1 /*
2 * Copyright (c) 1997, 2017, 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/handles.inline.hpp"
33 #include "runtime/signature.hpp"
34
35 class OopMapCacheEntry: private InterpreterOopMap {
36 friend class InterpreterOopMap;
37 friend class OopMapForCacheEntry;
38 friend class OopMapCache;
39 friend class VerifyClosure;
40
41 private:
42 OopMapCacheEntry* _next;
43
44 protected:
45 // Initialization
46 void fill(const methodHandle& method, int bci);
47 // fills the bit mask for native calls
48 void fill_for_native(const methodHandle& method);
49 void set_mask(CellTypeState* vars, CellTypeState* stack, int stack_top);
50
51 // Deallocate bit masks and initialize fields
52 void flush();
53
54 private:
55 void allocate_bit_mask(); // allocates the bit mask on C heap f necessary
56 void deallocate_bit_mask(); // allocates the bit mask on C heap f necessary
57 bool verify_mask(CellTypeState *vars, CellTypeState *stack, int max_locals, int stack_top);
58
59 public:
60 OopMapCacheEntry() : InterpreterOopMap() {
61 _next = NULL;
62 #ifdef ASSERT
63 _resource_allocate_bit_mask = false;
64 #endif
65 }
66 };
67
68
69 // Implementation of OopMapForCacheEntry
70 // (subclass of GenerateOopMap, initializes an OopMapCacheEntry for a given method and bci)
71
72 class OopMapForCacheEntry: public GenerateOopMap {
73 OopMapCacheEntry *_entry;
74 int _bci;
75 int _stack_top;
76
77 virtual bool report_results() const { return false; }
78 virtual bool possible_gc_point (BytecodeStream *bcs);
79 virtual void fill_stackmap_prolog (int nof_gc_points);
80 virtual void fill_stackmap_epilog ();
81 virtual void fill_stackmap_for_opcodes (BytecodeStream *bcs,
82 CellTypeState* vars,
83 CellTypeState* stack,
84 int stack_top);
85 virtual void fill_init_vars (GrowableArray<intptr_t> *init_vars);
86
87 public:
88 OopMapForCacheEntry(const methodHandle& method, int bci, OopMapCacheEntry *entry);
89
90 // Computes stack map for (method,bci) and initialize entry
91 void compute_map(TRAPS);
92 int size();
93 };
94
95
96 OopMapForCacheEntry::OopMapForCacheEntry(const methodHandle& method, int bci, OopMapCacheEntry* entry) : GenerateOopMap(method) {
97 _bci = bci;
98 _entry = entry;
99 _stack_top = -1;
100 }
101
102
103 void OopMapForCacheEntry::compute_map(TRAPS) {
104 assert(!method()->is_native(), "cannot compute oop map for native methods");
105 // First check if it is a method where the stackmap is always empty
106 if (method()->code_size() == 0 || method()->max_locals() + method()->max_stack() == 0) {
107 _entry->set_mask_size(0);
108 } else {
109 ResourceMark rm;
110 GenerateOopMap::compute_map(CATCH);
111 result_for_basicblock(_bci);
112 }
113 }
114
115
116 bool OopMapForCacheEntry::possible_gc_point(BytecodeStream *bcs) {
117 return false; // We are not reporting any result. We call result_for_basicblock directly
118 }
119
120
121 void OopMapForCacheEntry::fill_stackmap_prolog(int nof_gc_points) {
122 // Do nothing
123 }
124
125
126 void OopMapForCacheEntry::fill_stackmap_epilog() {
127 // Do nothing
128 }
129
130
131 void OopMapForCacheEntry::fill_init_vars(GrowableArray<intptr_t> *init_vars) {
132 // Do nothing
133 }
134
135
136 void OopMapForCacheEntry::fill_stackmap_for_opcodes(BytecodeStream *bcs,
137 CellTypeState* vars,
138 CellTypeState* stack,
139 int stack_top) {
140 // Only interested in one specific bci
141 if (bcs->bci() == _bci) {
142 _entry->set_mask(vars, stack, stack_top);
143 _stack_top = stack_top;
144 }
145 }
146
147
148 int OopMapForCacheEntry::size() {
