1 /*
2 * Copyright (c) 1997, 2022, 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/oopMapCache.hpp"
27 #include "logging/log.hpp"
28 #include "logging/logStream.hpp"
29 #include "memory/allocation.inline.hpp"
30 #include "memory/resourceArea.hpp"
31 #include "oops/oop.inline.hpp"
32 #include "runtime/atomic.hpp"
33 #include "runtime/handles.inline.hpp"
34 #include "runtime/safepoint.hpp"
35 #include "runtime/signature.hpp"
36
37 class OopMapCacheEntry: private InterpreterOopMap {
38 friend class InterpreterOopMap;
39 friend class OopMapForCacheEntry;
40 friend class OopMapCache;
41 friend class VerifyClosure;
42
43 private:
44 OopMapCacheEntry* _next;
45
46 protected:
47 // Initialization
48 void fill(const methodHandle& method, int bci);
49 // fills the bit mask for native calls
50 void fill_for_native(const methodHandle& method);
51 void set_mask(CellTypeState* vars, CellTypeState* stack, int stack_top);
52
53 // Deallocate bit masks and initialize fields
54 void flush();
55
56 private:
57 void allocate_bit_mask(); // allocates the bit mask on C heap f necessary
58 void deallocate_bit_mask(); // allocates the bit mask on C heap f necessary
59 bool verify_mask(CellTypeState *vars, CellTypeState *stack, int max_locals, int stack_top);
60
61 public:
62 OopMapCacheEntry() : InterpreterOopMap() {
63 _next = NULL;
64 #ifdef ASSERT
65 _resource_allocate_bit_mask = false;
66 #endif
67 }
68 };
69
70
71 // Implementation of OopMapForCacheEntry
72 // (subclass of GenerateOopMap, initializes an OopMapCacheEntry for a given method and bci)
73
74 class OopMapForCacheEntry: public GenerateOopMap {
75 OopMapCacheEntry *_entry;
76 int _bci;
77 int _stack_top;
78
79 virtual bool report_results() const { return false; }
80 virtual bool possible_gc_point (BytecodeStream *bcs);
81 virtual void fill_stackmap_prolog (int nof_gc_points);
82 virtual void fill_stackmap_epilog ();
83 virtual void fill_stackmap_for_opcodes (BytecodeStream *bcs,
84 CellTypeState* vars,
85 CellTypeState* stack,
86 int stack_top);
87 virtual void fill_init_vars (GrowableArray<intptr_t> *init_vars);
88
89 public:
90 OopMapForCacheEntry(const methodHandle& method, int bci, OopMapCacheEntry *entry);
91
92 // Computes stack map for (method,bci) and initialize entry
93 bool compute_map(Thread* current);
94 int size();
95 };
96
97
98 OopMapForCacheEntry::OopMapForCacheEntry(const methodHandle& method, int bci, OopMapCacheEntry* entry) : GenerateOopMap(method) {
99 _bci = bci;
100 _entry = entry;
101 _stack_top = -1;
102 }
103
104
105 bool OopMapForCacheEntry::compute_map(Thread* current) {
106 assert(!method()->is_native(), "cannot compute oop map for native methods");
107 // First check if it is a method where the stackmap is always empty
108 if (method()->code_size() == 0 || method()->max_locals() + method()->max_stack() == 0) {
109 _entry->set_mask_size(0);
110 } else {
111 ResourceMark rm;
112 if (!GenerateOopMap::compute_map(current)) {
113 fatal("Unrecoverable verification or out-of-memory error");
114 return false;
115 }
116 result_for_basicblock(_bci);
117 }
118 return true;
119 }
120
121
122 bool OopMapForCacheEntry::possible_gc_point(BytecodeStream *bcs) {
123 return false; // We are not reporting any result. We call result_for_basicblock directly
124 }
125
126
127 void OopMapForCacheEntry::fill_stackmap_prolog(int nof_gc_points) {
128 // Do nothing
129 }
130
131
132 void OopMapForCacheEntry::fill_stackmap_epilog() {
133 // Do nothing
134 }
135
136
137 void OopMapForCacheEntry::fill_init_vars(GrowableArray<intptr_t> *init_vars) {
138 // Do nothing
139 }
140
141
142 void OopMapForCacheEntry::fill_stackmap_for_opcodes(BytecodeStream *bcs,
143 CellTypeState* vars,
144 CellTypeState* stack,
145 int stack_top) {
146 // Only interested in one specific bci
147 if (bcs->bci() == _bci) {
148 _entry->set_mask(vars, stack, stack_top);
149 _stack_top = stack_top;
150 }
151 }
152
153
154 int OopMapForCacheEntry::size() {
155 assert(_stack_top != -1, "compute_map must be called first");
156 return ((method()->is_static()) ? 0 : 1) + method()->max_locals() + _stack_top;
157 }
158
159
160 // Implementation of InterpreterOopMap and OopMapCacheEntry
161
162 class VerifyClosure : public OffsetClosure {
163 private:
164 OopMapCacheEntry* _entry;
165 bool _failed;
166
167 public:
168 VerifyClosure(OopMapCacheEntry* entry) { _entry = entry; _failed = false; }
169 void offset_do(int offset) { if (!_entry->is_oop(offset)) _failed = true; }
170 bool failed() const { return _failed; }
171 };
172
173 InterpreterOopMap::InterpreterOopMap() {
174 initialize();
175 #ifdef ASSERT
176 _resource_allocate_bit_mask = true;
177 #endif
178 }
179
180 InterpreterOopMap::~InterpreterOopMap() {
181 // The expectation is that the bit mask was allocated
182 // last in this resource area. That would make the free of the
183 // bit_mask effective (see how FREE_RESOURCE_ARRAY does a free).
