry @%d",
474 entry->method()->name()->as_C_string(), entry->method()->signature()->as_C_string(), i);
475 }
476 _array[i] = nullptr;
477 OopMapCacheEntry::deallocate(entry);
478 }
479 }
480 }
481
482 // Lookup or compute/cache the entry.
483 void OopMapCache::lookup(const methodHandle& method,
484 int bci,
485 InterpreterOopMap* entry_for) {
486 int probe = hash_value_for(method, bci);
487
488 if (log_is_enabled(Debug, interpreter, oopmap)) {
489 static int count = 0;
490 ResourceMark rm;
491 log_debug(interpreter, oopmap)
492 ("%d - Computing oopmap at bci %d for %s at hash %d", ++count, bci,
493 method()->name_and_sig_as_C_string(), probe);
494 }
495
496 // Search hashtable for match.
497 // Need a critical section to avoid race against concurrent reclamation.
498 {
499 GlobalCounter::CriticalSection cs(Thread::current());
500 for (int i = 0; i < probe_depth; i++) {
501 OopMapCacheEntry *entry = entry_at(probe + i);
502 if (entry != nullptr && !entry->is_empty() && entry->match(method, bci)) {
503 entry_for->copy_from(entry);
504 assert(!entry_for->is_empty(), "A non-empty oop map should be returned");
505 log_debug(interpreter, oopmap)("- found at hash %d", probe + i);
506 return;
507 }
508 }
509 }
510
511 // Entry is not in hashtable.
512 // Compute entry
513
514 OopMapCacheEntry* tmp = NEW_C_HEAP_OBJ(OopMapCacheEntry, mtClass);
515 tmp->initialize();
516 tmp->fill(method, bci);
517 entry_for->copy_from(tmp);
518
519 if (method->should_not_be_cached()) {
520 // It is either not safe or not a good idea to cache this Method*
521 // at this time. We give the caller of lookup() a copy of the
522 // interesting info via parameter entry_for, but we don't add it to
523 // the cache. See the gory details in Method*.cpp.
524 OopMapCacheEntry::deallocate(tmp);
525 return;
526 }
527
528 // First search for an empty slot
529 for (int i = 0; i < probe_depth; i++) {
530 OopMapCacheEntry* entry = entry_at(probe + i);
531 if (entry == nullptr) {
532 if (put_at(probe + i, tmp, nullptr)) {
533 assert(!entry_for->is_empty(), "A non-empty oop map should be returned");
534 return;
535 }
536 }
537 }
538
539 log_debug(interpreter, oopmap)("*** collision in oopmap cache - flushing item ***");
540
541 // No empty slot (uncommon case). Use (some approximation of a) LRU algorithm
542 // where the first entry in the collision array is replaced with the new one.
543 OopMapCacheEntry* old = entry_at(probe + 0);
544 if (put_at(probe + 0, tmp, old)) {
545 // Cannot deallocate old entry on the spot: it can still be used by readers
546 // that got a reference to it before we were able to replace it in the map.
547 // Instead of synchronizing on GlobalCounter here and incurring heavy thread
548 // walk, we do this clean up out of band.
549 enqueue_for_cleanup(old);
550 } else {
551 OopMapCacheEntry::deallocate(tmp);
552 }
553
554 assert(!entry_for->is_empty(), "A non-empty oop map should be returned");
555 return;
556 }
557
558 void OopMapCache::enqueue_for_cleanup(OopMapCacheEntry* entry) {
559 while (true) {
560 OopMapCacheEntry* head = Atomic::load(&_old_entries);
561 entry->_next = head;
562 if (Atomic::cmpxchg(&_old_entries, head, entry) == head) {
563 // Enqueued successfully.
564 break;
565 }
566 }
567
568 if (log_is_enabled(Debug, interpreter, oopmap)) {
569 ResourceMark rm;
570 log_debug(interpreter, oopmap)("enqueue %s at bci %d for cleanup",
571 entry->method()->name_and_sig_as_C_string(), entry->bci());
572 }
573 }
574
575 bool OopMapCache::has_cleanup_work() {
576 return Atomic::load(&_old_entries) != nullptr;
577 }
578
579 void OopMapCache::try_trigger_cleanup() {
580 // See we can take the lock for the notification without blocking.
581 // This allows triggering the cleanup from GC paths, that can hold
582 // the service lock for e.g. oop iteration in service thread.
583 if (has_cleanup_work() && Service_lock->try_lock_without_rank_check()) {
584 Service_lock->notify_all();
585 Service_lock->unlock();
586 }
587 }
588
589 void OopMapCache::cleanup() {
590 OopMapCacheEntry* entry = Atomic::xchg(&_old_entries, (OopMapCacheEntry*)nullptr);
591 if (entry == nullptr) {
592 // No work.
593 return;
594 }
595
596 // About to delete the entries than might still be accessed by other threads
597 // on lookup path. Need to sync up with them before proceeding.
598 GlobalCounter::write_synchronize();
599
600 while (entry != nullptr) {
601 if (log_is_enabled(Debug, interpreter, oopmap)) {
602 ResourceMark rm;
603 log_debug(interpreter, oopmap)("cleanup entry %s at bci %d",
604 entry->method()->name_and_sig_as_C_string(), entry->bci());
605 }
606 OopMapCacheEntry* next = entry->_next;
607 OopMapCacheEntry::deallocate(entry);
608 entry = next;
609 }
610 }
611
612 void OopMapCache::compute_one_oop_map(const methodHandle& method, int bci, InterpreterOopMap* entry) {
613 // Due to the invariants above it's tricky to allocate a temporary OopMapCacheEntry on the stack
614 OopMapCacheEntry* tmp = NEW_C_HEAP_OBJ(OopMapCacheEntry, mtClass);
615 tmp->initialize();
616 tmp->fill(method, bci);
617 if (tmp->has_valid_mask()) {
618 entry->copy_from(tmp);
619 }
620 OopMapCacheEntry::deallocate(tmp);
621 }