149 assert(_stack_top != -1, "compute_map must be called first");
150 return ((method()->is_static()) ? 0 : 1) + method()->max_locals() + _stack_top;
151 }
152
153
154 // Implementation of InterpreterOopMap and OopMapCacheEntry
155
156 class VerifyClosure : public OffsetClosure {
157 private:
158 OopMapCacheEntry* _entry;
159 bool _failed;
160
161 public:
162 VerifyClosure(OopMapCacheEntry* entry) { _entry = entry; _failed = false; }
163 void offset_do(int offset) { if (!_entry->is_oop(offset)) _failed = true; }
164 bool failed() const { return _failed; }
165 };
166
167 InterpreterOopMap::InterpreterOopMap() {
168 initialize();
169 #ifdef ASSERT
170 _resource_allocate_bit_mask = true;
171 #endif
172 }
173
174 InterpreterOopMap::~InterpreterOopMap() {
175 // The expection is that the bit mask was allocated
176 // last in this resource area. That would make the free of the
177 // bit_mask effective (see how FREE_RESOURCE_ARRAY does a free).
178 // If it was not allocated last, there is not a correctness problem
179 // but the space for the bit_mask is not freed.
180 assert(_resource_allocate_bit_mask, "Trying to free C heap space");
181 if (mask_size() > small_mask_limit) {
182 FREE_RESOURCE_ARRAY(uintptr_t, _bit_mask[0], mask_word_size());
183 }
184 }
185
186 bool InterpreterOopMap::is_empty() const {
187 bool result = _method == NULL;
188 assert(_method != NULL || (_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 = NULL;
196 _mask_size = USHRT_MAX; // This value should cause a failure quickly
197 _bci = 0;
198 _expression_stack_size = 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_int() { /* ignore */ }
245 void pass_long() { /* ignore */ }
246 void pass_float() { /* ignore */ }
247 void pass_double() { /* ignore */ }
248 void pass_object() { set_one(offset()); }
249 void pass_valuetype() { set_one(offset()); }
250
251 MaskFillerForNative(const methodHandle& method, uintptr_t* mask, int size) : NativeSignatureIterator(method) {
252 _mask = mask;
253 _size = size;
254 // initialize with 0
255 int i = (size + BitsPerWord - 1) / BitsPerWord;
256 while (i-- > 0) _mask[i] = 0;
257 }
258
259 void generate() {
260 NativeSignatureIterator::iterate();
261 }
262 };
263
264 bool OopMapCacheEntry::verify_mask(CellTypeState* vars, CellTypeState* stack, int max_locals, int stack_top) {
265 // Check mask includes map
266 VerifyClosure blk(this);
267 iterate_oop(&blk);
268 if (blk.failed()) return false;
269
270 // Check if map is generated correctly
271 // (Use ?: operator to make sure all 'true' & 'false' are represented exactly the same so we can use == afterwards)
272 Log(interpreter, oopmap) logv;
273 LogStream st(logv.trace());
274
275 st.print("Locals (%d): ", max_locals);
276 for(int i = 0; i < max_locals; i++) {
277 bool v1 = is_oop(i) ? true : false;
278 bool v2 = vars[i].is_reference();
279 assert(v1 == v2, "locals oop mask generation error");
280 st.print("%d", v1 ? 1 : 0);
281 }
282 st.cr();
283
284 st.print("Stack (%d): ", stack_top);
285 for(int j = 0; j < stack_top; j++) {
286 bool v1 = is_oop(max_locals + j) ? true : false;
287 bool v2 = stack[j].is_reference();
288 assert(v1 == v2, "stack oop mask generation error");
289 st.print("%d", v1 ? 1 : 0);
290 }
291 st.cr();
292 return true;
293 }
294
295 void OopMapCacheEntry::allocate_bit_mask() {
296 if (mask_size() > small_mask_limit) {
297 assert(_bit_mask[0] == 0, "bit mask should be new or just flushed");
298 _bit_mask[0] = (intptr_t)
299 NEW_C_HEAP_ARRAY(uintptr_t, mask_word_size(), mtClass);
300 }
301 }
302