184 // If it was not allocated last, there is not a correctness problem
185 // but the space for the bit_mask is not freed.
186 assert(_resource_allocate_bit_mask, "Trying to free C heap space");
187 if (mask_size() > small_mask_limit) {
188 FREE_RESOURCE_ARRAY(uintptr_t, _bit_mask[0], mask_word_size());
189 }
190 }
191
192 bool InterpreterOopMap::is_empty() const {
193 bool result = _method == NULL;
194 assert(_method != NULL || (_bci == 0 &&
195 (_mask_size == 0 || _mask_size == USHRT_MAX) &&
196 _bit_mask[0] == 0), "Should be completely empty");
197 return result;
198 }
199
200 void InterpreterOopMap::initialize() {
201 _method = NULL;
202 _mask_size = USHRT_MAX; // This value should cause a failure quickly
203 _bci = 0;
204 _expression_stack_size = 0;
205 _num_oops = 0;
206 for (int i = 0; i < N; i++) _bit_mask[i] = 0;
207 }
208
209 void InterpreterOopMap::iterate_oop(OffsetClosure* oop_closure) const {
210 int n = number_of_entries();
211 int word_index = 0;
212 uintptr_t value = 0;
213 uintptr_t mask = 0;
214 // iterate over entries
215 for (int i = 0; i < n; i++, mask <<= bits_per_entry) {
216 // get current word
217 if (mask == 0) {
218 value = bit_mask()[word_index++];
219 mask = 1;
220 }
221 // test for oop
222 if ((value & (mask << oop_bit_number)) != 0) oop_closure->offset_do(i);
223 }
224 }
225
226 void InterpreterOopMap::print() const {
227 int n = number_of_entries();
228 tty->print("oop map for ");
229 method()->print_value();
230 tty->print(" @ %d = [%d] { ", bci(), n);
231 for (int i = 0; i < n; i++) {
232 if (is_dead(i)) tty->print("%d+ ", i);
233 else
234 if (is_oop(i)) tty->print("%d ", i);
235 }
236 tty->print_cr("}");
237 }
238
239 class MaskFillerForNative: public NativeSignatureIterator {
240 private:
241 uintptr_t * _mask; // the bit mask to be filled
242 int _size; // the mask size in bits
243
244 void set_one(int i) {
245 i *= InterpreterOopMap::bits_per_entry;
246 assert(0 <= i && i < _size, "offset out of bounds");
247 _mask[i / BitsPerWord] |= (((uintptr_t) 1 << InterpreterOopMap::oop_bit_number) << (i % BitsPerWord));
248 }
249
250 public:
251 void pass_byte() { /* ignore */ }
252 void pass_short() { /* ignore */ }
253 void pass_int() { /* ignore */ }
254 void pass_long() { /* ignore */ }
255 void pass_float() { /* ignore */ }
256 void pass_double() { /* ignore */ }
257 void pass_object() { set_one(offset()); }
258
259 MaskFillerForNative(const methodHandle& method, uintptr_t* mask, int size) : NativeSignatureIterator(method) {
260 _mask = mask;
261 _size = size;
262 // initialize with 0
263 int i = (size + BitsPerWord - 1) / BitsPerWord;
264 while (i-- > 0) _mask[i] = 0;
265 }
266
267 void generate() {
268 iterate();
269 }
270 };
271
272 bool OopMapCacheEntry::verify_mask(CellTypeState* vars, CellTypeState* stack, int max_locals, int stack_top) {
273 // Check mask includes map
274 VerifyClosure blk(this);
275 iterate_oop(&blk);
276 if (blk.failed()) return false;
277
278 // Check if map is generated correctly
279 // (Use ?: operator to make sure all 'true' & 'false' are represented exactly the same so we can use == afterwards)
280 const bool log = log_is_enabled(Trace, interpreter, oopmap);
281 LogStream st(Log(interpreter, oopmap)::trace());
282
283 if (log) st.print("Locals (%d): ", max_locals);
284 for(int i = 0; i < max_locals; i++) {
285 bool v1 = is_oop(i) ? true : false;
286 bool v2 = vars[i].is_reference();
287 assert(v1 == v2, "locals oop mask generation error");
288 if (log) st.print("%d", v1 ? 1 : 0);
289 }
290 if (log) st.cr();
291
292 if (log) st.print("Stack (%d): ", stack_top);
293 for(int j = 0; j < stack_top; j++) {
