1 /*
   2  * Copyright (c) 1997, 2019, 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_OOPS_OOPSHIERARCHY_HPP
  26 #define SHARE_OOPS_OOPSHIERARCHY_HPP
  27 
  28 #include "metaprogramming/integralConstant.hpp"
  29 #include "metaprogramming/primitiveConversions.hpp"
  30 #include "utilities/globalDefinitions.hpp"
  31 
  32 // OBJECT hierarchy
  33 // This hierarchy is a representation hierarchy, i.e. if A is a superclass
  34 // of B, A's representation is a prefix of B's representation.
  35 
  36 typedef juint narrowOop; // Offset instead of address for an oop within a java object
  37 
  38 // If compressed klass pointers then use narrowKlass.
  39 typedef juint  narrowKlass;
  40 
  41 typedef void* OopOrNarrowOopStar;
  42 typedef class   markOopDesc*                markOop;
  43 
  44 #ifndef CHECK_UNHANDLED_OOPS
  45 
  46 typedef class oopDesc*                            oop;
  47 typedef class   instanceOopDesc*            instanceOop;
  48 typedef class   arrayOopDesc*                    arrayOop;
  49 typedef class     objArrayOopDesc*            objArrayOop;
  50 typedef class     typeArrayOopDesc*            typeArrayOop;
  51 
  52 #else
  53 
  54 // When CHECK_UNHANDLED_OOPS is defined, an "oop" is a class with a
  55 // carefully chosen set of constructors and conversion operators to go
  56 // to and from the underlying oopDesc pointer type.
  57 //
  58 // Because oop and its subclasses <type>Oop are class types, arbitrary
  59 // conversions are not accepted by the compiler.  Applying a cast to
  60 // an oop will cause the best matched conversion operator to be
  61 // invoked returning the underlying oopDesc* type if appropriate.
  62 // No copy constructors, explicit user conversions or operators of
  63 // numerical type should be defined within the oop class. Most C++
  64 // compilers will issue a compile time error concerning the overloading
  65 // ambiguity between operators of numerical and pointer types. If
  66 // a conversion to or from an oop to a numerical type is needed,
  67 // use the inline template methods, cast_*_oop, defined below.
  68 //
  69 // Converting NULL to oop to Handle implicit is no longer accepted by the
  70 // compiler because there are too many steps in the conversion.  Use Handle()
  71 // instead, which generates less code anyway.
  72 
  73 class Thread;
  74 class PromotedObject;
  75 class oopDesc;
  76 
  77 extern bool CheckUnhandledOops;
  78 
  79 class oop {
  80   oopDesc* _o;
  81 
  82   void register_oop();
  83   void unregister_oop();
  84 
  85   // friend class markOop;
  86 public:
  87   void set_obj(const void* p)         {
  88     raw_set_obj(p);
  89     if (CheckUnhandledOops) register_oop();
  90   }
  91   void raw_set_obj(const void* p)     { _o = (oopDesc*)p; }
  92 
  93   oop()                               { set_obj(NULL); }
  94   oop(const oop& o)                   { set_obj(o.obj()); }
  95   oop(const volatile oop& o)          { set_obj(o.obj()); }
  96   oop(const void* p)                  { set_obj(p); }
  97   ~oop()                              {
  98     if (CheckUnhandledOops) unregister_oop();
  99   }
 100 
 101   oopDesc* obj()  const volatile      { return _o; }
 102 
 103   // General access
 104   oopDesc*  operator->() const        { return obj(); }
 105   bool operator==(const oop o) const;
 106   bool operator==(void *p) const      { return obj() == p; }
 107   bool operator!=(const volatile oop o) const;
 108   bool operator!=(void *p) const      { return obj() != p; }
 109 
 110   // Assignment
 111   oop& operator=(const oop& o)                            { _o = o.obj(); return *this; }
 112   volatile oop& operator=(const oop& o) volatile          { _o = o.obj(); return *this; }
 113   volatile oop& operator=(const volatile oop& o) volatile { _o = o.obj(); return *this; }
 114 
 115   // Explict user conversions
 116   operator void* () const             { return (void *)obj(); }
 117 #ifndef SOLARIS
 118   operator void* () const volatile    { return (void *)obj(); }
 119 #endif
 120   operator HeapWord* () const         { return (HeapWord*)obj(); }
 121   operator oopDesc* () const volatile { return obj(); }
 122   operator intptr_t* () const         { return (intptr_t*)obj(); }
 123   operator PromotedObject* () const   { return (PromotedObject*)obj(); }
 124   operator markOop () const volatile  { return markOop(obj()); }
 125   operator address   () const         { return (address)obj(); }
 126 
 127   // from javaCalls.cpp
 128   operator jobject () const           { return (jobject)obj(); }
 129 
 130   // from parNewGeneration and other things that want to get to the end of
