1 /*
2 * Copyright (c) 1997, 2021, 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 expection 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 for (int i = 0; i < N; i++) _bit_mask[i] = 0;
206 }
207
208 void InterpreterOopMap::iterate_oop(OffsetClosure* oop_closure) const {
209 int n = number_of_entries();
210 int word_index = 0;
211 uintptr_t value = 0;
212 uintptr_t mask = 0;
213 // iterate over entries
214 for (int i = 0; i < n; i++, mask <<= bits_per_entry) {
215 // get current word
216 if (mask == 0) {
217 value = bit_mask()[word_index++];
218 mask = 1;
219 }
220 // test for oop
221 if ((value & (mask << oop_bit_number)) != 0) oop_closure->offset_do(i);
222 }
223 }
224
225 void InterpreterOopMap::print() const {
226 int n = number_of_entries();
227 tty->print("oop map for ");
228 method()->print_value();
229 tty->print(" @ %d = [%d] { ", bci(), n);
230 for (int i = 0; i < n; i++) {
231 if (is_dead(i)) tty->print("%d+ ", i);
232 else
233 if (is_oop(i)) tty->print("%d ", i);
234 }
235 tty->print_cr("}");
236 }
237
238 class MaskFillerForNative: public NativeSignatureIterator {
239 private:
240 uintptr_t * _mask; // the bit mask to be filled
241 int _size; // the mask size in bits
242
243 void set_one(int i) {
244 i *= InterpreterOopMap::bits_per_entry;
245 assert(0 <= i && i < _size, "offset out of bounds");
246 _mask[i / BitsPerWord] |= (((uintptr_t) 1 << InterpreterOopMap::oop_bit_number) << (i % BitsPerWord));
247 }
248
249 public:
250 void pass_byte() { /* ignore */ }
251 void pass_short() { /* ignore */ }
252 void pass_int() { /* ignore */ }
253 void pass_long() { /* ignore */ }
254 void pass_float() { /* ignore */ }
255 void pass_double() { /* ignore */ }
256 void pass_object() { set_one(offset()); }
257
258 MaskFillerForNative(const methodHandle& method, uintptr_t* mask, int size) : NativeSignatureIterator(method) {
259 _mask = mask;
260 _size = size;
261 // initialize with 0
262 int i = (size + BitsPerWord - 1) / BitsPerWord;
263 while (i-- > 0) _mask[i] = 0;
264 }
265
266 void generate() {
267 iterate();
268 }
269 };
270
271 bool OopMapCacheEntry::verify_mask(CellTypeState* vars, CellTypeState* stack, int max_locals, int stack_top) {
272 // Check mask includes map
273 VerifyClosure blk(this);
274 iterate_oop(&blk);
275 if (blk.failed()) return false;
276
277 // Check if map is generated correctly
278 // (Use ?: operator to make sure all 'true' & 'false' are represented exactly the same so we can use == afterwards)
279 Log(interpreter, oopmap) logv;
280 LogStream st(logv.trace());
281
282 st.print("Locals (%d): ", max_locals);
283 for(int i = 0; i < max_locals; i++) {
284 bool v1 = is_oop(i) ? true : false;
285 bool v2 = vars[i].is_reference();
286 assert(v1 == v2, "locals oop mask generation error");
287 st.print("%d", v1 ? 1 : 0);
288 }
289 st.cr();
290
291 st.print("Stack (%d): ", stack_top);
292 for(int j = 0; j < stack_top; j++) {
293 bool v1 = is_oop(max_locals + j) ? true : false;
294 bool v2 = stack[j].is_reference();
295 assert(v1 == v2, "stack oop mask generation error");
296 st.print("%d", v1 ? 1 : 0);
297 }
298 st.cr();
299 return true;
300 }
301
302 void OopMapCacheEntry::allocate_bit_mask() {
303 if (mask_size() > small_mask_limit) {
304 assert(_bit_mask[0] == 0, "bit mask should be new or just flushed");
305 _bit_mask[0] = (intptr_t)
