1 /*

     2  * Copyright 1997-2006 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    20  * CA 95054 USA or visit www.sun.com if you need additional information or

    21  * have any questions.

    22  *

    23  */

    24 

    25 # include "incls/_precompiled.incl"

    26 # include "incls/_oopMapCache.cpp.incl"

    27 

    28 class OopMapCacheEntry: private InterpreterOopMap {

    29   friend class InterpreterOopMap;

    30   friend class OopMapForCacheEntry;

    31   friend class OopMapCache;

    32   friend class VerifyClosure;

    33 

    34  protected:

    35   // Initialization

    36   void fill(methodHandle method, int bci);

    37   // fills the bit mask for native calls

    38   void fill_for_native(methodHandle method);

    39   void set_mask(CellTypeState* vars, CellTypeState* stack, int stack_top);

    40 

    41   // Deallocate bit masks and initialize fields

    42   void flush();

    43 

    44  private:

    45   void allocate_bit_mask();   // allocates the bit mask on C heap f necessary

    46   void deallocate_bit_mask(); // allocates the bit mask on C heap f necessary

    47   bool verify_mask(CellTypeState *vars, CellTypeState *stack, int max_locals, int stack_top);

    48 

    49  public:

    50   OopMapCacheEntry() : InterpreterOopMap() {

    51 #ifdef ASSERT

    52      _resource_allocate_bit_mask = false;

    53 #endif

    54   }

    55 };

    56 

    57 

    58 // Implementation of OopMapForCacheEntry

    59 // (subclass of GenerateOopMap, initializes an OopMapCacheEntry for a given method and bci)

    60 

    61 class OopMapForCacheEntry: public GenerateOopMap {

    62   OopMapCacheEntry *_entry;

    63   int               _bci;

    64   int               _stack_top;

    65 

    66   virtual bool report_results() const     { return false; }

    67   virtual bool possible_gc_point          (BytecodeStream *bcs);

    68   virtual void fill_stackmap_prolog       (int nof_gc_points);

    69   virtual void fill_stackmap_epilog       ();

    70   virtual void fill_stackmap_for_opcodes  (BytecodeStream *bcs,

    71                                            CellTypeState* vars,

    72                                            CellTypeState* stack,

    73                                            int stack_top);

    74   virtual void fill_init_vars             (GrowableArray<intptr_t> *init_vars);

    75 

    76  public:

    77   OopMapForCacheEntry(methodHandle method, int bci, OopMapCacheEntry *entry);

    78 

    79   // Computes stack map for (method,bci) and initialize entry

    80   void compute_map(TRAPS);

    81   int  size();

    82 };

    83 

    84 

    85 OopMapForCacheEntry::OopMapForCacheEntry(methodHandle method, int bci, OopMapCacheEntry* entry) : GenerateOopMap(method) {

    86   _bci       = bci;

    87   _entry     = entry;

    88   _stack_top = -1;

    89 }

    90 

    91 

    92 void OopMapForCacheEntry::compute_map(TRAPS) {

    93   assert(!method()->is_native(), "cannot compute oop map for native methods");

    94   // First check if it is a method where the stackmap is always empty

    95   if (method()->code_size() == 0 || method()->max_locals() + method()->max_stack() == 0) {

    96     _entry->set_mask_size(0);

    97   } else {

    98     ResourceMark rm;

    99     GenerateOopMap::compute_map(CATCH);

   100     result_for_basicblock(_bci);

   101   }

   102 }

   103 

   104 

   105 bool OopMapForCacheEntry::possible_gc_point(BytecodeStream *bcs) {

   106   return false; // We are not reporting any result. We call result_for_basicblock directly

   107 }

   108 

   109 

   110 void OopMapForCacheEntry::fill_stackmap_prolog(int nof_gc_points) {

   111   // Do nothing

   112 }

   113 

   114 

   115 void OopMapForCacheEntry::fill_stackmap_epilog() {

   116   // Do nothing

   117 }

   118 

   119 

   120 void OopMapForCacheEntry::fill_init_vars(GrowableArray<intptr_t> *init_vars) {

   121   // Do nothing

   122 }

   123 

   124 

   125 void OopMapForCacheEntry::fill_stackmap_for_opcodes(BytecodeStream *bcs,

   126                                                     CellTypeState* vars,

   127                                                     CellTypeState* stack,

   128                                                     int stack_top) {

   129   // Only interested in one specific bci

   130   if (bcs->bci() == _bci) {

   131     _entry->set_mask(vars, stack, stack_top);

