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 #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 #ifdef ASSERT
70 _resource_allocate_bit_mask = false;
71 #endif
72 }
73 };
74
75
76 // Implementation of OopMapForCacheEntry
77 // (subclass of GenerateOopMap, initializes an OopMapCacheEntry for a given method and bci)
78
79 class OopMapForCacheEntry: public GenerateOopMap {
80 OopMapCacheEntry *_entry;
81 int _bci;
82 int _stack_top;
83
84 virtual bool report_results() const { return false; }
85 virtual bool possible_gc_point (BytecodeStream *bcs);
86 virtual void fill_stackmap_prolog (int nof_gc_points);
87 virtual void fill_stackmap_epilog ();
88 virtual void fill_stackmap_for_opcodes (BytecodeStream *bcs,
89 CellTypeState* vars,
90 CellTypeState* stack,
91 int stack_top);
92 virtual void fill_init_vars (GrowableArray<intptr_t> *init_vars);
93
94 public:
95 OopMapForCacheEntry(const methodHandle& method, int bci, OopMapCacheEntry *entry);
96
97 // Computes stack map for (method,bci) and initialize entry
98 bool compute_map(Thread* current);
99 int size();
100 };
101
102
103 OopMapForCacheEntry::OopMapForCacheEntry(const methodHandle& method, int bci, OopMapCacheEntry* entry) : GenerateOopMap(method) {
104 _bci = bci;
105 _entry = entry;
106 _stack_top = -1;
107 }
108
109
110 bool OopMapForCacheEntry::compute_map(Thread* current) {
111 assert(!method()->is_native(), "cannot compute oop map for native methods");
112 // First check if it is a method where the stackmap is always empty
113 if (method()->code_size() == 0 || method()->max_locals() + method()->max_stack() == 0) {
114 _entry->set_mask_size(0);
115 } else {
116 ResourceMark rm;
117 if (!GenerateOopMap::compute_map(current)) {
118 fatal("Unrecoverable verification or out-of-memory error");
119 return false;
120 }
121 result_for_basicblock(_bci);
122 }
123 return true;
124 }
125
126
127 bool OopMapForCacheEntry::possible_gc_point(BytecodeStream *bcs) {
128 return false; // We are not reporting any result. We call result_for_basicblock directly
129 }
130
131
132 void OopMapForCacheEntry::fill_stackmap_prolog(int nof_gc_points) {
133 // Do nothing
134 }
135
136
137 void OopMapForCacheEntry::fill_stackmap_epilog() {
138 // Do nothing
139 }
140
141
142 void OopMapForCacheEntry::fill_init_vars(GrowableArray<intptr_t> *init_vars) {
143 // Do nothing
144 }
145
146
147 void OopMapForCacheEntry::fill_stackmap_for_opcodes(BytecodeStream *bcs,
148 CellTypeState* vars,
149 CellTypeState* stack,
150 int stack_top) {
151 // Only interested in one specific bci
152 if (bcs->bci() == _bci) {
153 _entry->set_mask(vars, stack, stack_top);
154 _stack_top = stack_top;
155 }
156 }
157
158
159 int OopMapForCacheEntry::size() {
160 assert(_stack_top != -1, "compute_map must be called first");
161 return ((method()->is_static()) ? 0 : 1) + method()->max_locals() + _stack_top;
162 }
163
164
165 // Implementation of InterpreterOopMap and OopMapCacheEntry
166
167 class VerifyClosure : public OffsetClosure {
168 private:
169 OopMapCacheEntry* _entry;
170 bool _failed;
171
172 public:
173 VerifyClosure(OopMapCacheEntry* entry) { _entry = entry; _failed = false; }
174 void offset_do(int offset) { if (!_entry->is_oop(offset)) _failed = true; }
175 bool failed() const { return _failed; }
176 };
177
178 InterpreterOopMap::InterpreterOopMap() {
179 initialize();
180 #ifdef ASSERT
181 _resource_allocate_bit_mask = true;
182 #endif
183 }
184
185 bool InterpreterOopMap::is_empty() const {
186 bool result = _method == nullptr;
187 assert(_method != nullptr || (_bci == 0 &&
188 (_mask_size == 0 || _mask_size == USHRT_MAX) &&
189 _bit_mask[0] == 0), "Should be completely empty");
190 return result;
191 }
192
193 void InterpreterOopMap::initialize() {
194 _method = nullptr;
195 _mask_size = USHRT_MAX; // This value should cause a failure quickly
196 _bci = 0;
197 _expression_stack_size = 0;
198 _num_oops = 0;
199 for (int i = 0; i < N; i++) _bit_mask[i] = 0;
200 }
201
202 void InterpreterOopMap::iterate_oop(OffsetClosure* oop_closure) const {
203 int n = number_of_entries();
204 int word_index = 0;
205 uintptr_t value = 0;
206 uintptr_t mask = 0;
207 // iterate over entries
