1 /*
   2  * Copyright (c) 1998, 2018, 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 #ifndef SHARE_VM_OOPS_COMPILEDICHOLDEROOP_HPP
  26 #define SHARE_VM_OOPS_COMPILEDICHOLDEROOP_HPP
  27 
  28 #include "oops/oop.hpp"
  29 #include "utilities/macros.hpp"
  30 #include "oops/klass.hpp"
  31 #include "oops/method.hpp"
  32 
  33 // A CompiledICHolder* is a helper object for the inline cache implementation.
  34 // It holds:
  35 //   (1) (method+klass pair) when converting from compiled to an interpreted call
  36 //   (2) (klass+klass pair) when calling itable stub from megamorphic compiled call
  37 //
  38 // These are always allocated in the C heap and are freed during a
  39 // safepoint by the ICBuffer logic.  It's unsafe to free them earlier
  40 // since they might be in use.
  41 //
  42 
  43 
  44 class CompiledICHolder : public CHeapObj<mtCompiler> {
  45   friend class VMStructs;
  46  private:
  47   static volatile int _live_count; // allocated
  48   static volatile int _live_not_claimed_count; // allocated but not yet in use so not
  49                                                // reachable by iterating over nmethods
  50 
  51   Metadata* _holder_metadata;
  52   Klass*    _holder_klass;    // to avoid name conflict with oopDesc::_klass
  53   CompiledICHolder* _next;
  54   bool _is_metadata_method;
  55 
  56  public:
  57   // Constructor
  58   CompiledICHolder(Metadata* metadata, Klass* klass, bool is_method = true);
  59   ~CompiledICHolder() NOT_DEBUG_RETURN;
  60 
  61   static int live_count() { return _live_count; }
  62   static int live_not_claimed_count() { return _live_not_claimed_count; }
  63 
  64   // accessors
  65   Klass*    holder_klass()  const     { return _holder_klass; }
  66   Metadata* holder_metadata() const   { return _holder_metadata; }
  67 
  68   void set_holder_metadata(Metadata* m) { _holder_metadata = m; }
  69   void set_holder_klass(Klass* k)     { _holder_klass = k; }
  70 
  71   static int holder_metadata_offset() { return offset_of(CompiledICHolder, _holder_metadata); }
  72   static int holder_klass_offset()    { return offset_of(CompiledICHolder, _holder_klass); }
  73 
  74   CompiledICHolder* next()     { return _next; }
  75   void set_next(CompiledICHolder* n) { _next = n; }
  76 
  77   inline bool is_loader_alive(BoolObjectClosure* is_alive) {
  78     Klass* k = _is_metadata_method ? ((Method*)_holder_metadata)->method_holder() : (Klass*)_holder_metadata;
  79     if (!k->is_loader_alive(is_alive)) {
  80       return false;
  81     }
  82     if (!_holder_klass->is_loader_alive(is_alive)) {
  83       return false;
  84     }
  85     return true;
  86   }
  87 
  88   // Verify
  89   void verify_on(outputStream* st);
  90 
  91   // Printing
  92   void print_on(outputStream* st) const;
  93   void print_value_on(outputStream* st) const;
  94 
  95   const char* internal_name() const { return "{compiledICHolder}"; }
  96 
  97   void claim() NOT_DEBUG_RETURN;
  98 };
  99 
 100 #endif // SHARE_VM_OOPS_COMPILEDICHOLDEROOP_HPP