1 /*
   2  * Copyright (c) 1997, 2019, 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 
 250   MaskFillerForNative(const methodHandle& method, uintptr_t* mask, int size) : NativeSignatureIterator(method) {
 251     _mask   = mask;
 252     _size   = size;
 253     // initialize with 0
 254     int i = (size + BitsPerWord - 1) / BitsPerWord;
 255     while (i-- > 0) _mask[i] = 0;
 256   }
 257 
 258   void generate() {
 259     NativeSignatureIterator::iterate();
 260   }
 261 };
 262 
 263 bool OopMapCacheEntry::verify_mask(CellTypeState* vars, CellTypeState* stack, int max_locals, int stack_top) {
 264   // Check mask includes map
 265   VerifyClosure blk(this);
 266   iterate_oop(&blk);
 267   if (blk.failed()) return false;
 268 
 269   // Check if map is generated correctly
 270   // (Use ?: operator to make sure all 'true' & 'false' are represented exactly the same so we can use == afterwards)
 271   Log(interpreter, oopmap) logv;
 272   LogStream st(logv.trace());
 273 
 274   st.print("Locals (%d): ", max_locals);
 275   for(int i = 0; i < max_locals; i++) {
 276     bool v1 = is_oop(i)               ? true : false;
 277     bool v2 = vars[i].is_reference()  ? true : false;
 278     assert(v1 == v2, "locals oop mask generation error");
 279     st.print("%d", v1 ? 1 : 0);
 280   }
 281   st.cr();
 282 
 283   st.print("Stack (%d): ", stack_top);
 284   for(int j = 0; j < stack_top; j++) {
 285     bool v1 = is_oop(max_locals + j)  ? true : false;
 286     bool v2 = stack[j].is_reference() ? true : false;
 287     assert(v1 == v2, "stack oop mask generation error");
 288     st.print("%d", v1 ? 1 : 0);
 289   }
 290   st.cr();
 291   return true;
 292 }
 293 
 294 void OopMapCacheEntry::allocate_bit_mask() {
 295   if (mask_size() > small_mask_limit) {
 296     assert(_bit_mask[0] == 0, "bit mask should be new or just flushed");
 297     _bit_mask[0] = (intptr_t)
 298       NEW_C_HEAP_ARRAY(uintptr_t, mask_word_size(), mtClass);
 299   }
 300 }
 301 
 302 void OopMapCacheEntry::deallocate_bit_mask() {
 303   if (mask_size() > small_mask_limit && _bit_mask[0] != 0) {
 304     assert(!Thread::current()->resource_area()->contains((void*)_bit_mask[0]),
 305       "This bit mask should not be in the resource area");
 306     FREE_C_HEAP_ARRAY(uintptr_t, _bit_mask[0]);
 307     debug_only(_bit_mask[0] = 0;)
 308   }
 309 }
 310 
 311 
 312 void OopMapCacheEntry::fill_for_native(const methodHandle& mh) {
 313   assert(mh->is_native(), "method must be native method");
 314   set_mask_size(mh->size_of_parameters() * bits_per_entry);
 315   allocate_bit_mask();
 316   // fill mask for parameters
 317   MaskFillerForNative mf(mh, bit_mask(), mask_size());
 318   mf.generate();
 319 }
 320 
 321 
 322 void OopMapCacheEntry::fill(const methodHandle& method, int bci) {
 323   HandleMark hm;
 324   // Flush entry to deallocate an existing entry
 325   flush();
 326   set_method(method());
 327   set_bci(bci);
 328   if (method->is_native()) {
 329     // Native method activations have oops only among the parameters and one
 330     // extra oop following the parameters (the mirror for static native methods).
 331     fill_for_native(method);
 332   } else {
 333     EXCEPTION_MARK;
 334     OopMapForCacheEntry gen(method, bci, this);
 335     gen.compute_map(CATCH);
 336   }
 337 }
 338 
 339 
 340 void OopMapCacheEntry::set_mask(CellTypeState *vars, CellTypeState *stack, int stack_top) {
 341   // compute bit mask size
 342   int max_locals = method()->max_locals();
 343   int n_entries = max_locals + stack_top;
 344   set_mask_size(n_entries * bits_per_entry);
 345   allocate_bit_mask();
 346   set_expression_stack_size(stack_top);
 347 
 348   // compute bits
 349   int word_index = 0;
 350   uintptr_t value = 0;
 351   uintptr_t mask = 1;
 352 
 353   CellTypeState* cell = vars;
 354   for (int entry_index = 0; entry_index < n_entries; entry_index++, mask <<= bits_per_entry, cell++) {
 355     // store last word
 356     if (mask == 0) {
 357       bit_mask()[word_index++] = value;
 358       value = 0;
 359       mask = 1;
 360     }
 361 
 362     // switch to stack when done with locals
 363     if (entry_index == max_locals) {
 364       cell = stack;
 365     }
 366 
 367     // set oop bit
 368     if ( cell->is_reference()) {
 369       value |= (mask << oop_bit_number );
 370     }
 371 
 372     // set dead bit
 373     if (!cell->is_live()) {
 374       value |= (mask << dead_bit_number);
 375       assert(!cell->is_reference(), "dead value marked as oop");
 376     }
 377   }
 378 
 379   // make sure last word is stored
 380   bit_mask()[word_index] = value;
 381 
 382   // verify bit mask
 383   assert(verify_mask(vars, stack, max_locals, stack_top), "mask could not be verified");
 384 }
 385 
 386 void OopMapCacheEntry::flush() {
 387   deallocate_bit_mask();
 388   initialize();
 389 }
 390 
 391 
 392 // Implementation of OopMapCache
 393 
 394 void InterpreterOopMap::resource_copy(OopMapCacheEntry* from) {
 395   assert(_resource_allocate_bit_mask,
 396     "Should not resource allocate the _bit_mask");
 397 
 398   set_method(from->method());
 399   set_bci(from->bci());
 400   set_mask_size(from->mask_size());
 401   set_expression_stack_size(from->expression_stack_size());
 402 
 403   // Is the bit mask contained in the entry?
