1 /*
2 * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
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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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).
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23 */
24
25 #ifndef SHARE_VM_OOPS_OOPSHIERARCHY_HPP
26 #define SHARE_VM_OOPS_OOPSHIERARCHY_HPP
27
28 #include "metaprogramming/integralConstant.hpp"
29 #include "metaprogramming/primitiveConversions.hpp"
30 #include "runtime/globals.hpp"
31 #include "utilities/globalDefinitions.hpp"
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 typedef juint narrowOop; // Offset instead of address for an oop within a java object
38
39 // If compressed klass pointers then use narrowKlass.
40 typedef juint narrowKlass;
41
42 typedef void* OopOrNarrowOopStar;
43 typedef class markOopDesc* markOop;
44
45 #ifndef CHECK_UNHANDLED_OOPS
46
47 typedef class oopDesc* oop;
48 typedef class instanceOopDesc* instanceOop;
49 typedef class arrayOopDesc* arrayOop;
50 typedef class objArrayOopDesc* objArrayOop;
51 typedef class typeArrayOopDesc* typeArrayOop;
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 PromotedObject;
76
77
78 class oop {
79 oopDesc* _o;
80
81 void register_oop();
82 void unregister_oop();
83
84 // friend class markOop;
85 public:
86 void set_obj(const void* p) {
87 raw_set_obj(p);
88 if (CheckUnhandledOops) register_oop();
89 }
90 void raw_set_obj(const void* p) { _o = (oopDesc*)p; }
91
92 oop() { set_obj(NULL); }
93 oop(const oop& o) { set_obj(o.obj()); }
94 oop(const volatile oop& o) { set_obj(o.obj()); }
95 oop(const void* p) { set_obj(p); }
96 ~oop() {
97 if (CheckUnhandledOops) unregister_oop();
98 }
99
100 oopDesc* obj() const volatile { return _o; }
101
102 // General access
103 oopDesc* operator->() const { return obj(); }
104 bool operator==(const oop o) const {
105 assert(!VerifyObjectEquals, "Missing oopDesc::equals(..)");
106 return obj() == o.obj();
107 }
108 bool operator==(void *p) const { return obj() == p; }
109 bool operator!=(const volatile oop o) const {
110 assert(!VerifyObjectEquals, "Missing !oopDesc::equals(..)");
111 return obj() != o.obj();
112 }
113 bool operator!=(void *p) const { return obj() != p; }
114
115 // Assignment
116 oop& operator=(const oop& o) { _o = o.obj(); return *this; }
117 volatile oop& operator=(const oop& o) volatile { _o = o.obj(); return *this; }
118 volatile oop& operator=(const volatile oop& o) volatile { _o = o.obj(); return *this; }
119
120 // Explict user conversions
121 operator void* () const { return (void *)obj(); }
122 #ifndef SOLARIS
123 operator void* () const volatile { return (void *)obj(); }
124 #endif
125 operator HeapWord* () const { return (HeapWord*)obj(); }
126 operator oopDesc* () const volatile { return obj(); }
127 operator intptr_t* () const { return (intptr_t*)obj(); }
128 operator PromotedObject* () const { return (PromotedObject*)obj(); }
129 operator markOop () const volatile { return markOop(obj()); }
130 operator address () const { return (address)obj(); }
131
132 // from javaCalls.cpp
133 operator jobject () const { return (jobject)obj(); }
134
135 // from parNewGeneration and other things that want to get to the end of
136 // an oop for stuff (like ObjArrayKlass.cpp)
137 operator oop* () const { return (oop *)obj(); }
138 };
139
140 template<>
141 struct PrimitiveConversions::Translate<oop> : public TrueType {
142 typedef oop Value;
143 typedef oopDesc* Decayed;
144
145 static Decayed decay(Value x) { return x.obj(); }
146 static Value recover(Decayed x) { return oop(x); }
147 };
148
149 #define DEF_OOP(type) \
150 class type##OopDesc; \
151 class type##Oop : public oop { \
152 public: \
153 type##Oop() : oop() {} \
154 type##Oop(const oop& o) : oop(o) {} \
155 type##Oop(const volatile oop& o) : oop(o) {} \
156 type##Oop(const void* p) : oop(p) {} \
157 operator type##OopDesc* () const { return (type##OopDesc*)obj(); } \
158 type##OopDesc* operator->() const { \
159 return (type##OopDesc*)obj(); \
160 } \
161 type##Oop& operator=(const type##Oop& o) { \
162 oop::operator=(o); \
163 return *this; \
164 } \
165 volatile type##Oop& operator=(const type##Oop& o) volatile { \
166 (void)const_cast<oop&>(oop::operator=(o)); \
167 return *this; \
168 } \
169 volatile type##Oop& operator=(const volatile type##Oop& o) volatile {\
170 (void)const_cast<oop&>(oop::operator=(o)); \
171 return *this; \
172 } \
173 }; \
174 \
175 template<> \
176 struct PrimitiveConversions::Translate<type##Oop> : public TrueType { \
177 typedef type##Oop Value; \
178 typedef type##OopDesc* Decayed; \
179 \
180 static Decayed decay(Value x) { return (type##OopDesc*)x.obj(); } \
181 static Value recover(Decayed x) { return type##Oop(x); } \
182 };
183
184 DEF_OOP(instance);
185 DEF_OOP(array);
186 DEF_OOP(objArray);
187 DEF_OOP(typeArray);
188
189 #endif // CHECK_UNHANDLED_OOPS
190
191 // For CHECK_UNHANDLED_OOPS, it is ambiguous C++ behavior to have the oop
192 // structure contain explicit user defined conversions of both numerical
193 // and pointer type. Define inline methods to provide the numerical conversions.
194 template <class T> inline oop cast_to_oop(T value) {
195 return (oop)(CHECK_UNHANDLED_OOPS_ONLY((void *))(value));
196 }
197 template <class T> inline T cast_from_oop(oop o) {
198 return (T)(CHECK_UNHANDLED_OOPS_ONLY((void*))o);
199 }
200
201 inline bool check_obj_alignment(oop obj) {
202 return (cast_from_oop<intptr_t>(obj) & MinObjAlignmentInBytesMask) == 0;
203 }
204
205 // The metadata hierarchy is separate from the oop hierarchy
206
207 // class MetaspaceObj
208 class ConstMethod;
209 class ConstantPoolCache;
210 class MethodData;
211 // class Metadata
212 class Method;
213 class ConstantPool;
214 // class CHeapObj
215 class CompiledICHolder;
216
217
218 // The klass hierarchy is separate from the oop hierarchy.
219
220 class Klass;
221 class InstanceKlass;
222 class InstanceMirrorKlass;
223 class InstanceClassLoaderKlass;
224 class InstanceRefKlass;
225 class ArrayKlass;
226 class ObjArrayKlass;
227 class TypeArrayKlass;
228
229 #endif // SHARE_VM_OOPS_OOPSHIERARCHY_HPP