306 NEW_C_HEAP_ARRAY(uintptr_t, mask_word_size(), mtClass);
307 }
308 }
309
310 void OopMapCacheEntry::deallocate_bit_mask() {
311 if (mask_size() > small_mask_limit && _bit_mask[0] != 0) {
312 assert(!Thread::current()->resource_area()->contains((void*)_bit_mask[0]),
313 "This bit mask should not be in the resource area");
314 FREE_C_HEAP_ARRAY(uintptr_t, _bit_mask[0]);
315 debug_only(_bit_mask[0] = 0;)
316 }
317 }
318
319
320 void OopMapCacheEntry::fill_for_native(const methodHandle& mh) {
321 assert(mh->is_native(), "method must be native method");
322 set_mask_size(mh->size_of_parameters() * bits_per_entry);
323 allocate_bit_mask();
324 // fill mask for parameters
325 MaskFillerForNative mf(mh, bit_mask(), mask_size());
326 mf.generate();
327 }
328
329
330 void OopMapCacheEntry::fill(const methodHandle& method, int bci) {
331 // Flush entry to deallocate an existing entry
332 flush();
333 set_method(method());
334 set_bci(bci);
335 if (method->is_native()) {
336 // Native method activations have oops only among the parameters and one
337 // extra oop following the parameters (the mirror for static native methods).
338 fill_for_native(method);
339 } else {
340 OopMapForCacheEntry gen(method, bci, this);
341 if (!gen.compute_map(Thread::current())) {
342 fatal("Unrecoverable verification or out-of-memory error");
343 }
344 }
345 }
346
347
348 void OopMapCacheEntry::set_mask(CellTypeState *vars, CellTypeState *stack, int stack_top) {
349 // compute bit mask size
350 int max_locals = method()->max_locals();
351 int n_entries = max_locals + stack_top;
352 set_mask_size(n_entries * bits_per_entry);
353 allocate_bit_mask();
354 set_expression_stack_size(stack_top);
355
356 // compute bits
357 int word_index = 0;
358 uintptr_t value = 0;
359 uintptr_t mask = 1;
360
361 CellTypeState* cell = vars;
362 for (int entry_index = 0; entry_index < n_entries; entry_index++, mask <<= bits_per_entry, cell++) {
363 // store last word
364 if (mask == 0) {
365 bit_mask()[word_index++] = value;
366 value = 0;
367 mask = 1;
368 }
369
370 // switch to stack when done with locals
371 if (entry_index == max_locals) {
372 cell = stack;
373 }
374
375 // set oop bit
376 if (cell->is_reference()) {
377 value |= (mask << oop_bit_number );
378 }
379
380 // set dead bit
381 if (!cell->is_live()) {
382 value |= (mask << dead_bit_number);
383 assert(!cell->is_reference(), "dead value marked as oop");
384 }
385 }
386
387 // make sure last word is stored
388 bit_mask()[word_index] = value;
389
390 // verify bit mask
391 assert(verify_mask(vars, stack, max_locals, stack_top), "mask could not be verified");
392 }
393
394 void OopMapCacheEntry::flush() {
395 deallocate_bit_mask();
396 initialize();
397 }
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
406 set_method(from->method());
407 set_bci(from->bci());
408 set_mask_size(from->mask_size());
409 set_expression_stack_size(from->expression_stack_size());
410
411 // Is the bit mask contained in the entry?
412 if (from->mask_size() <= small_mask_limit) {
413 memcpy((void *)_bit_mask, (void *)from->_bit_mask,
414 mask_word_size() * BytesPerWord);
415 } else {
416 // The expectation is that this InterpreterOopMap is a recently created
417 // and empty. It is used to get a copy of a cached entry.
418 // If the bit mask has a value, it should be in the
419 // resource area.
