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. 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_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