303 void OopMapCacheEntry::deallocate_bit_mask() {
304 if (mask_size() > small_mask_limit && _bit_mask[0] != 0) {
305 assert(!Thread::current()->resource_area()->contains((void*)_bit_mask[0]),
306 "This bit mask should not be in the resource area");
307 FREE_C_HEAP_ARRAY(uintptr_t, _bit_mask[0]);
308 debug_only(_bit_mask[0] = 0;)
309 }
310 }
311
312
313 void OopMapCacheEntry::fill_for_native(const methodHandle& mh) {
314 assert(mh->is_native(), "method must be native method");
315 set_mask_size(mh->size_of_parameters() * bits_per_entry);
316 allocate_bit_mask();
317 // fill mask for parameters
318 MaskFillerForNative mf(mh, bit_mask(), mask_size());
319 mf.generate();
320 }
321
322
323 void OopMapCacheEntry::fill(const methodHandle& method, int bci) {
324 HandleMark hm;
325 // Flush entry to deallocate an existing entry
326 flush();
327 set_method(method());
328 set_bci(bci);
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 EXCEPTION_MARK;
335 OopMapForCacheEntry gen(method, bci, this);
336 gen.compute_map(CATCH);
337 }
338 }
339
340
341 void OopMapCacheEntry::set_mask(CellTypeState *vars, CellTypeState *stack, int stack_top) {
342 // compute bit mask size
343 int max_locals = method()->max_locals();
344 int n_entries = max_locals + stack_top;
345 set_mask_size(n_entries * bits_per_entry);
346 allocate_bit_mask();
347 set_expression_stack_size(stack_top);
348
349 // compute bits
350 int word_index = 0;
351 uintptr_t value = 0;
352 uintptr_t mask = 1;
353
354 CellTypeState* cell = vars;
355 for (int entry_index = 0; entry_index < n_entries; entry_index++, mask <<= bits_per_entry, cell++) {
356 // store last word
357 if (mask == 0) {
358 bit_mask()[word_index++] = value;
359 value = 0;
360 mask = 1;
361 }
362
363 // switch to stack when done with locals
364 if (entry_index == max_locals) {
365 cell = stack;
366 }
367
368 // set oop bit
369 if (cell->is_reference()) {
370 value |= (mask << oop_bit_number );
371 }
372
373 // set dead bit
374 if (!cell->is_live()) {
375 value |= (mask << dead_bit_number);
376 assert(!cell->is_reference(), "dead value marked as oop");
377 }
378 }
379
380 // make sure last word is stored
381 bit_mask()[word_index] = value;
382
383 // verify bit mask
384 assert(verify_mask(vars, stack, max_locals, stack_top), "mask could not be verified");
385 }
386
387 void OopMapCacheEntry::flush() {
388 deallocate_bit_mask();
389 initialize();
390 }
391
392
393 // Implementation of OopMapCache
394
395 void InterpreterOopMap::resource_copy(OopMapCacheEntry* from) {
396 assert(_resource_allocate_bit_mask,
397 "Should not resource allocate the _bit_mask");
398
399 set_method(from->method());
400 set_bci(from->bci());
401 set_mask_size(from->mask_size());
402 set_expression_stack_size(from->expression_stack_size());
403
404 // Is the bit mask contained in the entry?
405 if (from->mask_size() <= small_mask_limit) {
406 memcpy((void *)_bit_mask, (void *)from->_bit_mask,
407 mask_word_size() * BytesPerWord);
408 } else {
409 // The expectation is that this InterpreterOopMap is a recently created
410 // and empty. It is used to get a copy of a cached entry.
411 // If the bit mask has a value, it should be in the
412 // resource area.
413 assert(_bit_mask[0] == 0 ||
414 Thread::current()->resource_area()->contains((void*)_bit_mask[0]),
415 "The bit mask should have been allocated from a resource area");
416 // Allocate the bit_mask from a Resource area for performance. Allocating
417 // from the C heap as is done for OopMapCache has a significant
418 // performance impact.