   132     _stack_top = stack_top;

   133   }

   134 }

   135 

   136 

   137 int OopMapForCacheEntry::size() {

   138   assert(_stack_top != -1, "compute_map must be called first");

   139   return ((method()->is_static()) ? 0 : 1) + method()->max_locals() + _stack_top;

   140 }

   141 

   142 

   143 // Implementation of InterpreterOopMap and OopMapCacheEntry

   144 

   145 class VerifyClosure : public OffsetClosure {

   146  private:

   147   OopMapCacheEntry* _entry;

   148   bool              _failed;

   149 

   150  public:

   151   VerifyClosure(OopMapCacheEntry* entry)         { _entry = entry; _failed = false; }

   152   void offset_do(int offset)                     { if (!_entry->is_oop(offset)) _failed = true; }

   153   bool failed() const                            { return _failed; }

   154 };

   155 

   156 InterpreterOopMap::InterpreterOopMap() {

   157   initialize();

   158 #ifdef ASSERT

   159   _resource_allocate_bit_mask = true;

   160 #endif

   161 }

   162 

   163 InterpreterOopMap::~InterpreterOopMap() {

   164   // The expection is that the bit mask was allocated

   165   // last in this resource area.  That would make the free of the

   166   // bit_mask effective (see how FREE_RESOURCE_ARRAY does a free).

   167   // If it was not allocated last, there is not a correctness problem

   168   // but the space for the bit_mask is not freed.

   169   assert(_resource_allocate_bit_mask, "Trying to free C heap space");

   170   if (mask_size() > small_mask_limit) {

   171     FREE_RESOURCE_ARRAY(uintptr_t, _bit_mask[0], mask_word_size());

   172   }

   173 }

   174 

   175 bool InterpreterOopMap::is_empty() {

   176   bool result = _method == NULL;

   177   assert(_method != NULL || (_bci == 0 &&

   178     (_mask_size == 0 || _mask_size == USHRT_MAX) &&

   179     _bit_mask[0] == 0), "Should be completely empty");

   180   return result;

   181 }

   182 

   183 void InterpreterOopMap::initialize() {

   184   _method    = NULL;

   185   _mask_size = USHRT_MAX;  // This value should cause a failure quickly

   186   _bci       = 0;

   187   _expression_stack_size = 0;

   188   for (int i = 0; i < N; i++) _bit_mask[i] = 0;

   189 }

   190 

   191 

   192 void InterpreterOopMap::oop_iterate(OopClosure *blk) {

   193   if (method() != NULL) {

   194     blk->do_oop((oop*) &_method);

   195   }

   196 }

   197 

   198 void InterpreterOopMap::oop_iterate(OopClosure *blk, MemRegion mr) {

   199   if (method() != NULL && mr.contains(&_method)) {

   200     blk->do_oop((oop*) &_method);

   201   }

   202 }

   203 

   204 

   205 

   206 void InterpreterOopMap::iterate_oop(OffsetClosure* oop_closure) {

   207   int n = number_of_entries();

   208   int word_index = 0;

   209   uintptr_t value = 0;

   210   uintptr_t mask = 0;

   211   // iterate over entries

   212   for (int i = 0; i < n; i++, mask <<= bits_per_entry) {

   213     // get current word

   214     if (mask == 0) {

   215       value = bit_mask()[word_index++];

   216       mask = 1;

   217     }

   218     // test for oop

   219     if ((value & (mask << oop_bit_number)) != 0) oop_closure->offset_do(i);

   220   }

   221 }

   222 

   223 void InterpreterOopMap::verify() {

   224   // If we are doing mark sweep _method may not have a valid header

   225   // $$$ This used to happen only for m/s collections; we might want to

   226   // think of an appropriate generalization of this distinction.