294 bool v1 = is_oop(max_locals + j) ? true : false;
295 bool v2 = stack[j].is_reference();
296 assert(v1 == v2, "stack oop mask generation error");
297 if (log) st.print("%d", v1 ? 1 : 0);
298 }
299 if (log) st.cr();
300 return true;
301 }
302
303 void OopMapCacheEntry::allocate_bit_mask() {
304 if (mask_size() > small_mask_limit) {
305 assert(_bit_mask[0] == 0, "bit mask should be new or just flushed");
306 _bit_mask[0] = (intptr_t)
307 NEW_C_HEAP_ARRAY(uintptr_t, mask_word_size(), mtClass);
308 }
309 }
310
311 void OopMapCacheEntry::deallocate_bit_mask() {
312 if (mask_size() > small_mask_limit && _bit_mask[0] != 0) {
313 assert(!Thread::current()->resource_area()->contains((void*)_bit_mask[0]),
314 "This bit mask should not be in the resource area");
315 FREE_C_HEAP_ARRAY(uintptr_t, _bit_mask[0]);
316 debug_only(_bit_mask[0] = 0;)
317 }
318 }
319
320
321 void OopMapCacheEntry::fill_for_native(const methodHandle& mh) {
322 assert(mh->is_native(), "method must be native method");
323 set_mask_size(mh->size_of_parameters() * bits_per_entry);
324 allocate_bit_mask();
325 // fill mask for parameters
326 MaskFillerForNative mf(mh, bit_mask(), mask_size());
327 mf.generate();
328 }
329
330
331 void OopMapCacheEntry::fill(const methodHandle& method, int bci) {
332 // Flush entry to deallocate an existing entry
333 flush();
334 set_method(method());
335 set_bci(bci);
336 if (method->is_native()) {
337 // Native method activations have oops only among the parameters and one
338 // extra oop following the parameters (the mirror for static native methods).
339 fill_for_native(method);
340 } else {
341 OopMapForCacheEntry gen(method, bci, this);
342 if (!gen.compute_map(Thread::current())) {
343 fatal("Unrecoverable verification or out-of-memory error");
344 }
345 }
346 }
347
348
349 void OopMapCacheEntry::set_mask(CellTypeState *vars, CellTypeState *stack, int stack_top) {
350 // compute bit mask size
351 int max_locals = method()->max_locals();
352 int n_entries = max_locals + stack_top;
353 set_mask_size(n_entries * bits_per_entry);
354 allocate_bit_mask();
355 set_expression_stack_size(stack_top);
356
357 // compute bits
358 int word_index = 0;
359 uintptr_t value = 0;
360 uintptr_t mask = 1;
361
362 _num_oops = 0;
363 CellTypeState* cell = vars;
364 for (int entry_index = 0; entry_index < n_entries; entry_index++, mask <<= bits_per_entry, cell++) {
365 // store last word
366 if (mask == 0) {
367 bit_mask()[word_index++] = value;
368 value = 0;
369 mask = 1;
370 }
371
372 // switch to stack when done with locals
373 if (entry_index == max_locals) {
374 cell = stack;
375 }
376
377 // set oop bit
378 if (cell->is_reference()) {
379 value |= (mask << oop_bit_number );
380 _num_oops++;
381 }
382
383 // set dead bit
384 if (!cell->is_live()) {
385 value |= (mask << dead_bit_number);
386 assert(!cell->is_reference(), "dead value marked as oop");
387 }
388 }
389
390 // make sure last word is stored
391 bit_mask()[word_index] = value;
392
393 // verify bit mask
394 assert(verify_mask(vars, stack, max_locals, stack_top), "mask could not be verified");
395 }
396
397 void OopMapCacheEntry::flush() {
398 deallocate_bit_mask();
399 initialize();
400 }
401
402
403 // Implementation of OopMapCache
404
405 void InterpreterOopMap::resource_copy(OopMapCacheEntry* from) {
406 assert(_resource_allocate_bit_mask,
407 "Should not resource allocate the _bit_mask");
408
409 set_method(from->method());
410 set_bci(from->bci());
411 set_mask_size(from->mask_size());
412 set_expression_stack_size(from->expression_stack_size());
413 _num_oops = from->num_oops();
414
415 // Is the bit mask contained in the entry?
