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()  ? true : false;
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() ? true : false;
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 }
--- EOF ---