1 /*

     2  * Copyright (c) 2017, 2018, Red Hat, Inc. All rights reserved.

     3  *

     4  * This code is free software; you can redistribute it and/or modify it

     5  * under the terms of the GNU General Public License version 2 only, as

     6  * published by the Free Software Foundation.

     7  *

     8  * This code is distributed in the hope that it will be useful, but WITHOUT

     9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    11  * version 2 for more details (a copy is included in the LICENSE file that

    12  * accompanied this code).

    13  *

    14  * You should have received a copy of the GNU General Public License version

    15  * 2 along with this work; if not, write to the Free Software Foundation,

    16  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    17  *

    18  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    19  * or visit www.oracle.com if you need additional information or have any

    20  * questions.

    21  *

    22  */

    23 

    24 #ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHCODEROOTS_HPP

    25 #define SHARE_VM_GC_SHENANDOAH_SHENANDOAHCODEROOTS_HPP

    26 

    27 #include "code/codeCache.hpp"

    28 #include "gc/shenandoah/shenandoahSharedVariables.hpp"

    29 #include "memory/allocation.hpp"

    30 #include "memory/iterator.hpp"

    31 

    32 class ShenandoahHeap;

    33 class ShenandoahHeapRegion;

    34 class ShenandoahCodeRootsLock;

    35 

    36 class ShenandoahParallelCodeHeapIterator {

    37   friend class CodeCache;

    38 private:

    39   CodeHeap*     _heap;

    40   DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile int));

    41   volatile int  _claimed_idx;

    42   volatile bool _finished;

    43   DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);

    44 public:

    45   ShenandoahParallelCodeHeapIterator(CodeHeap* heap);

    46   void parallel_blobs_do(CodeBlobClosure* f);

    47 };

    48 

    49 class ShenandoahParallelCodeCacheIterator {

    50   friend class CodeCache;

    51 private:

    52   ShenandoahParallelCodeHeapIterator* _iters;

    53   int                       _length;

    54 public:

    55   ShenandoahParallelCodeCacheIterator(const GrowableArray<CodeHeap*>* heaps);

    56   ~ShenandoahParallelCodeCacheIterator();

    57   void parallel_blobs_do(CodeBlobClosure* f);

    58 };

    59 

    60 // ShenandoahNMethod tuple records the internal locations of oop slots within the nmethod.

    61 // This allows us to quickly scan the oops without doing the nmethod-internal scans, that

    62 // sometimes involves parsing the machine code. Note it does not record the oops themselves,

    63 // because it would then require handling these tuples as the new class of roots.

    64 class ShenandoahNMethod : public CHeapObj<mtGC> {

    65 private:

    66   nmethod* _nm;

    67   oop**    _oops;

    68   int      _oops_count;

    69 

    70 public:

    71   ShenandoahNMethod(nmethod *nm, GrowableArray<oop*>* oops);

    72   ~ShenandoahNMethod();

    73 

    74   nmethod* nm() {

    75     return _nm;

    76   }

    77 

    78   bool has_cset_oops(ShenandoahHeap* heap);

    79 

    80   void assert_alive_and_correct() PRODUCT_RETURN;

    81   void assert_same_oops(GrowableArray<oop*>* oops) PRODUCT_RETURN;

    82 

    83   static bool find_with_nmethod(void* nm, ShenandoahNMethod* other) {

    84     return other->_nm == nm;

    85   }

    86 };

    87 

    88 class ShenandoahCodeRootsIterator {

    89   friend class ShenandoahCodeRoots;

    90 protected:

    91   ShenandoahHeap* _heap;

    92   ShenandoahParallelCodeCacheIterator _par_iterator;

    93   ShenandoahSharedFlag _seq_claimed;

    94   DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile size_t));

    95   volatile size_t _claimed;

    96   DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);

    97 protected:

    98   ShenandoahCodeRootsIterator();

    99   ~ShenandoahCodeRootsIterator();

   100 

   101   template<bool CSET_FILTER>

   102   void dispatch_parallel_blobs_do(CodeBlobClosure *f);

   103 

   104   template<bool CSET_FILTER>

   105   void fast_parallel_blobs_do(CodeBlobClosure *f);

   106 };

   107 

   108 class ShenandoahAllCodeRootsIterator : public ShenandoahCodeRootsIterator {

   109 public:

   110   ShenandoahAllCodeRootsIterator() : ShenandoahCodeRootsIterator() {};

   111   void possibly_parallel_blobs_do(CodeBlobClosure *f);

   112 };

   113 

   114 class ShenandoahCsetCodeRootsIterator : public ShenandoahCodeRootsIterator {

   115 public:

   116   ShenandoahCsetCodeRootsIterator() : ShenandoahCodeRootsIterator() {};

   117   void possibly_parallel_blobs_do(CodeBlobClosure* f);

   118 };

   119 

   120 class ShenandoahCodeRoots : public CHeapObj<mtGC> {

   121   friend class ShenandoahHeap;

   122   friend class ShenandoahCodeRootsLock;

   123   friend class ShenandoahCodeRootsIterator;

   124 

   125 public:

   126   static void initialize();

   127   static void add_nmethod(nmethod* nm);

   128   static void remove_nmethod(nmethod* nm);

   129 

   130   /**

   131    * Provides the iterator over all nmethods in the code cache that have oops.

   132    * @return

   133    */

   134   static ShenandoahAllCodeRootsIterator iterator();

   135 

   136   /**

   137    * Provides the iterator over nmethods that have at least one oop in collection set.

   138    * @return

   139    */

   140   static ShenandoahCsetCodeRootsIterator cset_iterator();

   141 

   142 private:

   143   struct PaddedLock {

   144     DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile int));

   145     volatile int _lock;

   146     DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);

   147   };

   148 

   149   static PaddedLock _recorded_nms_lock;

   150   static GrowableArray<ShenandoahNMethod*>* _recorded_nms;

   151 

   152   static void acquire_lock(bool write) {

   153     volatile int* loc = &_recorded_nms_lock._lock;

   154     if (write) {

   155       while ((OrderAccess::load_acquire(loc) != 0) ||

   156              Atomic::cmpxchg(-1, loc, 0) != 0) {

   157         SpinPause();

   158       }

   159       assert (*loc == -1, "acquired for write");

   160     } else {

   161       while (true) {

   162         int cur = OrderAccess::load_acquire(loc);

   163         if (cur >= 0) {

   164           if (Atomic::cmpxchg(cur + 1, loc, cur) == cur) {

   165             // Success!

   166             assert (*loc > 0, "acquired for read");

   167             return;

   168           }

   169         }

   170         SpinPause();

   171       }

   172     }

   173   }

   174 

   175   static void release_lock(bool write) {

   176     volatile int* loc = &ShenandoahCodeRoots::_recorded_nms_lock._lock;

   177     if (write) {

   178       OrderAccess::release_store_fence(loc, 0);

   179     } else {

   180       Atomic::dec(loc);

   181     }

   182   }

   183 };

   184 

   185 // Very simple unranked read-write lock

   186 class ShenandoahCodeRootsLock : public StackObj {

   187   friend class ShenandoahCodeRoots;

   188 private:

   189   const bool _write;

   190 public:

   191   ShenandoahCodeRootsLock(bool write) : _write(write) {

   192     ShenandoahCodeRoots::acquire_lock(write);

   193   }

   194 

   195   ~ShenandoahCodeRootsLock() {

   196     ShenandoahCodeRoots::release_lock(_write);

   197   }

   198 };

   199 

   200 #endif //SHARE_VM_GC_SHENANDOAH_SHENANDOAHCODEROOTS_HPP