   227   guarantee(Universe::heap()->is_gc_active() ||

   228             _method->is_oop_or_null(), "invalid oop in oopMapCache")

   229 }

   230 

   231 #ifdef ENABLE_ZAP_DEAD_LOCALS

   232 

   233 void InterpreterOopMap::iterate_all(OffsetClosure* oop_closure, OffsetClosure* value_closure, OffsetClosure* dead_closure) {

   234   int n = number_of_entries();

   235   int word_index = 0;

   236   uintptr_t value = 0;

   237   uintptr_t mask = 0;

   238   // iterate over entries

   239   for (int i = 0; i < n; i++, mask <<= bits_per_entry) {

   240     // get current word

   241     if (mask == 0) {

   242       value = bit_mask()[word_index++];

   243       mask = 1;

   244     }

   245     // test for dead values  & oops, and for live values

   246          if ((value & (mask << dead_bit_number)) != 0)  dead_closure->offset_do(i); // call this for all dead values or oops

   247     else if ((value & (mask <<  oop_bit_number)) != 0)   oop_closure->offset_do(i); // call this for all live oops

   248     else                                               value_closure->offset_do(i); // call this for all live values

   249   }

   250 }

   251 

   252 #endif

   253 

   254 

   255 void InterpreterOopMap::print() {

   256   int n = number_of_entries();

   257   tty->print("oop map for ");

   258   method()->print_value();

   259   tty->print(" @ %d = [%d] { ", bci(), n);

   260   for (int i = 0; i < n; i++) {

   261 #ifdef ENABLE_ZAP_DEAD_LOCALS

   262     if (is_dead(i)) tty->print("%d+ ", i);

   263     else

   264 #endif

   265     if (is_oop(i)) tty->print("%d ", i);

   266   }

   267   tty->print_cr("}");

   268 }

   269 

   270 class MaskFillerForNative: public NativeSignatureIterator {

   271  private:

   272   uintptr_t * _mask;                             // the bit mask to be filled

   273   int         _size;                             // the mask size in bits

   274 

   275   void set_one(int i) {

   276     i *= InterpreterOopMap::bits_per_entry;

   277     assert(0 <= i && i < _size, "offset out of bounds");

   278     _mask[i / BitsPerWord] |= (((uintptr_t) 1 << InterpreterOopMap::oop_bit_number) << (i % BitsPerWord));

   279   }

   280 

   281  public:

   282   void pass_int()                                { /* ignore */ }

   283   void pass_long()                               { /* ignore */ }

   284 #ifdef _LP64

   285   void pass_float()                              { /* ignore */ }

   286 #endif

   287   void pass_double()                             { /* ignore */ }

   288   void pass_object()                             { set_one(offset()); }

   289 

   290   MaskFillerForNative(methodHandle method, uintptr_t* mask, int size) : NativeSignatureIterator(method) {

   291     _mask   = mask;

   292     _size   = size;

   293     // initialize with 0

   294     int i = (size + BitsPerWord - 1) / BitsPerWord;

   295     while (i-- > 0) _mask[i] = 0;

   296   }

   297 

   298   void generate() {

   299     NativeSignatureIterator::iterate();

   300   }

   301 };

   302 

   303 bool OopMapCacheEntry::verify_mask(CellTypeState* vars, CellTypeState* stack, int max_locals, int stack_top) {

   304   // Check mask includes map

   305   VerifyClosure blk(this);

   306   iterate_oop(&blk);

   307   if (blk.failed()) return false;

   308 

   309   // Check if map is generated correctly

   310   // (Use ?: operator to make sure all 'true' & 'false' are represented exactly the same so we can use == afterwards)

   311   if (TraceOopMapGeneration && Verbose) tty->print("Locals (%d): ", max_locals);

   312 

   313   for(int i = 0; i < max_locals; i++) {

   314     bool v1 = is_oop(i)               ? true : false;

   315     bool v2 = vars[i].is_reference()  ? true : false;

   316     assert(v1 == v2, "locals oop mask generation error");

   317     if (TraceOopMapGeneration && Verbose) tty->print("%d", v1 ? 1 : 0);

   318 #ifdef ENABLE_ZAP_DEAD_LOCALS

   319     bool v3 = is_dead(i)              ? true : false;

   320     bool v4 = !vars[i].is_live()      ? true : false;

   321     assert(v3 == v4, "locals live mask generation error");

   322     assert(!(v1 && v3), "dead value marked as oop");

   323 #endif

   324   }

   325 

   326   if (TraceOopMapGeneration && Verbose) { tty->cr(); tty->print("Stack (%d): ", stack_top); }

   327   for(int j = 0; j < stack_top; j++) {

   328     bool v1 = is_oop(max_locals + j)  ? true : false;