 131   // an oop for stuff (like ObjArrayKlass.cpp)
 132   operator oop* () const              { return (oop *)obj(); }
 133 };
 134 
 135 template<>
 136 struct PrimitiveConversions::Translate<oop> : public TrueType {
 137   typedef oop Value;
 138   typedef oopDesc* Decayed;
 139 
 140   static Decayed decay(Value x) { return x.obj(); }
 141   static Value recover(Decayed x) { return oop(x); }
 142 };
 143 
 144 #define DEF_OOP(type)                                                      \
 145    class type##OopDesc;                                                    \
 146    class type##Oop : public oop {                                          \
 147      public:                                                               \
 148        type##Oop() : oop() {}                                              \
 149        type##Oop(const oop& o) : oop(o) {}                                 \
 150        type##Oop(const volatile oop& o) : oop(o) {}                        \
 151        type##Oop(const void* p) : oop(p) {}                                \
 152        operator type##OopDesc* () const { return (type##OopDesc*)obj(); }  \
 153        type##OopDesc* operator->() const {                                 \
 154             return (type##OopDesc*)obj();                                  \
 155        }                                                                   \
 156        type##Oop& operator=(const type##Oop& o) {                          \
 157             oop::operator=(o);                                             \
 158             return *this;                                                  \
 159        }                                                                   \
 160        volatile type##Oop& operator=(const type##Oop& o) volatile {        \
 161             (void)const_cast<oop&>(oop::operator=(o));                     \
 162             return *this;                                                  \
 163        }                                                                   \
 164        volatile type##Oop& operator=(const volatile type##Oop& o) volatile {\
 165             (void)const_cast<oop&>(oop::operator=(o));                     \
 166             return *this;                                                  \
 167        }                                                                   \
 168    };                                                                      \
 169                                                                            \
 170    template<>                                                              \
 171    struct PrimitiveConversions::Translate<type##Oop> : public TrueType {   \
 172      typedef type##Oop Value;                                              \
 173      typedef type##OopDesc* Decayed;                                       \
 174                                                                            \
 175      static Decayed decay(Value x) { return (type##OopDesc*)x.obj(); }     \
 176      static Value recover(Decayed x) { return type##Oop(x); }              \
 177    };
 178 
 179 DEF_OOP(instance);
 180 DEF_OOP(array);
 181 DEF_OOP(objArray);
 182 DEF_OOP(typeArray);
 183 
 184 #endif // CHECK_UNHANDLED_OOPS
 185 
 186 // For CHECK_UNHANDLED_OOPS, it is ambiguous C++ behavior to have the oop
 187 // structure contain explicit user defined conversions of both numerical
 188 // and pointer type. Define inline methods to provide the numerical conversions.
 189 template <class T> inline oop cast_to_oop(T value) {
 190   return (oop)(CHECK_UNHANDLED_OOPS_ONLY((void *))(value));
 191 }
 192 template <class T> inline T cast_from_oop(oop o) {
 193   return (T)(CHECK_UNHANDLED_OOPS_ONLY((void*))o);
 194 }
 195 
 196 inline bool check_obj_alignment(oop obj) {
 197   return (cast_from_oop<intptr_t>(obj) & MinObjAlignmentInBytesMask) == 0;
 198 }
 199 
 200 // The metadata hierarchy is separate from the oop hierarchy
 201 
 202 //      class MetaspaceObj
 203 class   ConstMethod;
 204 class   ConstantPoolCache;
 205 class   MethodData;
 206 //      class Metadata
 207 class   Method;
 208 class   ConstantPool;
 209 //      class CHeapObj
 210 class   CompiledICHolder;
 211 
 212 
 213 // The klass hierarchy is separate from the oop hierarchy.
 214 
 215 class Klass;
 216 class   InstanceKlass;
 217 class     InstanceMirrorKlass;
 218 class     InstanceClassLoaderKlass;
 219 class     InstanceRefKlass;
 220 class   ArrayKlass;
 221 class     ObjArrayKlass;
 222 class     TypeArrayKlass;
 223 
 224 #endif // SHARE_OOPS_OOPSHIERARCHY_HPP