208 for (int i = 0; i < n; i++, mask <<= bits_per_entry) {
209 // get current word
210 if (mask == 0) {
211 value = bit_mask()[word_index++];
212 mask = 1;
213 }
214 // test for oop
215 if ((value & (mask << oop_bit_number)) != 0) oop_closure->offset_do(i);
216 }
217 }
218
219 void InterpreterOopMap::print() const {
220 int n = number_of_entries();
221 tty->print("oop map for ");
222 method()->print_value();
223 tty->print(" @ %d = [%d] { ", bci(), n);
224 for (int i = 0; i < n; i++) {
225 if (is_dead(i)) tty->print("%d+ ", i);
226 else
227 if (is_oop(i)) tty->print("%d ", i);
228 }
229 tty->print_cr("}");
230 }
231
232 class MaskFillerForNative: public NativeSignatureIterator {
233 private:
234 uintptr_t * _mask; // the bit mask to be filled
235 int _size; // the mask size in bits
236
237 void set_one(int i) {
238 i *= InterpreterOopMap::bits_per_entry;
239 assert(0 <= i && i < _size, "offset out of bounds");
240 _mask[i / BitsPerWord] |= (((uintptr_t) 1 << InterpreterOopMap::oop_bit_number) << (i % BitsPerWord));
241 }
242
243 public:
244 void pass_byte() { /* ignore */ }
245 void pass_short() { /* ignore */ }
246 void pass_int() { /* ignore */ }
247 void pass_long() { /* ignore */ }
248 void pass_float() { /* ignore */ }
249 void pass_double() { /* ignore */ }
250 void pass_object() { set_one(offset()); }
251
252 MaskFillerForNative(const methodHandle& method, uintptr_t* mask, int size) : NativeSignatureIterator(method) {
253 _mask = mask;
254 _size = size;
255 // initialize with 0
256 int i = (size + BitsPerWord - 1) / BitsPerWord;
257 while (i-- > 0) _mask[i] = 0;
258 }
259
260 void generate() {
261 iterate();
262 }
263 };
264
265 bool OopMapCacheEntry::verify_mask(CellTypeState* vars, CellTypeState* stack, int max_locals, int stack_top) {
266 // Check mask includes map
267 VerifyClosure blk(this);
268 iterate_oop(&blk);
269 if (blk.failed()) return false;
270
271 // Check if map is generated correctly
272 // (Use ?: operator to make sure all 'true' & 'false' are represented exactly the same so we can use == afterwards)
273 const bool log = log_is_enabled(Trace, interpreter, oopmap);
274 LogStream st(Log(interpreter, oopmap)::trace());
275
276 if (log) st.print("Locals (%d): ", max_locals);
277 for(int i = 0; i < max_locals; i++) {
278 bool v1 = is_oop(i) ? true : false;
279 bool v2 = vars[i].is_reference() ? true : false;
280 assert(v1 == v2, "locals oop mask generation error");
281 if (log) st.print("%d", v1 ? 1 : 0);
282 }
283 if (log) st.cr();
284
285 if (log) st.print("Stack (%d): ", stack_top);
286 for(int j = 0; j < stack_top; j++) {
287 bool v1 = is_oop(max_locals + j) ? true : false;
288 bool v2 = stack[j].is_reference() ? true : false;
289 assert(v1 == v2, "stack oop mask generation error");
290 if (log) st.print("%d", v1 ? 1 : 0);
291 }
292 if (log) st.cr();
293 return true;
294 }
295
296 void OopMapCacheEntry::allocate_bit_mask() {
297 if (mask_size() > small_mask_limit) {
298 assert(_bit_mask[0] == 0, "bit mask should be new or just flushed");
299 _bit_mask[0] = (intptr_t)
300 NEW_C_HEAP_ARRAY(uintptr_t, mask_word_size(), mtClass);
301 }
302 }
303
304 void OopMapCacheEntry::deallocate_bit_mask() {
305 if (mask_size() > small_mask_limit && _bit_mask[0] != 0) {
306 assert(!Thread::current()->resource_area()->contains((void*)_bit_mask[0]),
307 "This bit mask should not be in the resource area");
308 FREE_C_HEAP_ARRAY(uintptr_t, _bit_mask[0]);
309 debug_only(_bit_mask[0] = 0;)
310 }
311 }
312
313
314 void OopMapCacheEntry::fill_for_native(const methodHandle& mh) {
315 assert(mh->is_native(), "method must be native method");
316 set_mask_size(mh->size_of_parameters() * bits_per_entry);
317 allocate_bit_mask();
318 // fill mask for parameters
319 MaskFillerForNative mf(mh, bit_mask(), mask_size());
320 mf.generate();
321 }
322
323
324 void OopMapCacheEntry::fill(const methodHandle& method, int bci) {
325 // Flush entry to deallocate an existing entry
326 flush();
327 set_method(method());
328 set_bci(checked_cast<unsigned short>(bci)); // bci is always u2
329 if (method->is_native()) {
330 // Native method activations have oops only among the parameters and one
331 // extra oop following the parameters (the mirror for static native methods).
