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