   329     bool v2 = stack[j].is_reference() ? true : false;

   330     assert(v1 == v2, "stack oop mask generation error");

   331     if (TraceOopMapGeneration && Verbose) tty->print("%d", v1 ? 1 : 0);

   332 #ifdef ENABLE_ZAP_DEAD_LOCALS

   333     bool v3 = is_dead(max_locals + j) ? true : false;

   334     bool v4 = !stack[j].is_live()     ? true : false;

   335     assert(v3 == v4, "stack live mask generation error");

   336     assert(!(v1 && v3), "dead value marked as oop");

   337 #endif

   338   }

   339   if (TraceOopMapGeneration && Verbose) tty->cr();

   340   return true;

   341 }

   342 

   343 void OopMapCacheEntry::allocate_bit_mask() {

   344   if (mask_size() > small_mask_limit) {

   345     assert(_bit_mask[0] == 0, "bit mask should be new or just flushed");

   346     _bit_mask[0] = (intptr_t)

   347       NEW_C_HEAP_ARRAY(uintptr_t, mask_word_size());

   348   }

   349 }

   350 

   351 void OopMapCacheEntry::deallocate_bit_mask() {

   352   if (mask_size() > small_mask_limit && _bit_mask[0] != 0) {

   353     assert(!Thread::current()->resource_area()->contains((void*)_bit_mask[0]),

   354       "This bit mask should not be in the resource area");

   355     FREE_C_HEAP_ARRAY(uintptr_t, _bit_mask[0]);

   356     debug_only(_bit_mask[0] = 0;)

   357   }

   358 }

   359 

   360 

   361 void OopMapCacheEntry::fill_for_native(methodHandle mh) {

   362   assert(mh->is_native(), "method must be native method");

   363   set_mask_size(mh->size_of_parameters() * bits_per_entry);

   364   allocate_bit_mask();

   365   // fill mask for parameters

   366   MaskFillerForNative mf(mh, bit_mask(), mask_size());

   367   mf.generate();

   368 }

   369 

   370 

   371 void OopMapCacheEntry::fill(methodHandle method, int bci) {

   372   HandleMark hm;

   373   // Flush entry to deallocate an existing entry

   374   flush();

   375   set_method(method());

   376   set_bci(bci);

   377   if (method->is_native()) {

   378     // Native method activations have oops only among the parameters and one

   379     // extra oop following the parameters (the mirror for static native methods).

   380     fill_for_native(method);

   381   } else {

   382     EXCEPTION_MARK;

   383     OopMapForCacheEntry gen(method, bci, this);

   384     gen.compute_map(CATCH);

   385   }

   386   #ifdef ASSERT

   387     verify();

   388   #endif

   389 }

   390 

   391 

   392 void OopMapCacheEntry::set_mask(CellTypeState *vars, CellTypeState *stack, int stack_top) {

   393   // compute bit mask size

   394   int max_locals = method()->max_locals();

   395   int n_entries = max_locals + stack_top;

   396   set_mask_size(n_entries * bits_per_entry);

   397   allocate_bit_mask();

   398   set_expression_stack_size(stack_top);

   399 

   400   // compute bits

   401   int word_index = 0;

   402   uintptr_t value = 0;

   403   uintptr_t mask = 1;

   404 

   405   CellTypeState* cell = vars;

   406   for (int entry_index = 0; entry_index < n_entries; entry_index++, mask <<= bits_per_entry, cell++) {

   407     // store last word

   408     if (mask == 0) {

   409       bit_mask()[word_index++] = value;

   410       value = 0;

   411       mask = 1;

   412     }

   413 

   414     // switch to stack when done with locals

   415     if (entry_index == max_locals) {

   416       cell = stack;

   417     }

   418 

   419     // set oop bit

   420     if ( cell->is_reference()) {

   421       value |= (mask << oop_bit_number );

   422     }

   423 

   424   #ifdef ENABLE_ZAP_DEAD_LOCALS

   425     // set dead bit

   426     if (!cell->is_live()) {

   427       value |= (mask << dead_bit_number);

   428       assert(!cell->is_reference(), "dead value marked as oop");

   429     }

   430   #endif

   431   }

   432 

   433   // make sure last word is stored

   434   bit_mask()[word_index] = value;