332 fill_for_native(method);
333 } else {
334 OopMapForCacheEntry gen(method, bci, this);
335 if (!gen.compute_map(Thread::current())) {
336 fatal("Unrecoverable verification or out-of-memory error");
337 }
338 }
339 }
340
341
342 void OopMapCacheEntry::set_mask(CellTypeState *vars, CellTypeState *stack, int stack_top) {
343 // compute bit mask size
344 int max_locals = method()->max_locals();
345 int n_entries = max_locals + stack_top;
346 set_mask_size(n_entries * bits_per_entry);
347 allocate_bit_mask();
348 set_expression_stack_size(stack_top);
349
350 // compute bits
351 int word_index = 0;
352 uintptr_t value = 0;
353 uintptr_t mask = 1;
354
355 _num_oops = 0;
356 CellTypeState* cell = vars;
357 for (int entry_index = 0; entry_index < n_entries; entry_index++, mask <<= bits_per_entry, cell++) {
358 // store last word
359 if (mask == 0) {
360 bit_mask()[word_index++] = value;
361 value = 0;
362 mask = 1;
363 }
364
365 // switch to stack when done with locals
366 if (entry_index == max_locals) {
367 cell = stack;
368 }
369
370 // set oop bit
371 if ( cell->is_reference()) {
372 value |= (mask << oop_bit_number );
373 _num_oops++;
374 }
375
376 // set dead bit
377 if (!cell->is_live()) {
378 value |= (mask << dead_bit_number);
379 assert(!cell->is_reference(), "dead value marked as oop");
380 }
381 }
382
383 // make sure last word is stored
384 bit_mask()[word_index] = value;
385
386 // verify bit mask
387 assert(verify_mask(vars, stack, max_locals, stack_top), "mask could not be verified");
388 }
389
390 void OopMapCacheEntry::flush() {
391 deallocate_bit_mask();
392 initialize();
393 }
394
395 void OopMapCacheEntry::deallocate(OopMapCacheEntry* const entry) {
396 entry->flush();
397 FREE_C_HEAP_OBJ(entry);
398 }
399
400 // Implementation of OopMapCache
401
402 void InterpreterOopMap::resource_copy(OopMapCacheEntry* from) {
403 assert(_resource_allocate_bit_mask,
404 "Should not resource allocate the _bit_mask");
405 assert(from->has_valid_mask(),
406 "Cannot copy entry with an invalid mask");
407
408 set_method(from->method());
409 set_bci(from->bci());
410 set_mask_size(from->mask_size());
411 set_expression_stack_size(from->expression_stack_size());
412 _num_oops = from->num_oops();
413
414 // Is the bit mask contained in the entry?
415 if (from->mask_size() <= small_mask_limit) {
416 memcpy((void *)_bit_mask, (void *)from->_bit_mask,
417 mask_word_size() * BytesPerWord);
418 } else {
419 // The expectation is that this InterpreterOopMap is a recently created
420 // and empty. It is used to get a copy of a cached entry.
421 // If the bit mask has a value, it should be in the
422 // resource area.
423 assert(_bit_mask[0] == 0 ||
424 Thread::current()->resource_area()->contains((void*)_bit_mask[0]),
425 "The bit mask should have been allocated from a resource area");
426 // Allocate the bit_mask from a Resource area for performance. Allocating
427 // from the C heap as is done for OopMapCache has a significant
428 // performance impact.
