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   _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   Log(interpreter, oopmap) logv;
281   LogStream st(logv.trace());
282 
283   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()  ? true : false;
287     assert(v1 == v2, "locals oop mask generation error");
288     st.print("%d", v1 ? 1 : 0);
289   }
290   st.cr();
291 
292   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() ? true : false;
296     assert(v1 == v2, "stack oop mask generation error");
297     st.print("%d", v1 ? 1 : 0);
298   }
299   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 }
--- EOF ---