 404   if (from->mask_size() <= small_mask_limit) {
 405     memcpy((void *)_bit_mask, (void *)from->_bit_mask,
 406       mask_word_size() * BytesPerWord);
 407   } else {
 408     // The expectation is that this InterpreterOopMap is a recently created
 409     // and empty. It is used to get a copy of a cached entry.
 410     // If the bit mask has a value, it should be in the
 411     // resource area.
 412     assert(_bit_mask[0] == 0 ||
 413       Thread::current()->resource_area()->contains((void*)_bit_mask[0]),
 414       "The bit mask should have been allocated from a resource area");
 415     // Allocate the bit_mask from a Resource area for performance.  Allocating
 416     // from the C heap as is done for OopMapCache has a significant
 417     // performance impact.
 418     _bit_mask[0] = (uintptr_t) NEW_RESOURCE_ARRAY(uintptr_t, mask_word_size());
 419     assert(_bit_mask[0] != 0, "bit mask was not allocated");
 420     memcpy((void*) _bit_mask[0], (void*) from->_bit_mask[0],
 421       mask_word_size() * BytesPerWord);
 422   }
 423 }
 424 
 425 inline unsigned int OopMapCache::hash_value_for(const methodHandle& method, int bci) const {
 426   // We use method->code_size() rather than method->identity_hash() below since
 427   // the mark may not be present if a pointer to the method is already reversed.
 428   return   ((unsigned int) bci)
 429          ^ ((unsigned int) method->max_locals()         << 2)
 430          ^ ((unsigned int) method->code_size()          << 4)
 431          ^ ((unsigned int) method->size_of_parameters() << 6);
 432 }
 433 
 434 OopMapCacheEntry* volatile OopMapCache::_old_entries = NULL;
 435 
 436 OopMapCache::OopMapCache() {
 437   _array  = NEW_C_HEAP_ARRAY(OopMapCacheEntry*, _size, mtClass);
 438   for(int i = 0; i < _size; i++) _array[i] = NULL;
 439 }
 440 
 441 
 442 OopMapCache::~OopMapCache() {
 443   assert(_array != NULL, "sanity check");
 444   // Deallocate oop maps that are allocated out-of-line
 445   flush();
 446   // Deallocate array
 447   FREE_C_HEAP_ARRAY(OopMapCacheEntry*, _array);
 448 }
 449 
 450 OopMapCacheEntry* OopMapCache::entry_at(int i) const {
 451   return OrderAccess::load_acquire(&(_array[i % _size]));
 452 }
 453 
 454 bool OopMapCache::put_at(int i, OopMapCacheEntry* entry, OopMapCacheEntry* old) {
 455   return Atomic::cmpxchg(entry, &_array[i % _size], old) == old;
 456 }
 457 
 458 void OopMapCache::flush() {
 459   for (int i = 0; i < _size; i++) {
 460     OopMapCacheEntry* entry = _array[i];
 461     if (entry != NULL) {
 462       _array[i] = NULL;  // no barrier, only called in OopMapCache destructor
 463       entry->flush();
 464       FREE_C_HEAP_OBJ(entry);
 465     }
 466   }
 467 }
 468 
 469 void OopMapCache::flush_obsolete_entries() {
 470   assert(SafepointSynchronize::is_at_safepoint(), "called by RedefineClasses in a safepoint");
 471   for (int i = 0; i < _size; i++) {
 472     OopMapCacheEntry* entry = _array[i];
 473     if (entry != NULL && !entry->is_empty() && entry->method()->is_old()) {
 474       // Cache entry is occupied by an old redefined method and we don't want
 475       // to pin it down so flush the entry.
 476       if (log_is_enabled(Debug, redefine, class, oopmap)) {
 477         ResourceMark rm;
 478         log_debug(redefine, class, interpreter, oopmap)
 479           ("flush: %s(%s): cached entry @%d",
 480            entry->method()->name()->as_C_string(), entry->method()->signature()->as_C_string(), i);
 481       }
 482       _array[i] = NULL;
 483       entry->flush();
 484       FREE_C_HEAP_OBJ(entry);
 485     }
 486   }
 487 }
 488 
 489 // Called by GC for thread root scan during a safepoint only.  The other interpreted frame oopmaps
 490 // are generated locally and not cached.