419 _bit_mask[0] = (uintptr_t) NEW_RESOURCE_ARRAY(uintptr_t, mask_word_size());
420 assert(_bit_mask[0] != 0, "bit mask was not allocated");
421 memcpy((void*) _bit_mask[0], (void*) from->_bit_mask[0],
422 mask_word_size() * BytesPerWord);
423 }
424 }
425
426 inline unsigned int OopMapCache::hash_value_for(const methodHandle& method, int bci) const {
427 // We use method->code_size() rather than method->identity_hash() below since
428 // the mark may not be present if a pointer to the method is already reversed.
429 return ((unsigned int) bci)
430 ^ ((unsigned int) method->max_locals() << 2)
431 ^ ((unsigned int) method->code_size() << 4)
432 ^ ((unsigned int) method->size_of_parameters() << 6);
433 }
434
435 OopMapCacheEntry* volatile OopMapCache::_old_entries = NULL;
436
437 OopMapCache::OopMapCache() {
438 _array = NEW_C_HEAP_ARRAY(OopMapCacheEntry*, _size, mtClass);
439 for(int i = 0; i < _size; i++) _array[i] = NULL;
440 }
441
442
443 OopMapCache::~OopMapCache() {
444 assert(_array != NULL, "sanity check");
445 // Deallocate oop maps that are allocated out-of-line
446 flush();
447 // Deallocate array
448 FREE_C_HEAP_ARRAY(OopMapCacheEntry*, _array);
449 }
450
451 OopMapCacheEntry* OopMapCache::entry_at(int i) const {
452 return OrderAccess::load_acquire(&(_array[i % _size]));
453 }
454
455 bool OopMapCache::put_at(int i, OopMapCacheEntry* entry, OopMapCacheEntry* old) {
456 return Atomic::cmpxchg(entry, &_array[i % _size], old) == old;
457 }
458
459 void OopMapCache::flush() {
460 for (int i = 0; i < _size; i++) {
461 OopMapCacheEntry* entry = _array[i];
462 if (entry != NULL) {
463 _array[i] = NULL; // no barrier, only called in OopMapCache destructor
464 entry->flush();
465 FREE_C_HEAP_OBJ(entry);
466 }
467 }
468 }
469
470 void OopMapCache::flush_obsolete_entries() {
471 assert(SafepointSynchronize::is_at_safepoint(), "called by RedefineClasses in a safepoint");
472 for (int i = 0; i < _size; i++) {
473 OopMapCacheEntry* entry = _array[i];
474 if (entry != NULL && !entry->is_empty() && entry->method()->is_old()) {
475 // Cache entry is occupied by an old redefined method and we don't want
476 // to pin it down so flush the entry.
477 if (log_is_enabled(Debug, redefine, class, oopmap)) {
478 ResourceMark rm;
479 log_debug(redefine, class, interpreter, oopmap)
480 ("flush: %s(%s): cached entry @%d",
481 entry->method()->name()->as_C_string(), entry->method()->signature()->as_C_string(), i);
482 }
483 _array[i] = NULL;
484 entry->flush();
485 FREE_C_HEAP_OBJ(entry);
486 }
487 }
488 }
489
490 // Called by GC for thread root scan during a safepoint only. The other interpreted frame oopmaps
491 // are generated locally and not cached.
492 void OopMapCache::lookup(const methodHandle& method,
493 int bci,
494 InterpreterOopMap* entry_for) {
495 assert(SafepointSynchronize::is_at_safepoint(), "called by GC in a safepoint");
496 int probe = hash_value_for(method, bci);
497 int i;
498 OopMapCacheEntry* entry = NULL;
499
500 if (log_is_enabled(Debug, interpreter, oopmap)) {
501 static int count = 0;
502 ResourceMark rm;
503 log_debug(interpreter, oopmap)
504 ("%d - Computing oopmap at bci %d for %s at hash %d", ++count, bci,
505 method()->name_and_sig_as_C_string(), probe);
506 }
507
508 // Search hashtable for match
509 for(i = 0; i < _probe_depth; i++) {
510 entry = entry_at(probe + i);
511 if (entry != NULL && !entry->is_empty() && entry->match(method, bci)) {
512 entry_for->resource_copy(entry);
513 assert(!entry_for->is_empty(), "A non-empty oop map should be returned");
514 log_debug(interpreter, oopmap)("- found at hash %d", probe + i);
515 return;
516 }
517 }
518
519 // Entry is not in hashtable.
