1 /*
   2  * Copyright (c) 2011, 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
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  23  */
  24 
  25 #ifndef SHARE_VM_CI_CIBASEOBJECT_HPP
  26 #define SHARE_VM_CI_CIBASEOBJECT_HPP
  27 
  28 #include "ci/ciClassList.hpp"
  29 #include "memory/allocation.hpp"

  30 #include "runtime/jniHandles.hpp"
  31 
  32 // ciBaseObject
  33 //
  34 // This class represents an oop in the HotSpot virtual machine.
  35 // Its subclasses are structured in a hierarchy which mirrors
  36 // an aggregate of the VM's oop and klass hierarchies (see
  37 // oopHierarchy.hpp).  Each instance of ciBaseObject holds a handle
  38 // to a corresponding oop on the VM side and provides routines
  39 // for accessing the information in its oop.  By using the ciBaseObject
  40 // hierarchy for accessing oops in the VM, the compiler ensures
  41 // that it is safe with respect to garbage collection; that is,
  42 // GC and compilation can proceed independently without
  43 // interference.
  44 //
  45 // Within the VM, the oop and klass hierarchies are separate.
  46 // The compiler interface does not preserve this separation --
  47 // the distinction between `Klass*' and `Klass' are not
  48 // reflected in the interface and instead the Klass hierarchy
  49 // is directly modeled as the subclasses of ciKlass.
  50 class ciBaseObject : public ResourceObj {
  51   CI_PACKAGE_ACCESS
  52   friend class ciEnv;
  53 
  54 protected:
  55   uint     _ident;
  56 
  57   enum { FLAG_BITS   = 1 };
  58   enum {
  59          SCAVENGABLE_FLAG = 1
  60        };
  61 protected:
  62   ciBaseObject(): _ident(0) {}
  63 
  64   virtual const char* type_string() { return "ciBaseObject"; }
  65 
  66   void set_ident(uint id);
  67 
  68 public:
  69   // A number unique to this object.
  70   uint ident();
  71 
  72   // What kind of ciBaseObject is this?
  73   virtual bool is_symbol() const       { return false; }
  74   virtual bool is_object() const       { return false; }
  75   virtual bool is_metadata() const     { return false; }
  76 
  77   ciSymbol* as_symbol() {
  78     assert(is_symbol(), "must be");
  79     return (ciSymbol*)this;
  80   }
  81   ciObject* as_object() {
  82     assert(is_object(), "must be");
  83     return (ciObject*)this;
  84   }
  85   ciMetadata* as_metadata() {
  86     assert(is_metadata(), "must be");
  87     return (ciMetadata*)this;
  88   }
  89 };
  90 #endif // SHARE_VM_CI_CIBASEOBJECT_HPP
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