1 /*
2 * Copyright (c) 1997, 2021, 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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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,
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24
25 #ifndef SHARE_OOPS_OOP_HPP
26 #define SHARE_OOPS_OOP_HPP
27
28 #include "memory/iterator.hpp"
29 #include "memory/memRegion.hpp"
30 #include "oops/accessDecorators.hpp"
31 #include "oops/compressedKlass.hpp"
32 #include "oops/markWord.hpp"
33 #include "oops/metadata.hpp"
34 #include "runtime/atomic.hpp"
35 #include "utilities/globalDefinitions.hpp"
36 #include "utilities/macros.hpp"
37 #include <type_traits>
38
39 // oopDesc is the top baseclass for objects classes. The {name}Desc classes describe
40 // the format of Java objects so the fields can be accessed from C++.
41 // oopDesc is abstract.
42 // (see oopHierarchy for complete oop class hierarchy)
43 //
44 // no virtual functions allowed
45
46 // Forward declarations.
47 class OopClosure;
48 class FilteringClosure;
49
50 class PSPromotionManager;
51 class ParCompactionManager;
52
53 class oopDesc {
54 friend class VMStructs;
55 friend class JVMCIVMStructs;
56 private:
57 volatile markWord _mark;
58 #ifndef _LP64
59 Klass* _klass;
60 #endif
61
62 // There may be ordering constraints on the initialization of fields that
63 // make use of the C++ copy/assign incorrect.
64 NONCOPYABLE(oopDesc);
65
66 public:
67 // Must be trivial; see verifying static assert after the class.
68 oopDesc() = default;
69
70 inline markWord mark() const;
71 inline markWord mark_acquire() const;
72 inline markWord* mark_addr() const;
73
74 inline void set_mark(markWord m);
75 static inline void set_mark(HeapWord* mem, markWord m);
76
77 inline void release_set_mark(markWord m);
78 static inline void release_set_mark(HeapWord* mem, markWord m);
79 inline markWord cas_set_mark(markWord new_mark, markWord old_mark);
80 inline markWord cas_set_mark(markWord new_mark, markWord old_mark, atomic_memory_order order);
81
82 // Used only to re-initialize the mark word (e.g., of promoted
83 // objects during a GC) -- requires a valid klass pointer
84 inline void init_mark();
85
86 inline Klass* klass() const;
87 inline Klass* klass_or_null() const;
88 inline Klass* klass_or_null_acquire() const;
89
90 #ifndef _LP64
91 inline void set_klass(Klass* k);
92 static inline void release_set_klass(HeapWord* mem, Klass* k);
93 #endif
94
95 // size of object header, aligned to platform wordSize
96 static constexpr int header_size() { return sizeof(oopDesc)/HeapWordSize; }
97
98 // Returns whether this is an instance of k or an instance of a subclass of k
99 inline bool is_a(Klass* k) const;
100
101 // Returns the actual oop size of the object
102 inline size_t size();
103
104 // Sometimes (for complicated concurrency-related reasons), it is useful
105 // to be able to figure out the size of an object knowing its klass.
106 inline size_t size_given_klass(Klass* klass);
107
108 // type test operations (inlined in oop.inline.hpp)
109 inline bool is_instance() const;
110 inline bool is_instanceRef() const;
111 inline bool is_array() const;
112 inline bool is_objArray() const;
113 inline bool is_typeArray() const;
114
115 // type test operations that don't require inclusion of oop.inline.hpp.
116 bool is_instance_noinline() const;
117 bool is_instanceRef_noinline() const;
118 bool is_array_noinline() const;
119 bool is_objArray_noinline() const;
120 bool is_typeArray_noinline() const;
121
122 protected:
123 inline oop as_oop() const { return const_cast<oopDesc*>(this); }
124
125 public:
126 template<typename T>
127 inline T* field_addr(int offset) const;
128
129 template <typename T> inline size_t field_offset(T* p) const;
130
131 // Standard compare function returns negative value if o1 < o2
132 // 0 if o1 == o2
133 // positive value if o1 > o2
134 inline static int compare(oop o1, oop o2) {
135 void* o1_addr = (void*)o1;
136 void* o2_addr = (void*)o2;
137 if (o1_addr < o2_addr) {
138 return -1;
139 } else if (o1_addr > o2_addr) {
140 return 1;
141 } else {
142 return 0;
143 }
144 }
145
146 // Access to fields in a instanceOop through these methods.