520 // Compute entry
521
522 OopMapCacheEntry* tmp = NEW_C_HEAP_OBJ(OopMapCacheEntry, mtClass);
523 tmp->initialize();
524 tmp->fill(method, bci);
525 entry_for->resource_copy(tmp);
526
527 if (method->should_not_be_cached()) {
528 // It is either not safe or not a good idea to cache this Method*
529 // at this time. We give the caller of lookup() a copy of the
530 // interesting info via parameter entry_for, but we don't add it to
531 // the cache. See the gory details in Method*.cpp.
532 FREE_C_HEAP_OBJ(tmp);
533 return;
534 }
535
536 // First search for an empty slot
537 for(i = 0; i < _probe_depth; i++) {
538 entry = entry_at(probe + i);
539 if (entry == NULL) {
540 if (put_at(probe + i, tmp, NULL)) {
541 assert(!entry_for->is_empty(), "A non-empty oop map should be returned");
542 return;
543 }
544 }
545 }
546
547 log_debug(interpreter, oopmap)("*** collision in oopmap cache - flushing item ***");
548
549 // No empty slot (uncommon case). Use (some approximation of a) LRU algorithm
550 // where the first entry in the collision array is replaced with the new one.
551 OopMapCacheEntry* old = entry_at(probe + 0);
552 if (put_at(probe + 0, tmp, old)) {
553 enqueue_for_cleanup(old);
554 } else {
555 enqueue_for_cleanup(tmp);
556 }
557
558 assert(!entry_for->is_empty(), "A non-empty oop map should be returned");
559 return;
560 }
561
562 void OopMapCache::enqueue_for_cleanup(OopMapCacheEntry* entry) {
563 bool success = false;
564 OopMapCacheEntry* head;
565 do {
566 head = _old_entries;
567 entry->_next = head;
568 success = Atomic::cmpxchg(entry, &_old_entries, head) == head;
569 } while (!success);
570
571 if (log_is_enabled(Debug, interpreter, oopmap)) {
572 ResourceMark rm;
573 log_debug(interpreter, oopmap)("enqueue %s at bci %d for cleanup",
574 entry->method()->name_and_sig_as_C_string(), entry->bci());
575 }
576 }
577
578 // This is called after GC threads are done and nothing is accessing the old_entries
579 // list, so no synchronization needed.
580 void OopMapCache::cleanup_old_entries() {
581 OopMapCacheEntry* entry = _old_entries;
582 _old_entries = NULL;
583 while (entry != NULL) {
584 if (log_is_enabled(Debug, interpreter, oopmap)) {
585 ResourceMark rm;
586 log_debug(interpreter, oopmap)("cleanup entry %s at bci %d",
587 entry->method()->name_and_sig_as_C_string(), entry->bci());
588 }
589 OopMapCacheEntry* next = entry->_next;
590 entry->flush();
591 FREE_C_HEAP_OBJ(entry);
592 entry = next;
593 }
594 }
595
596 void OopMapCache::compute_one_oop_map(const methodHandle& method, int bci, InterpreterOopMap* entry) {
597 // Due to the invariants above it's tricky to allocate a temporary OopMapCacheEntry on the stack
598 OopMapCacheEntry* tmp = NEW_C_HEAP_ARRAY(OopMapCacheEntry, 1, mtClass);
599 tmp->initialize();
600 tmp->fill(method, bci);
601 entry->resource_copy(tmp);
602 FREE_C_HEAP_ARRAY(OopMapCacheEntry, tmp);
603 }