416 if (from->mask_size() <= small_mask_limit) {
417 memcpy((void *)_bit_mask, (void *)from->_bit_mask,
418 mask_word_size() * BytesPerWord);
419 } else {
420 // The expectation is that this InterpreterOopMap is a recently created
421 // and empty. It is used to get a copy of a cached entry.
422 // If the bit mask has a value, it should be in the
423 // resource area.
424 assert(_bit_mask[0] == 0 ||
425 Thread::current()->resource_area()->contains((void*)_bit_mask[0]),
426 "The bit mask should have been allocated from a resource area");
427 // Allocate the bit_mask from a Resource area for performance. Allocating
428 // from the C heap as is done for OopMapCache has a significant
429 // performance impact.
430 _bit_mask[0] = (uintptr_t) NEW_RESOURCE_ARRAY(uintptr_t, mask_word_size());
431 assert(_bit_mask[0] != 0, "bit mask was not allocated");
432 memcpy((void*) _bit_mask[0], (void*) from->_bit_mask[0],
433 mask_word_size() * BytesPerWord);
434 }
435 }
436
437 inline unsigned int OopMapCache::hash_value_for(const methodHandle& method, int bci) const {
438 // We use method->code_size() rather than method->identity_hash() below since
439 // the mark may not be present if a pointer to the method is already reversed.
440 return ((unsigned int) bci)
441 ^ ((unsigned int) method->max_locals() << 2)
442 ^ ((unsigned int) method->code_size() << 4)
443 ^ ((unsigned int) method->size_of_parameters() << 6);
444 }
445
446 OopMapCacheEntry* volatile OopMapCache::_old_entries = NULL;
447
448 OopMapCache::OopMapCache() {
449 _array = NEW_C_HEAP_ARRAY(OopMapCacheEntry*, _size, mtClass);
450 for(int i = 0; i < _size; i++) _array[i] = NULL;
451 }
452
453
454 OopMapCache::~OopMapCache() {
455 assert(_array != NULL, "sanity check");
456 // Deallocate oop maps that are allocated out-of-line
457 flush();
458 // Deallocate array
459 FREE_C_HEAP_ARRAY(OopMapCacheEntry*, _array);
460 }
461
462 OopMapCacheEntry* OopMapCache::entry_at(int i) const {
463 return Atomic::load_acquire(&(_array[i % _size]));
464 }
465
466 bool OopMapCache::put_at(int i, OopMapCacheEntry* entry, OopMapCacheEntry* old) {
467 return Atomic::cmpxchg(&_array[i % _size], old, entry) == old;
468 }
469
470 void OopMapCache::flush() {
471 for (int i = 0; i < _size; i++) {
472 OopMapCacheEntry* entry = _array[i];
473 if (entry != NULL) {
474 _array[i] = NULL; // no barrier, only called in OopMapCache destructor
475 entry->flush();
476 FREE_C_HEAP_OBJ(entry);
477 }
478 }
479 }
480
481 void OopMapCache::flush_obsolete_entries() {
482 assert(SafepointSynchronize::is_at_safepoint(), "called by RedefineClasses in a safepoint");
483 for (int i = 0; i < _size; i++) {
484 OopMapCacheEntry* entry = _array[i];
485 if (entry != NULL && !entry->is_empty() && entry->method()->is_old()) {
486 // Cache entry is occupied by an old redefined method and we don't want
487 // to pin it down so flush the entry.
488 if (log_is_enabled(Debug, redefine, class, oopmap)) {
489 ResourceMark rm;
490 log_debug(redefine, class, interpreter, oopmap)
491 ("flush: %s(%s): cached entry @%d",
492 entry->method()->name()->as_C_string(), entry->method()->signature()->as_C_string(), i);
493 }
494 _array[i] = NULL;
495 entry->flush();
496 FREE_C_HEAP_OBJ(entry);
497 }
498 }
499 }
500
501 // Called by GC for thread root scan during a safepoint only. The other interpreted frame oopmaps
502 // are generated locally and not cached.
