1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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24
25 #ifndef SHARE_OOPS_OOPSHIERARCHY_HPP
26 #define SHARE_OOPS_OOPSHIERARCHY_HPP
27
28 #include "metaprogramming/primitiveConversions.hpp"
29 #include "utilities/globalDefinitions.hpp"
30
31 #include <type_traits>
32
33 // OBJECT hierarchy
34 // This hierarchy is a representation hierarchy, i.e. if A is a superclass
35 // of B, A's representation is a prefix of B's representation.
36
37 // Global offset instead of address for an oop within a java object.
38 enum class narrowOop : uint32_t { null = 0 };
39
40 typedef void* OopOrNarrowOopStar;
41
42 #ifndef CHECK_UNHANDLED_OOPS
43
44 typedef class oopDesc* oop;
45 typedef class instanceOopDesc* instanceOop;
46 typedef class stackChunkOopDesc* stackChunkOop;
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 oopDesc;
74
75 extern "C" bool CheckUnhandledOops;
76
77 // Extra verification when creating and using oops.
78 // Used to catch broken oops as soon as possible.
79 using CheckOopFunctionPointer = void(*)(oopDesc*);
80 extern CheckOopFunctionPointer check_oop_function;
81
82 class oop {
83 oopDesc* _o;
84
85 void register_oop();
86 void unregister_oop();
87
88 // Extra verification of the oop
89 void check_oop() const { if (check_oop_function != nullptr && _o != nullptr) check_oop_function(_o); }
90
91 void on_usage() const { check_oop(); }
92 void on_construction() { check_oop(); if (CheckUnhandledOops) register_oop(); }
93 void on_destruction() { if (CheckUnhandledOops) unregister_oop(); }
94
95 public:
96 oop() : _o(nullptr) { on_construction(); }
97 oop(const oop& o) : _o(o._o) { on_construction(); }
98 oop(oopDesc* o) : _o(o) { on_construction(); }
99 ~oop() {
100 on_destruction();
101 }
102
103 oopDesc* obj() const { on_usage(); return _o; }
104
105 oopDesc* operator->() const { return obj(); }
106 operator oopDesc* () const { return obj(); }
107
108 bool operator==(const oop& o) const { return obj() == o.obj(); }
109 bool operator!=(const oop& o) const { return obj() != o.obj(); }
110
111 bool operator==(std::nullptr_t) const { return obj() == nullptr; }
112 bool operator!=(std::nullptr_t) const { return obj() != nullptr; }
113
114 oop& operator=(const oop& o) { _o = o.obj(); return *this; }
115 };
116
117 template<>
118 struct PrimitiveConversions::Translate<oop> : public std::true_type {
119 typedef oop Value;
120 typedef oopDesc* Decayed;
121
122 static Decayed decay(Value x) { return x.obj(); }
123 static Value recover(Decayed x) { return oop(x); }
124 };
125
126 #define DEF_OOP(type) \
127 class type##OopDesc; \
128 class type##Oop : public oop { \
129 public: \
130 type##Oop() : oop() {} \
131 type##Oop(const type##Oop& o) : oop(o) {} \
132 type##Oop(const oop& o) : oop(o) {} \
133 type##Oop(type##OopDesc* o) : oop((oopDesc*)o) {} \
134 operator type##OopDesc* () const { return (type##OopDesc*)obj(); } \
135 type##OopDesc* operator->() const { \
136 return (type##OopDesc*)obj(); \
137 } \
138 type##Oop& operator=(const type##Oop& o) { \
139 oop::operator=(o); \
140 return *this; \
141 } \
142 }; \
143 \
144 template<> \
145 struct PrimitiveConversions::Translate<type##Oop> : public std::true_type { \
146 typedef type##Oop Value; \
147 typedef type##OopDesc* Decayed; \
148 \
149 static Decayed decay(Value x) { return (type##OopDesc*)x.obj(); } \
150 static Value recover(Decayed x) { return type##Oop(x); } \
151 };
152
153 DEF_OOP(instance);
154 DEF_OOP(stackChunk);
155 DEF_OOP(array);
156 DEF_OOP(objArray);
157 DEF_OOP(typeArray);
158
159 #endif // CHECK_UNHANDLED_OOPS
160
161 // Cast functions to convert to and from oops.
162 template <typename T> inline oop cast_to_oop(T value) {
163 return (oopDesc*)value;
164 }
165 template <typename T> inline T cast_from_oop(oop o) {
166 return (T)(CHECK_UNHANDLED_OOPS_ONLY((oopDesc*))o);
167 }
168
169 inline intptr_t p2i(narrowOop o) {
170 return static_cast<intptr_t>(o);
171 }
172
173 // The metadata hierarchy is separate from the oop hierarchy
174
175 // class MetaspaceObj
176 class ConstMethod;
177 class ConstantPoolCache;
178 class MethodData;
179 // class Metadata
180 class Method;
181 class ConstantPool;
182
183 // The klass hierarchy is separate from the oop hierarchy.
184
185 class Klass;
186 class InstanceKlass;
187 class InstanceMirrorKlass;
188 class InstanceClassLoaderKlass;
189 class InstanceRefKlass;
190 class InstanceStackChunkKlass;
191 class ArrayKlass;
192 class ObjArrayKlass;
193 class TypeArrayKlass;
194
195 #endif // SHARE_OOPS_OOPSHIERARCHY_HPP