420 assert(_bit_mask[0] == 0 ||
421 Thread::current()->resource_area()->contains((void*)_bit_mask[0]),
422 "The bit mask should have been allocated from a resource area");
423 // Allocate the bit_mask from a Resource area for performance. Allocating
424 // from the C heap as is done for OopMapCache has a significant
425 // performance impact.
426 _bit_mask[0] = (uintptr_t) NEW_RESOURCE_ARRAY(uintptr_t, mask_word_size());
427 assert(_bit_mask[0] != 0, "bit mask was not allocated");
428 memcpy((void*) _bit_mask[0], (void*) from->_bit_mask[0],
429 mask_word_size() * BytesPerWord);
430 }
431 }
432
433 inline unsigned int OopMapCache::hash_value_for(const methodHandle& method, int bci) const {
434 // We use method->code_size() rather than method->identity_hash() below since
435 // the mark may not be present if a pointer to the method is already reversed.
436 return ((unsigned int) bci)
437 ^ ((unsigned int) method->max_locals() << 2)
438 ^ ((unsigned int) method->code_size() << 4)
439 ^ ((unsigned int) method->size_of_parameters() << 6);
440 }
441
442 OopMapCacheEntry* volatile OopMapCache::_old_entries = NULL;
443
444 OopMapCache::OopMapCache() {
445 _array = NEW_C_HEAP_ARRAY(OopMapCacheEntry*, _size, mtClass);
446 for(int i = 0; i < _size; i++) _array[i] = NULL;
447 }
448
449
450 OopMapCache::~OopMapCache() {
451 assert(_array != NULL, "sanity check");
452 // Deallocate oop maps that are allocated out-of-line
453 flush();
454 // Deallocate array
455 FREE_C_HEAP_ARRAY(OopMapCacheEntry*, _array);
456 }
457
458 OopMapCacheEntry* OopMapCache::entry_at(int i) const {
459 return Atomic::load_acquire(&(_array[i % _size]));
460 }
461
462 bool OopMapCache::put_at(int i, OopMapCacheEntry* entry, OopMapCacheEntry* old) {
463 return Atomic::cmpxchg(&_array[i % _size], old, entry) == old;
464 }
465
466 void OopMapCache::flush() {
467 for (int i = 0; i < _size; i++) {
468 OopMapCacheEntry* entry = _array[i];
469 if (entry != NULL) {
470 _array[i] = NULL; // no barrier, only called in OopMapCache destructor
471 entry->flush();
472 FREE_C_HEAP_OBJ(entry);
473 }
474 }
475 }
476
477 void OopMapCache::flush_obsolete_entries() {
478 assert(SafepointSynchronize::is_at_safepoint(), "called by RedefineClasses in a safepoint");
479 for (int i = 0; i < _size; i++) {
480 OopMapCacheEntry* entry = _array[i];
481 if (entry != NULL && !entry->is_empty() && entry->method()->is_old()) {
482 // Cache entry is occupied by an old redefined method and we don't want
483 // to pin it down so flush the entry.
484 if (log_is_enabled(Debug, redefine, class, oopmap)) {
485 ResourceMark rm;
486 log_debug(redefine, class, interpreter, oopmap)
487 ("flush: %s(%s): cached entry @%d",
488 entry->method()->name()->as_C_string(), entry->method()->signature()->as_C_string(), i);
489 }
490 _array[i] = NULL;
491 entry->flush();
492 FREE_C_HEAP_OBJ(entry);
493 }
494 }
495 }
496
497 // Called by GC for thread root scan during a safepoint only. The other interpreted frame oopmaps
498 // are generated locally and not cached.
