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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7 * published by the Free Software Foundation.
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23 */
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 typedef class flatArrayOopDesc* flatArrayOop;
51 typedef class refArrayOopDesc* refArrayOop;
52
53 #else
54
55 // When CHECK_UNHANDLED_OOPS is defined, an "oop" is a class with a
56 // carefully chosen set of constructors and conversion operators to go
57 // to and from the underlying oopDesc pointer type.
58 //
59 // Because oop and its subclasses <type>Oop are class types, arbitrary
60 // conversions are not accepted by the compiler. Applying a cast to
61 // an oop will cause the best matched conversion operator to be
62 // invoked returning the underlying oopDesc* type if appropriate.
63 // No copy constructors, explicit user conversions or operators of
64 // numerical type should be defined within the oop class. Most C++
65 // compilers will issue a compile time error concerning the overloading
66 // ambiguity between operators of numerical and pointer types. If
67 // a conversion to or from an oop to a numerical type is needed,
68 // use the inline template methods, cast_*_oop, defined below.
69 //
70 // Converting null to oop to Handle implicit is no longer accepted by the
71 // compiler because there are too many steps in the conversion. Use Handle()
72 // instead, which generates less code anyway.
73
74 class Thread;
75 class oopDesc;
76
77 extern "C" bool CheckUnhandledOops;
78
79 // Extra verification when creating and using oops.
80 // Used to catch broken oops as soon as possible.
81 using CheckOopFunctionPointer = void(*)(oopDesc*);
82 extern CheckOopFunctionPointer check_oop_function;
83
84 class oop {
85 oopDesc* _o;
86
87 void register_oop();
88 void unregister_oop();
89
90 // Extra verification of the oop
91 void check_oop() const { if (check_oop_function != nullptr && _o != nullptr) check_oop_function(_o); }
92
93 void on_usage() const { check_oop(); }
94 void on_construction() { check_oop(); if (CheckUnhandledOops) register_oop(); }
95 void on_destruction() { if (CheckUnhandledOops) unregister_oop(); }
96
97 public:
98 oop() : _o(nullptr) { on_construction(); }
99 oop(const oop& o) : _o(o._o) { on_construction(); }
100 oop(oopDesc* o) : _o(o) { on_construction(); }
101 ~oop() {
102 on_destruction();
103 }
104
105 oopDesc* obj() const { on_usage(); return _o; }
106
107 oopDesc* operator->() const { return obj(); }
108 operator oopDesc* () const { return obj(); }
109
110 bool operator==(const oop& o) const { return obj() == o.obj(); }
111 bool operator!=(const oop& o) const { return obj() != o.obj(); }
112
113 bool operator==(std::nullptr_t) const { return obj() == nullptr; }
114 bool operator!=(std::nullptr_t) const { return obj() != nullptr; }
115
116 oop& operator=(const oop& o) { _o = o.obj(); return *this; }
117 };
118
119 template<>
120 struct PrimitiveConversions::Translate<oop> : public std::true_type {
121 typedef oop Value;
122 typedef oopDesc* Decayed;
123
124 static Decayed decay(Value x) { return x.obj(); }
125 static Value recover(Decayed x) { return oop(x); }
126 };
127
128 #define DEF_OOP(type) \
129 class type##OopDesc; \
130 class type##Oop : public oop { \
131 public: \
132 type##Oop() : oop() {} \
133 type##Oop(const type##Oop& o) : oop(o) {} \
134 type##Oop(const oop& o) : oop(o) {} \
135 type##Oop(type##OopDesc* o) : oop((oopDesc*)o) {} \
136 operator type##OopDesc* () const { return (type##OopDesc*)obj(); } \
137 type##OopDesc* operator->() const { \
138 return (type##OopDesc*)obj(); \
139 } \
140 type##Oop& operator=(const type##Oop& o) { \
141 oop::operator=(o); \
142 return *this; \
143 } \
144 }; \
145 \
146 template<> \
147 struct PrimitiveConversions::Translate<type##Oop> : public std::true_type { \
148 typedef type##Oop Value; \
149 typedef type##OopDesc* Decayed; \
150 \
151 static Decayed decay(Value x) { return (type##OopDesc*)x.obj(); } \
152 static Value recover(Decayed x) { return type##Oop(x); } \
153 };
154
155 DEF_OOP(instance);
156 DEF_OOP(stackChunk);
157 DEF_OOP(array);
158 DEF_OOP(objArray);
159 DEF_OOP(typeArray);
160 DEF_OOP(flatArray);
161 DEF_OOP(refArray);
162
163 #endif // CHECK_UNHANDLED_OOPS
164
165 // Cast functions to convert to and from oops.
166 template <typename T> inline oop cast_to_oop(T value) {
167 return (oopDesc*)value;
168 }
169 template <typename T> inline T cast_from_oop(oop o) {
170 return (T)(CHECK_UNHANDLED_OOPS_ONLY((oopDesc*))o);
171 }
172
173 inline intptr_t p2i(narrowOop o) {
174 return static_cast<intptr_t>(o);
175 }
176
177 // The metadata hierarchy is separate from the oop hierarchy
178
179 // class MetaspaceObj
180 class ConstMethod;
181 class ConstantPoolCache;
182 class MethodData;
183 // class Metadata
184 class Method;
185 class ConstantPool;
186
187 // The klass hierarchy is separate from the oop hierarchy.
188
189 class Klass;
190 class InstanceKlass;
191 class InlineKlass;
192 class InstanceMirrorKlass;
193 class InstanceClassLoaderKlass;
194 class InstanceRefKlass;
195 class InstanceStackChunkKlass;
196 class ArrayKlass;
197 class ObjArrayKlass;
198 class TypeArrayKlass;
199 class FlatArrayKlass;
200
201 #endif // SHARE_OOPS_OOPSHIERARCHY_HPP