429 _bit_mask[0] = (uintptr_t) NEW_RESOURCE_ARRAY(uintptr_t, mask_word_size());
430 assert(_bit_mask[0] != 0, "bit mask was not allocated");
431 memcpy((void*) _bit_mask[0], (void*) from->_bit_mask[0],
432 mask_word_size() * BytesPerWord);
433 }
434 }
435
436 inline unsigned int OopMapCache::hash_value_for(const methodHandle& method, int bci) const {
437 // We use method->code_size() rather than method->identity_hash() below since
438 // the mark may not be present if a pointer to the method is already reversed.
439 return ((unsigned int) bci)
440 ^ ((unsigned int) method->max_locals() << 2)
441 ^ ((unsigned int) method->code_size() << 4)
442 ^ ((unsigned int) method->size_of_parameters() << 6);
443 }
444
445 OopMapCacheEntry* volatile OopMapCache::_old_entries = nullptr;
446
447 OopMapCache::OopMapCache() {
448 _array = NEW_C_HEAP_ARRAY(OopMapCacheEntry*, _size, mtClass);
449 for(int i = 0; i < _size; i++) _array[i] = nullptr;
450 }
451
452
453 OopMapCache::~OopMapCache() {
454 assert(_array != nullptr, "sanity check");
455 // Deallocate oop maps that are allocated out-of-line
456 flush();
457 // Deallocate array
458 FREE_C_HEAP_ARRAY(OopMapCacheEntry*, _array);
459 }
460
461 OopMapCacheEntry* OopMapCache::entry_at(int i) const {
462 return Atomic::load_acquire(&(_array[i % _size]));
463 }
464
465 bool OopMapCache::put_at(int i, OopMapCacheEntry* entry, OopMapCacheEntry* old) {
466 return Atomic::cmpxchg(&_array[i % _size], old, entry) == old;
467 }
468
469 void OopMapCache::flush() {
470 for (int i = 0; i < _size; i++) {
471 OopMapCacheEntry* entry = _array[i];
472 if (entry != nullptr) {
473 _array[i] = nullptr; // no barrier, only called in OopMapCache destructor
474 OopMapCacheEntry::deallocate(entry);
475 }
476 }
477 }
478
479 void OopMapCache::flush_obsolete_entries() {
480 assert(SafepointSynchronize::is_at_safepoint(), "called by RedefineClasses in a safepoint");
481 for (int i = 0; i < _size; i++) {
482 OopMapCacheEntry* entry = _array[i];
483 if (entry != nullptr && !entry->is_empty() && entry->method()->is_old()) {
484 // Cache entry is occupied by an old redefined method and we don't want
485 // to pin it down so flush the entry.
486 if (log_is_enabled(Debug, redefine, class, oopmap)) {
487 ResourceMark rm;
488 log_debug(redefine, class, interpreter, oopmap)
489 ("flush: %s(%s): cached entry @%d",
490 entry->method()->name()->as_C_string(), entry->method()->signature()->as_C_string(), i);
491 }
492 _array[i] = nullptr;
493 OopMapCacheEntry::deallocate(entry);
494 }
495 }
496 }
497
498 // Lookup or compute/cache the entry.
499 void OopMapCache::lookup(const methodHandle& method,
500 int bci,
501 InterpreterOopMap* entry_for) {
502 int probe = hash_value_for(method, bci);
503
504 if (log_is_enabled(Debug, interpreter, oopmap)) {
505 static int count = 0;
506 ResourceMark rm;
507 log_debug(interpreter, oopmap)
508 ("%d - Computing oopmap at bci %d for %s at hash %d", ++count, bci,
509 method()->name_and_sig_as_C_string(), probe);
510 }
511
512 // Search hashtable for match.
513 // Need a critical section to avoid race against concurrent reclamation.
514 {
515 GlobalCounter::CriticalSection cs(Thread::current());
516 for (int i = 0; i < _probe_depth; i++) {
517 OopMapCacheEntry *entry = entry_at(probe + i);
518 if (entry != nullptr && !entry->is_empty() && entry->match(method, bci)) {
519 entry_for->resource_copy(entry);
520 assert(!entry_for->is_empty(), "A non-empty oop map should be returned");
521 log_debug(interpreter, oopmap)("- found at hash %d", probe + i);
522 return;
523 }
524 }
525 }
526
527 // Entry is not in hashtable.