499 void OopMapCache::lookup(const methodHandle& method,
500 int bci,
501 InterpreterOopMap* entry_for) {
502 assert(SafepointSynchronize::is_at_safepoint(), "called by GC in a safepoint");
503 int probe = hash_value_for(method, bci);
504 int i;
505 OopMapCacheEntry* entry = NULL;
506
507 if (log_is_enabled(Debug, interpreter, oopmap)) {
508 static int count = 0;
509 ResourceMark rm;
510 log_debug(interpreter, oopmap)
511 ("%d - Computing oopmap at bci %d for %s at hash %d", ++count, bci,
512 method()->name_and_sig_as_C_string(), probe);
513 }
514
515 // Search hashtable for match
516 for(i = 0; i < _probe_depth; i++) {
517 entry = entry_at(probe + i);
518 if (entry != NULL && !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 // Entry is not in hashtable.
527 // Compute entry
528
529 OopMapCacheEntry* tmp = NEW_C_HEAP_OBJ(OopMapCacheEntry, mtClass);
530 tmp->initialize();
531 tmp->fill(method, bci);
532 entry_for->resource_copy(tmp);
533
534 if (method->should_not_be_cached()) {
535 // It is either not safe or not a good idea to cache this Method*
536 // at this time. We give the caller of lookup() a copy of the
537 // interesting info via parameter entry_for, but we don't add it to
538 // the cache. See the gory details in Method*.cpp.
539 FREE_C_HEAP_OBJ(tmp);
540 return;
541 }
542
543 // First search for an empty slot
544 for(i = 0; i < _probe_depth; i++) {
545 entry = entry_at(probe + i);
546 if (entry == NULL) {
547 if (put_at(probe + i, tmp, NULL)) {
548 assert(!entry_for->is_empty(), "A non-empty oop map should be returned");
549 return;
550 }
551 }
552 }
553
554 log_debug(interpreter, oopmap)("*** collision in oopmap cache - flushing item ***");
555
556 // No empty slot (uncommon case). Use (some approximation of a) LRU algorithm
557 // where the first entry in the collision array is replaced with the new one.
558 OopMapCacheEntry* old = entry_at(probe + 0);
559 if (put_at(probe + 0, tmp, old)) {
560 enqueue_for_cleanup(old);
561 } else {
562 enqueue_for_cleanup(tmp);
563 }
564
565 assert(!entry_for->is_empty(), "A non-empty oop map should be returned");
566 return;
567 }
568
569 void OopMapCache::enqueue_for_cleanup(OopMapCacheEntry* entry) {
570 bool success = false;
571 OopMapCacheEntry* head;
572 do {
573 head = _old_entries;
574 entry->_next = head;
575 success = Atomic::cmpxchg(&_old_entries, head, entry) == head;
576 } while (!success);
577
578 if (log_is_enabled(Debug, interpreter, oopmap)) {
579 ResourceMark rm;
580 log_debug(interpreter, oopmap)("enqueue %s at bci %d for cleanup",
581 entry->method()->name_and_sig_as_C_string(), entry->bci());
582 }
583 }
584
585 // This is called after GC threads are done and nothing is accessing the old_entries
586 // list, so no synchronization needed.
587 void OopMapCache::cleanup_old_entries() {
588 OopMapCacheEntry* entry = _old_entries;
589 _old_entries = NULL;
590 while (entry != NULL) {
591 if (log_is_enabled(Debug, interpreter, oopmap)) {
592 ResourceMark rm;
593 log_debug(interpreter, oopmap)("cleanup entry %s at bci %d",
594 entry->method()->name_and_sig_as_C_string(), entry->bci());
595 }
596 OopMapCacheEntry* next = entry->_next;
597 entry->flush();
598 FREE_C_HEAP_OBJ(entry);
599 entry = next;
600 }
601 }
602
603 void OopMapCache::compute_one_oop_map(const methodHandle& method, int bci, InterpreterOopMap* entry) {
604 // Due to the invariants above it's tricky to allocate a temporary OopMapCacheEntry on the stack
605 OopMapCacheEntry* tmp = NEW_C_HEAP_OBJ(OopMapCacheEntry, mtClass);
606 tmp->initialize();
607 tmp->fill(method, bci);
608 entry->resource_copy(tmp);
609 FREE_C_HEAP_OBJ(tmp);
610 }