503 void OopMapCache::lookup(const methodHandle& method,
504 int bci,
505 InterpreterOopMap* entry_for) {
506 assert(SafepointSynchronize::is_at_safepoint(), "called by GC in a safepoint");
507 int probe = hash_value_for(method, bci);
508 int i;
509 OopMapCacheEntry* entry = NULL;
510
511 if (log_is_enabled(Debug, interpreter, oopmap)) {
512 static int count = 0;
513 ResourceMark rm;
514 log_debug(interpreter, oopmap)
515 ("%d - Computing oopmap at bci %d for %s at hash %d", ++count, bci,
516 method()->name_and_sig_as_C_string(), probe);
517 }
518
519 // Search hashtable for match
520 for(i = 0; i < _probe_depth; i++) {
521 entry = entry_at(probe + i);
522 if (entry != NULL && !entry->is_empty() && entry->match(method, bci)) {
523 entry_for->resource_copy(entry);
524 assert(!entry_for->is_empty(), "A non-empty oop map should be returned");
525 log_debug(interpreter, oopmap)("- found at hash %d", probe + i);
526 return;
527 }
528 }
529
530 // Entry is not in hashtable.
531 // Compute entry
532
533 OopMapCacheEntry* tmp = NEW_C_HEAP_OBJ(OopMapCacheEntry, mtClass);
534 tmp->initialize();
535 tmp->fill(method, bci);
536 entry_for->resource_copy(tmp);
537
538 if (method->should_not_be_cached()) {
539 // It is either not safe or not a good idea to cache this Method*
540 // at this time. We give the caller of lookup() a copy of the
541 // interesting info via parameter entry_for, but we don't add it to
542 // the cache. See the gory details in Method*.cpp.
543 FREE_C_HEAP_OBJ(tmp);
544 return;
545 }
546
547 // First search for an empty slot
548 for(i = 0; i < _probe_depth; i++) {
549 entry = entry_at(probe + i);
550 if (entry == NULL) {
551 if (put_at(probe + i, tmp, NULL)) {
552 assert(!entry_for->is_empty(), "A non-empty oop map should be returned");
553 return;
554 }
555 }
556 }
557
558 log_debug(interpreter, oopmap)("*** collision in oopmap cache - flushing item ***");
559
560 // No empty slot (uncommon case). Use (some approximation of a) LRU algorithm
561 // where the first entry in the collision array is replaced with the new one.
562 OopMapCacheEntry* old = entry_at(probe + 0);
563 if (put_at(probe + 0, tmp, old)) {
564 enqueue_for_cleanup(old);
565 } else {
566 enqueue_for_cleanup(tmp);
567 }
568
569 assert(!entry_for->is_empty(), "A non-empty oop map should be returned");
570 return;
571 }
572
573 void OopMapCache::enqueue_for_cleanup(OopMapCacheEntry* entry) {
574 bool success = false;
575 OopMapCacheEntry* head;
576 do {
577 head = _old_entries;
578 entry->_next = head;
579 success = Atomic::cmpxchg(&_old_entries, head, entry) == head;
580 } while (!success);
581
582 if (log_is_enabled(Debug, interpreter, oopmap)) {
583 ResourceMark rm;
584 log_debug(interpreter, oopmap)("enqueue %s at bci %d for cleanup",
585 entry->method()->name_and_sig_as_C_string(), entry->bci());
586 }
587 }
588
589 // This is called after GC threads are done and nothing is accessing the old_entries
590 // list, so no synchronization needed.
591 void OopMapCache::cleanup_old_entries() {
592 OopMapCacheEntry* entry = _old_entries;
593 _old_entries = NULL;
594 while (entry != NULL) {
595 if (log_is_enabled(Debug, interpreter, oopmap)) {
596 ResourceMark rm;
597 log_debug(interpreter, oopmap)("cleanup entry %s at bci %d",
598 entry->method()->name_and_sig_as_C_string(), entry->bci());
599 }
600 OopMapCacheEntry* next = entry->_next;
601 entry->flush();
602 FREE_C_HEAP_OBJ(entry);
603 entry = next;
604 }
605 }
606
607 void OopMapCache::compute_one_oop_map(const methodHandle& method, int bci, InterpreterOopMap* entry) {
608 // Due to the invariants above it's tricky to allocate a temporary OopMapCacheEntry on the stack
609 OopMapCacheEntry* tmp = NEW_C_HEAP_OBJ(OopMapCacheEntry, mtClass);
610 tmp->initialize();
611 tmp->fill(method, bci);
612 entry->resource_copy(tmp);
613 FREE_C_HEAP_OBJ(tmp);
614 }