1 /*
   2  * Copyright (c) 1997, 2014, 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_OOPSHIERARCHY_HPP
  26 #define SHARE_VM_OOPS_OOPSHIERARCHY_HPP
  27 
  28 #include "runtime/globals.hpp"
  29 #include "utilities/globalDefinitions.hpp"
  30 
  31 // OBJECT hierarchy
  32 // This hierarchy is a representation hierarchy, i.e. if A is a superclass
  33 // of B, A's representation is a prefix of B's representation.
  34 
  35 typedef juint narrowOop; // Offset instead of address for an oop within a java object
  36 
  37 // If compressed klass pointers then use narrowKlass.
  38 typedef juint  narrowKlass;
  39 
  40 typedef void* OopOrNarrowOopStar;
  41 typedef class   markOopDesc*                markOop;
  42 
  43 #ifndef CHECK_UNHANDLED_OOPS
  44 
  45 typedef class oopDesc*                            oop;
  46 typedef class   instanceOopDesc*            instanceOop;
  47 typedef class   arrayOopDesc*                    arrayOop;
  48 typedef class     objArrayOopDesc*            objArrayOop;
  49 typedef class     typeArrayOopDesc*            typeArrayOop;
  50 
  51 #else
  52 
  53 // When CHECK_UNHANDLED_OOPS is defined, an "oop" is a class with a
  54 // carefully chosen set of constructors and conversion operators to go
  55 // to and from the underlying oopDesc pointer type.
  56 //
  57 // Because oop and its subclasses <type>Oop are class types, arbitrary
  58 // conversions are not accepted by the compiler.  Applying a cast to
  59 // an oop will cause the best matched conversion operator to be
  60 // invoked returning the underlying oopDesc* type if appropriate.
  61 // No copy constructors, explicit user conversions or operators of
  62 // numerical type should be defined within the oop class. Most C++
  63 // compilers will issue a compile time error concerning the overloading
  64 // ambiguity between operators of numerical and pointer types. If
  65 // a conversion to or from an oop to a numerical type is needed,
  66 // use the inline template methods, cast_*_oop, defined below.
  67 //
  68 // Converting NULL to oop to Handle implicit is no longer accepted by the
  69 // compiler because there are too many steps in the conversion.  Use Handle()
  70 // instead, which generates less code anyway.
  71 
  72 class Thread;
  73 class PromotedObject;
  74 
  75 
  76 class oop {
  77   oopDesc* _o;
  78 
  79   void register_oop();
  80   void unregister_oop();
  81 
  82   // friend class markOop;
  83 public:
  84   void set_obj(const void* p)         {
  85     raw_set_obj(p);
  86     if (CheckUnhandledOops) register_oop();
  87   }
  88   void raw_set_obj(const void* p)     { _o = (oopDesc*)p; }
  89 
  90   oop()                               { set_obj(NULL); }
  91   oop(const oop& o)                   { set_obj(o.obj()); }
  92   oop(const volatile oop& o)          { set_obj(o.obj()); }
  93   oop(const void* p)                  { set_obj(p); }
  94   ~oop()                              {
  95     if (CheckUnhandledOops) unregister_oop();
  96   }
  97 
  98   oopDesc* obj()  const volatile      { return _o; }
  99 
 100   // General access
 101   oopDesc*  operator->() const        { return obj(); }
 102   bool operator==(const oop o) const  { return obj() == o.obj(); }
 103   bool operator==(void *p) const      { return obj() == p; }
 104   bool operator!=(const volatile oop o) const  { return obj() != o.obj(); }
 105   bool operator!=(void *p) const      { return obj() != p; }
 106 
 107   bool operator<(oop o) const         { return obj() < o.obj(); }
 108   bool operator>(oop o) const         { return obj() > o.obj(); }
 109   bool operator<=(oop o) const        { return obj() <= o.obj(); }
 110   bool operator>=(oop o) const        { return obj() >= o.obj(); }
 111   bool operator!() const              { return !obj(); }
 112 
 113   // Assignment
 114   oop& operator=(const oop& o)                            { _o = o.obj(); return *this; }
 115   volatile oop& operator=(const oop& o) volatile          { _o = o.obj(); return *this; }
 116   volatile oop& operator=(const volatile oop& o) volatile { _o = o.obj(); return *this; }
 117 
 118   // Explict user conversions
 119   operator void* () const             { return (void *)obj(); }
 120 #ifndef SOLARIS
 121   operator void* () const volatile    { return (void *)obj(); }