528 // Compute entry
529
530 OopMapCacheEntry* tmp = NEW_C_HEAP_OBJ(OopMapCacheEntry, mtClass);
531 tmp->initialize();
532 tmp->fill(method, bci);
533 entry_for->resource_copy(tmp);
534
535 if (method->should_not_be_cached()) {
536 // It is either not safe or not a good idea to cache this Method*
537 // at this time. We give the caller of lookup() a copy of the
538 // interesting info via parameter entry_for, but we don't add it to
539 // the cache. See the gory details in Method*.cpp.
540 OopMapCacheEntry::deallocate(tmp);
541 return;
542 }
543
544 // First search for an empty slot
545 for (int i = 0; i < _probe_depth; i++) {
546 OopMapCacheEntry* entry = entry_at(probe + i);
547 if (entry == nullptr) {
548 if (put_at(probe + i, tmp, nullptr)) {
549 assert(!entry_for->is_empty(), "A non-empty oop map should be returned");
550 return;
551 }
552 }
553 }
554
555 log_debug(interpreter, oopmap)("*** collision in oopmap cache - flushing item ***");
556
557 // No empty slot (uncommon case). Use (some approximation of a) LRU algorithm
558 // where the first entry in the collision array is replaced with the new one.
559 OopMapCacheEntry* old = entry_at(probe + 0);
560 if (put_at(probe + 0, tmp, old)) {
561 // Cannot deallocate old entry on the spot: it can still be used by readers
562 // that got a reference to it before we were able to replace it in the map.
563 // Instead of synchronizing on GlobalCounter here and incurring heavy thread
564 // walk, we do this clean up out of band.
565 enqueue_for_cleanup(old);
566 } else {
567 OopMapCacheEntry::deallocate(tmp);
568 }
569
570 assert(!entry_for->is_empty(), "A non-empty oop map should be returned");
571 return;
572 }
573
574 void OopMapCache::enqueue_for_cleanup(OopMapCacheEntry* entry) {
575 while (true) {
576 OopMapCacheEntry* head = Atomic::load(&_old_entries);
577 entry->_next = head;
578 if (Atomic::cmpxchg(&_old_entries, head, entry) == head) {
579 // Enqueued successfully.
580 break;
581 }
582 }
583
584 if (log_is_enabled(Debug, interpreter, oopmap)) {
585 ResourceMark rm;
586 log_debug(interpreter, oopmap)("enqueue %s at bci %d for cleanup",
587 entry->method()->name_and_sig_as_C_string(), entry->bci());
588 }
589 }
590
591 bool OopMapCache::has_cleanup_work() {
592 return Atomic::load(&_old_entries) != nullptr;
593 }
594
595 void OopMapCache::try_trigger_cleanup() {
596 // See we can take the lock for the notification without blocking.
597 // This allows triggering the cleanup from GC paths, that can hold
598 // the service lock for e.g. oop iteration in service thread.
599 if (has_cleanup_work() && Service_lock->try_lock_without_rank_check()) {
600 Service_lock->notify_all();
601 Service_lock->unlock();
602 }
603 }
604
605 void OopMapCache::cleanup() {
606 OopMapCacheEntry* entry = Atomic::xchg(&_old_entries, (OopMapCacheEntry*)nullptr);
607 if (entry == nullptr) {
608 // No work.
609 return;
610 }
611
612 // About to delete the entries than might still be accessed by other threads
613 // on lookup path. Need to sync up with them before proceeding.
614 GlobalCounter::write_synchronize();
615
616 while (entry != nullptr) {
617 if (log_is_enabled(Debug, interpreter, oopmap)) {
618 ResourceMark rm;
619 log_debug(interpreter, oopmap)("cleanup entry %s at bci %d",
620 entry->method()->name_and_sig_as_C_string(), entry->bci());
621 }
622 OopMapCacheEntry* next = entry->_next;
623 OopMapCacheEntry::deallocate(entry);
624 entry = next;
625 }
626 }
627
628 void OopMapCache::compute_one_oop_map(const methodHandle& method, int bci, InterpreterOopMap* entry) {
629 // Due to the invariants above it's tricky to allocate a temporary OopMapCacheEntry on the stack
630 OopMapCacheEntry* tmp = NEW_C_HEAP_OBJ(OopMapCacheEntry, mtClass);
631 tmp->initialize();
632 tmp->fill(method, bci);
633 if (tmp->has_valid_mask()) {
634 entry->resource_copy(tmp);
635 }
636 OopMapCacheEntry::deallocate(tmp);
637 }