 491 void OopMapCache::lookup(const methodHandle& method,
 492                          int bci,
 493                          InterpreterOopMap* entry_for) {
 494   assert(SafepointSynchronize::is_at_safepoint(), "called by GC in a safepoint");
 495   int probe = hash_value_for(method, bci);
 496   int i;
 497   OopMapCacheEntry* entry = NULL;
 498 
 499   if (log_is_enabled(Debug, interpreter, oopmap)) {
 500     static int count = 0;
 501     ResourceMark rm;
 502     log_debug(interpreter, oopmap)
 503           ("%d - Computing oopmap at bci %d for %s at hash %d", ++count, bci,
 504            method()->name_and_sig_as_C_string(), probe);
 505   }
 506 
 507   // Search hashtable for match
 508   for(i = 0; i < _probe_depth; i++) {
 509     entry = entry_at(probe + i);
 510     if (entry != NULL && !entry->is_empty() && entry->match(method, bci)) {
 511       entry_for->resource_copy(entry);
 512       assert(!entry_for->is_empty(), "A non-empty oop map should be returned");
 513       log_debug(interpreter, oopmap)("- found at hash %d", probe + i);
 514       return;
 515     }
 516   }
 517 
 518   // Entry is not in hashtable.
 519   // Compute entry
 520 
 521   OopMapCacheEntry* tmp = NEW_C_HEAP_OBJ(OopMapCacheEntry, mtClass);
 522   tmp->initialize();
 523   tmp->fill(method, bci);
 524   entry_for->resource_copy(tmp);
 525 
 526   if (method->should_not_be_cached()) {
 527     // It is either not safe or not a good idea to cache this Method*
 528     // at this time. We give the caller of lookup() a copy of the
 529     // interesting info via parameter entry_for, but we don't add it to
 530     // the cache. See the gory details in Method*.cpp.
 531     FREE_C_HEAP_OBJ(tmp);
 532     return;
 533   }
 534 
 535   // First search for an empty slot
 536   for(i = 0; i < _probe_depth; i++) {
 537     entry = entry_at(probe + i);
 538     if (entry == NULL) {
 539       if (put_at(probe + i, tmp, NULL)) {
 540         assert(!entry_for->is_empty(), "A non-empty oop map should be returned");
 541         return;
 542       }
 543     }
 544   }
 545 
 546   log_debug(interpreter, oopmap)("*** collision in oopmap cache - flushing item ***");
 547 
 548   // No empty slot (uncommon case). Use (some approximation of a) LRU algorithm
 549   // where the first entry in the collision array is replaced with the new one.
 550   OopMapCacheEntry* old = entry_at(probe + 0);
 551   if (put_at(probe + 0, tmp, old)) {
 552     enqueue_for_cleanup(old);
 553   } else {
 554     enqueue_for_cleanup(tmp);
 555   }
 556 
 557   assert(!entry_for->is_empty(), "A non-empty oop map should be returned");
 558   return;
 559 }
 560 
 561 void OopMapCache::enqueue_for_cleanup(OopMapCacheEntry* entry) {
 562   bool success = false;
 563   OopMapCacheEntry* head;
 564   do {
 565     head = _old_entries;
 566     entry->_next = head;
 567     success = Atomic::cmpxchg(entry, &_old_entries, head) == head;
 568   } while (!success);
 569 
 570   if (log_is_enabled(Debug, interpreter, oopmap)) {
 571     ResourceMark rm;
 572     log_debug(interpreter, oopmap)("enqueue %s at bci %d for cleanup",
 573                           entry->method()->name_and_sig_as_C_string(), entry->bci());
 574   }
 575 }
 576 
 577 // This is called after GC threads are done and nothing is accessing the old_entries
 578 // list, so no synchronization needed.
 579 void OopMapCache::cleanup_old_entries() {
 580   OopMapCacheEntry* entry = _old_entries;
 581   _old_entries = NULL;
 582   while (entry != NULL) {
 583     if (log_is_enabled(Debug, interpreter, oopmap)) {
 584       ResourceMark rm;
 585       log_debug(interpreter, oopmap)("cleanup entry %s at bci %d",
 586                           entry->method()->name_and_sig_as_C_string(), entry->bci());
 587     }
 588     OopMapCacheEntry* next = entry->_next;
 589     entry->flush();
 590     FREE_C_HEAP_OBJ(entry);
 591     entry = next;
 592   }
 593 }
 594 
 595 void OopMapCache::compute_one_oop_map(const methodHandle& method, int bci, InterpreterOopMap* entry) {
 596   // Due to the invariants above it's tricky to allocate a temporary OopMapCacheEntry on the stack
 597   OopMapCacheEntry* tmp = NEW_C_HEAP_OBJ(OopMapCacheEntry, mtClass);
 598   tmp->initialize();
 599   tmp->fill(method, bci);
 600   entry->resource_copy(tmp);
 601   FREE_C_HEAP_OBJ(tmp);
 602 }