 122 #endif
 123   operator HeapWord* () const         { return (HeapWord*)obj(); }
 124   operator oopDesc* () const volatile { return obj(); }
 125   operator intptr_t* () const         { return (intptr_t*)obj(); }
 126   operator PromotedObject* () const   { return (PromotedObject*)obj(); }
 127   operator markOop () const           { return markOop(obj()); }
 128   operator address   () const         { return (address)obj(); }
 129 
 130   // from javaCalls.cpp
 131   operator jobject () const           { return (jobject)obj(); }
 132   // from javaClasses.cpp
 133   operator JavaThread* () const       { return (JavaThread*)obj(); }
 134 
 135 #ifndef _LP64
 136   // from jvm.cpp
 137   operator jlong* () const            { return (jlong*)obj(); }
 138 #endif
 139 
 140   // from parNewGeneration and other things that want to get to the end of
 141   // an oop for stuff (like ObjArrayKlass.cpp)
 142   operator oop* () const              { return (oop *)obj(); }
 143 };
 144 
 145 #define DEF_OOP(type)                                                      \
 146    class type##OopDesc;                                                    \
 147    class type##Oop : public oop {                                          \
 148      public:                                                               \
 149        type##Oop() : oop() {}                                              \
 150        type##Oop(const oop& o) : oop(o) {}                                 \
 151        type##Oop(const volatile oop& o) : oop(o) {}                        \
 152        type##Oop(const void* p) : oop(p) {}                                \
 153        operator type##OopDesc* () const { return (type##OopDesc*)obj(); }  \
 154        type##OopDesc* operator->() const {                                 \
 155             return (type##OopDesc*)obj();                                  \
 156        }                                                                   \
 157        type##Oop& operator=(const type##Oop& o) {                          \
 158             oop::operator=(o);                                             \
 159             return *this;                                                  \
 160        }                                                                   \
 161        volatile type##Oop& operator=(const type##Oop& o) volatile {        \
 162             (void)const_cast<oop&>(oop::operator=(o));                     \
 163             return *this;                                                  \
 164        }                                                                   \
 165        volatile type##Oop& operator=(const volatile type##Oop& o) volatile {\
 166             (void)const_cast<oop&>(oop::operator=(o));                     \
 167             return *this;                                                  \
 168        }                                                                   \
 169    };
 170 
 171 DEF_OOP(instance);
 172 DEF_OOP(array);
 173 DEF_OOP(objArray);
 174 DEF_OOP(typeArray);
 175 
 176 #endif // CHECK_UNHANDLED_OOPS
 177 
 178 // For CHECK_UNHANDLED_OOPS, it is ambiguous C++ behavior to have the oop
 179 // structure contain explicit user defined conversions of both numerical
 180 // and pointer type. Define inline methods to provide the numerical conversions.
 181 template <class T> inline oop cast_to_oop(T value) {
 182   return (oop)(CHECK_UNHANDLED_OOPS_ONLY((void *))(value));
 183 }
 184 template <class T> inline T cast_from_oop(oop o) {
 185   return (T)(CHECK_UNHANDLED_OOPS_ONLY((void*))o);
 186 }
 187 
 188 // The metadata hierarchy is separate from the oop hierarchy
 189 
 190 //      class MetaspaceObj
 191 class   ConstMethod;
 192 class   ConstantPoolCache;
 193 class   MethodData;
 194 //      class Metadata
 195 class   Method;
 196 class   ConstantPool;
 197 //      class CHeapObj
 198 class   CompiledICHolder;
 199 
 200 
 201 // The klass hierarchy is separate from the oop hierarchy.
 202 
 203 class Klass;
 204 class   InstanceKlass;
 205 class     InstanceMirrorKlass;
 206 class     InstanceClassLoaderKlass;
 207 class     InstanceRefKlass;
 208 class   ArrayKlass;
 209 class     ObjArrayKlass;
 210 class     TypeArrayKlass;
 211 
 212 #endif // SHARE_VM_OOPS_OOPSHIERARCHY_HPP