   435 

   436   // verify bit mask

   437   assert(verify_mask(vars, stack, max_locals, stack_top), "mask could not be verified");

   438 

   439 

   440 }

   441 

   442 void OopMapCacheEntry::flush() {

   443   deallocate_bit_mask();

   444   initialize();

   445 }

   446 

   447 

   448 // Implementation of OopMapCache

   449 

   450 #ifndef PRODUCT

   451 

   452 static long _total_memory_usage = 0;

   453 

   454 long OopMapCache::memory_usage() {

   455   return _total_memory_usage;

   456 }

   457 

   458 #endif

   459 

   460 void InterpreterOopMap::resource_copy(OopMapCacheEntry* from) {

   461   assert(_resource_allocate_bit_mask,

   462     "Should not resource allocate the _bit_mask");

   463   assert(from->method()->is_oop(), "MethodOop is bad");

   464 

   465   set_method(from->method());

   466   set_bci(from->bci());

   467   set_mask_size(from->mask_size());

   468   set_expression_stack_size(from->expression_stack_size());

   469 

   470   // Is the bit mask contained in the entry?

   471   if (from->mask_size() <= small_mask_limit) {

   472     memcpy((void *)_bit_mask, (void *)from->_bit_mask,

   473       mask_word_size() * BytesPerWord);

   474   } else {

   475     // The expectation is that this InterpreterOopMap is a recently created

   476     // and empty. It is used to get a copy of a cached entry.

   477     // If the bit mask has a value, it should be in the

   478     // resource area.

   479     assert(_bit_mask[0] == 0 ||

   480       Thread::current()->resource_area()->contains((void*)_bit_mask[0]),

   481       "The bit mask should have been allocated from a resource area");

   482     // Allocate the bit_mask from a Resource area for performance.  Allocating

   483     // from the C heap as is done for OopMapCache has a significant

   484     // performance impact.

   485     _bit_mask[0] = (uintptr_t) NEW_RESOURCE_ARRAY(uintptr_t, mask_word_size());

   486     assert(_bit_mask[0] != 0, "bit mask was not allocated");

   487     memcpy((void*) _bit_mask[0], (void*) from->_bit_mask[0],

   488       mask_word_size() * BytesPerWord);

   489   }

   490 }

   491 

   492 inline unsigned int OopMapCache::hash_value_for(methodHandle method, int bci) {

   493   // We use method->code_size() rather than method->identity_hash() below since

   494   // the mark may not be present if a pointer to the method is already reversed.

   495   return   ((unsigned int) bci)

   496          ^ ((unsigned int) method->max_locals()         << 2)

   497          ^ ((unsigned int) method->code_size()          << 4)

   498          ^ ((unsigned int) method->size_of_parameters() << 6);

   499 }

   500 

   501 

   502 OopMapCache::OopMapCache() :

   503   _mut(Mutex::leaf, "An OopMapCache lock", true)

   504 {

   505   _array  = NEW_C_HEAP_ARRAY(OopMapCacheEntry, _size);

   506   // Cannot call flush for initialization, since flush

   507   // will check if memory should be deallocated

   508   for(int i = 0; i < _size; i++) _array[i].initialize();

   509   NOT_PRODUCT(_total_memory_usage += sizeof(OopMapCache) + (sizeof(OopMapCacheEntry) * _size);)

   510 }

   511 

   512 

   513 OopMapCache::~OopMapCache() {

   514   assert(_array != NULL, "sanity check");

   515   // Deallocate oop maps that are allocated out-of-line

   516   flush();

   517   // Deallocate array

   518   NOT_PRODUCT(_total_memory_usage -= sizeof(OopMapCache) + (sizeof(OopMapCacheEntry) * _size);)

   519   FREE_C_HEAP_ARRAY(OopMapCacheEntry, _array);

   520 }

   521 

   522 OopMapCacheEntry* OopMapCache::entry_at(int i) const {

   523   return &_array[i % _size];

   524 }

   525 

   526 void OopMapCache::flush() {

   527   for (int i = 0; i < _size; i++) _array[i].flush();

   528 }

   529 

   530 void OopMapCache::flush_obsolete_entries() {

   531   for (int i = 0; i < _size; i++)

   532     if (!_array[i].is_empty() && _array[i].method()->is_old()) {

   533       // Cache entry is occupied by an old redefined method and we don't want

   534       // to pin it down so flush the entry.

