1 /*
   2  * Copyright (c) 1998, 2012, 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 
  31 // A CompiledICHolder* is a helper object for the inline cache implementation.
  32 // It holds:
  33 //   (1) (method+klass pair) when converting from compiled to an interpreted call
  34 //   (2) (klass+klass pair) when calling itable stub from megamorphic compiled call
  35 //
  36 // These are always allocated in the C heap and are freed during a
  37 // safepoint by the ICBuffer logic.  It's unsafe to free them earlier
  38 // since they might be in use.
  39 //
  40 
  41 
  42 class CompiledICHolder : public CHeapObj<mtCompiler> {
  43   friend class VMStructs;
  44  private:
  45   static volatile int _live_count; // allocated
  46   static volatile int _live_not_claimed_count; // allocated but not yet in use so not
  47                                                // reachable by iterating over nmethods
  48 
  49   Metadata* _holder_metadata;
  50   Klass*    _holder_klass;    // to avoid name conflict with oopDesc::_klass
  51   CompiledICHolder* _next;
  52 
  53  public:
  54   // Constructor
  55   CompiledICHolder(Metadata* metadata, Klass* klass);
  56   ~CompiledICHolder() NOT_DEBUG_RETURN;
  57 
  58   static int live_count() { return _live_count; }
  59   static int live_not_claimed_count() { return _live_not_claimed_count; }
  60 
  61   // accessors
  62   Klass*    holder_klass()  const     { return _holder_klass; }
  63   Metadata* holder_metadata() const   { return _holder_metadata; }
  64 
  65   void set_holder_metadata(Metadata* m) { _holder_metadata = m; }
  66   void set_holder_klass(Klass* k)     { _holder_klass = k; }
  67 
  68   static int holder_metadata_offset() { return offset_of(CompiledICHolder, _holder_metadata); }
  69   static int holder_klass_offset()    { return offset_of(CompiledICHolder, _holder_klass); }
  70 
  71   CompiledICHolder* next()     { return _next; }
  72   void set_next(CompiledICHolder* n) { _next = n; }
  73 
  74   bool is_loader_alive(BoolObjectClosure* is_alive);
  75 
  76   // Verify
  77   void verify_on(outputStream* st);
  78 
  79   // Printing
  80   void print_on(outputStream* st) const;
  81   void print_value_on(outputStream* st) const;
  82 
  83   const char* internal_name() const { return "{compiledICHolder}"; }
  84 
  85   void claim() NOT_DEBUG_RETURN;
  86 };
  87 
  88 #endif // SHARE_VM_OOPS_COMPILEDICHOLDEROOP_HPP