147 template <DecoratorSet decorator>
148 oop obj_field_access(int offset) const;
149 oop obj_field(int offset) const;
150 void obj_field_put(int offset, oop value);
151 void obj_field_put_raw(int offset, oop value);
152 void obj_field_put_volatile(int offset, oop value);
153
154 Metadata* metadata_field(int offset) const;
155 void metadata_field_put(int offset, Metadata* value);
156
157 Metadata* metadata_field_acquire(int offset) const;
158 void release_metadata_field_put(int offset, Metadata* value);
159
160 jbyte byte_field(int offset) const;
161 void byte_field_put(int offset, jbyte contents);
162
163 jchar char_field(int offset) const;
164 void char_field_put(int offset, jchar contents);
165
166 jboolean bool_field(int offset) const;
167 void bool_field_put(int offset, jboolean contents);
168 jboolean bool_field_volatile(int offset) const;
169 void bool_field_put_volatile(int offset, jboolean contents);
170
171 jint int_field(int offset) const;
172 void int_field_put(int offset, jint contents);
173
174 jshort short_field(int offset) const;
175 void short_field_put(int offset, jshort contents);
176
177 jlong long_field(int offset) const;
178 void long_field_put(int offset, jlong contents);
179
180 jfloat float_field(int offset) const;
181 void float_field_put(int offset, jfloat contents);
182
183 jdouble double_field(int offset) const;
184 void double_field_put(int offset, jdouble contents);
185
186 address address_field(int offset) const;
187 void address_field_put(int offset, address contents);
188
189 oop obj_field_acquire(int offset) const;
190 void release_obj_field_put(int offset, oop value);
191
192 jbyte byte_field_acquire(int offset) const;
193 void release_byte_field_put(int offset, jbyte contents);
194
195 jchar char_field_acquire(int offset) const;
196 void release_char_field_put(int offset, jchar contents);
197
198 jboolean bool_field_acquire(int offset) const;
199 void release_bool_field_put(int offset, jboolean contents);
200
201 jint int_field_acquire(int offset) const;
202 void release_int_field_put(int offset, jint contents);
203
204 jshort short_field_acquire(int offset) const;
205 void release_short_field_put(int offset, jshort contents);
206
207 jlong long_field_acquire(int offset) const;
208 void release_long_field_put(int offset, jlong contents);
209
210 jfloat float_field_acquire(int offset) const;
211 void release_float_field_put(int offset, jfloat contents);
212
213 jdouble double_field_acquire(int offset) const;
214 void release_double_field_put(int offset, jdouble contents);
215
216 address address_field_acquire(int offset) const;
217 void release_address_field_put(int offset, address contents);
218
219 // printing functions for VM debugging
220 void print_on(outputStream* st) const; // First level print
221 void print_value_on(outputStream* st) const; // Second level print.
222 void print_address_on(outputStream* st) const; // Address printing
223
224 // printing on default output stream
225 void print();
226 void print_value();
227 void print_address();
228
229 // return the print strings
230 char* print_string();
231 char* print_value_string();
232
233 // verification operations
234 static void verify_on(outputStream* st, oopDesc* oop_desc);
235 static void verify(oopDesc* oopDesc);
236
237 // locking operations
238 inline bool is_locked() const;
239 inline bool is_unlocked() const;
240
241 // asserts and guarantees
242 static bool is_oop(oop obj, bool ignore_mark_word = false);
243 static bool is_oop_or_null(oop obj, bool ignore_mark_word = false);
244
245 // garbage collection
246 inline bool is_gc_marked() const;
247
248 // Forward pointer operations for scavenge
249 inline bool is_forwarded() const;
250
251 void verify_forwardee(oop forwardee) NOT_DEBUG_RETURN;
252
253 inline void forward_to(oop p);
254 inline void forward_to_self();
255
256 // Like "forward_to", but inserts the forwarding pointer atomically.
257 // Exactly one thread succeeds in inserting the forwarding pointer, and
258 // this call returns "NULL" for that thread; any other thread has the
259 // value of the forwarding pointer returned and does not modify "this".
260 inline oop forward_to_atomic(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
261 inline oop forward_to_self_atomic(markWord compare, atomic_memory_order order = memory_order_conservative);
262
263 inline oop forwardee() const;
264 inline oop forwardee(markWord header) const;
265
266 // Age of object during scavenge
267 inline uint age() const;
268 inline void incr_age();
269
270 template <typename OopClosureType>
271 inline void oop_iterate(OopClosureType* cl);
272
273 template <typename OopClosureType>
274 inline void oop_iterate(OopClosureType* cl, MemRegion mr);
275
276 template <typename OopClosureType>
277 inline size_t oop_iterate_size(OopClosureType* cl);
278
279 template <typename OopClosureType>
280 inline size_t oop_iterate_size(OopClosureType* cl, MemRegion mr);
281
282 template <typename OopClosureType>
283 inline void oop_iterate_backwards(OopClosureType* cl);
284
285 template <typename OopClosureType>
286 inline void oop_iterate_backwards(OopClosureType* cl, Klass* klass);
287
288 inline static bool is_instanceof_or_null(oop obj, Klass* klass);
289
290 // identity hash; returns the identity hash key (computes it if necessary)
291 inline intptr_t identity_hash();
292 intptr_t slow_identity_hash();
293
294 // marks are forwarded to stack when object is locked
295 inline bool has_displaced_mark() const;
296 inline markWord displaced_mark() const;
297 inline void set_displaced_mark(markWord m);
298
299 // Checks if the mark word needs to be preserved
300 inline bool mark_must_be_preserved() const;
301 inline bool mark_must_be_preserved(markWord m) const;
302
303 // for code generation
304 static int mark_offset_in_bytes() { return offset_of(oopDesc, _mark); }
305 static int klass_offset_in_bytes() {
306 #ifdef _LP64
307 STATIC_ASSERT(markWord::klass_shift % 8 == 0);
308 return mark_offset_in_bytes() + markWord::klass_shift / 8;
309 #else
310 return offset_of(oopDesc, _klass);
311 #endif
312 }
313
314 // for error reporting
315 static void* load_klass_raw(oop obj);
316 static void* load_oop_raw(oop obj, int offset);
317
318 // Runtime entry
319 #ifdef _LP64
320 static narrowKlass load_nklass_runtime(oopDesc* o);
321 #endif
322
323 // Avoid include gc_globals.hpp in oop.inline.hpp
324 DEBUG_ONLY(bool get_UseParallelGC();)
325 DEBUG_ONLY(bool get_UseG1GC();)
326 };
327
328 // An oopDesc is not initialized via a constructor. Space is allocated in
329 // the Java heap, and static functions provided here on HeapWord* are used
330 // to fill in certain parts of that memory. The allocated memory is then
331 // treated as referring to an oopDesc. For that to be valid, the oopDesc
332 // class must have a trivial default constructor (C++14 3.8/1).
333 static_assert(std::is_trivially_default_constructible<oopDesc>::value, "required");
334
335 #endif // SHARE_OOPS_OOP_HPP