   535       _array[i].flush();

   536     }

   537 }

   538 

   539 void OopMapCache::oop_iterate(OopClosure *blk) {

   540   for (int i = 0; i < _size; i++) _array[i].oop_iterate(blk);

   541 }

   542 

   543 void OopMapCache::oop_iterate(OopClosure *blk, MemRegion mr) {

   544     for (int i = 0; i < _size; i++) _array[i].oop_iterate(blk, mr);

   545 }

   546 

   547 void OopMapCache::verify() {

   548   for (int i = 0; i < _size; i++) _array[i].verify();

   549 }

   550 

   551 void OopMapCache::lookup(methodHandle method,

   552                          int bci,

   553                          InterpreterOopMap* entry_for) {

   554   MutexLocker x(&_mut);

   555 

   556   OopMapCacheEntry* entry = NULL;

   557   int probe = hash_value_for(method, bci);

   558 

   559   // Search hashtable for match

   560   int i;

   561   for(i = 0; i < _probe_depth; i++) {

   562     entry = entry_at(probe + i);

   563     if (entry->match(method, bci)) {

   564       entry_for->resource_copy(entry);

   565       assert(!entry_for->is_empty(), "A non-empty oop map should be returned");

   566       return;

   567     }

   568   }

   569 

   570   if (TraceOopMapGeneration) {

   571     static int count = 0;

   572     ResourceMark rm;

   573     tty->print("%d - Computing oopmap at bci %d for ", ++count, bci);

   574     method->print_value(); tty->cr();

   575   }

   576 

   577   // Entry is not in hashtable.

   578   // Compute entry and return it

   579 

   580   // First search for an empty slot

   581   for(i = 0; i < _probe_depth; i++) {

   582     entry  = entry_at(probe + i);

   583     if (entry->is_empty()) {

   584       entry->fill(method, bci);

   585       entry_for->resource_copy(entry);

   586       assert(!entry_for->is_empty(), "A non-empty oop map should be returned");

   587       if (method->is_old()) {

   588         // The caller of lookup() will receive a copy of the interesting

   589         // info via entry_for, but we don't keep an old redefined method in

   590         // the cache to avoid pinning down the method.

   591         entry->flush();

   592       }

   593       return;

   594     }

   595   }

   596 

   597   if (TraceOopMapGeneration) {

   598     ResourceMark rm;

   599     tty->print_cr("*** collision in oopmap cache - flushing item ***");

   600   }

   601 

   602   // No empty slot (uncommon case). Use (some approximation of a) LRU algorithm

   603   //entry_at(probe + _probe_depth - 1)->flush();

   604   //for(i = _probe_depth - 1; i > 0; i--) {

   605   //  // Coping entry[i] = entry[i-1];

   606   //  OopMapCacheEntry *to   = entry_at(probe + i);

   607   //  OopMapCacheEntry *from = entry_at(probe + i - 1);

   608   //  to->copy(from);

   609   // }

   610 

   611   assert(method->is_method(), "gaga");

   612 

   613   entry = entry_at(probe + 0);

   614   entry->fill(method, bci);

   615 

   616   // Copy the  newly cached entry to input parameter

   617   entry_for->resource_copy(entry);

   618 

   619   if (TraceOopMapGeneration) {

   620     ResourceMark rm;

   621     tty->print("Done with ");

   622     method->print_value(); tty->cr();

   623   }

   624   assert(!entry_for->is_empty(), "A non-empty oop map should be returned");

   625 

   626   if (method->is_old()) {

   627     // The caller of lookup() will receive a copy of the interesting

   628     // info via entry_for, but we don't keep an old redefined method in

   629     // the cache to avoid pinning down the method.

   630     entry->flush();

   631   }

   632 

   633   return;

   634 }

   635 

   636 void OopMapCache::compute_one_oop_map(methodHandle method, int bci, InterpreterOopMap* entry) {

   637   // Due to the invariants above it's tricky to allocate a temporary OopMapCacheEntry on the stack

   638   OopMapCacheEntry* tmp = NEW_C_HEAP_ARRAY(OopMapCacheEntry, 1);

   639   tmp->initialize();

   640   tmp->fill(method, bci);

   641   entry->resource_copy(tmp);

   642   FREE_C_HEAP_ARRAY(OopMapCacheEntry, tmp);

   643 }