1 /*
2 * Copyright (c) 1997, 2024, 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.
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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.
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23 */
24
25 #ifndef SHARE_OOPS_KLASS_HPP
26 #define SHARE_OOPS_KLASS_HPP
27
28 #include "memory/iterator.hpp"
29 #include "memory/memRegion.hpp"
30 #include "oops/klassFlags.hpp"
31 #include "oops/markWord.hpp"
32 #include "oops/metadata.hpp"
33 #include "oops/oop.hpp"
34 #include "oops/oopHandle.hpp"
35 #include "utilities/accessFlags.hpp"
36 #include "utilities/macros.hpp"
37 #if INCLUDE_JFR
38 #include "jfr/support/jfrTraceIdExtension.hpp"
39 #endif
40
41 //
42 // A Klass provides:
43 // 1: language level class object (method dictionary etc.)
44 // 2: provide vm dispatch behavior for the object
45 // Both functions are combined into one C++ class.
46
47 // One reason for the oop/klass dichotomy in the implementation is
48 // that we don't want a C++ vtbl pointer in every object. Thus,
49 // normal oops don't have any virtual functions. Instead, they
50 // forward all "virtual" functions to their klass, which does have
51 // a vtbl and does the C++ dispatch depending on the object's
52 // actual type. (See oop.inline.hpp for some of the forwarding code.)
53 // ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"!
54
55 // Forward declarations.
56 template <class T> class Array;
57 template <class T> class GrowableArray;
58 class ClassLoaderData;
59 class fieldDescriptor;
60 class klassVtable;
61 class ModuleEntry;
62 class PackageEntry;
63 class ParCompactionManager;
64 class PSPromotionManager;
65 class vtableEntry;
66
67 class Klass : public Metadata {
68 friend class VMStructs;
69 friend class JVMCIVMStructs;
70 public:
71 // Klass Kinds for all subclasses of Klass
72 enum KlassKind {
73 InstanceKlassKind,
74 InstanceRefKlassKind,
75 InstanceMirrorKlassKind,
76 InstanceClassLoaderKlassKind,
77 InstanceStackChunkKlassKind,
78 TypeArrayKlassKind,
79 ObjArrayKlassKind,
80 UnknownKlassKind
81 };
82
83 static const uint KLASS_KIND_COUNT = ObjArrayKlassKind + 1;
84 protected:
85
86 // If you add a new field that points to any metaspace object, you
87 // must add this field to Klass::metaspace_pointers_do().
88
89 // note: put frequently-used fields together at start of klass structure
90 // for better cache behavior (may not make much of a difference but sure won't hurt)
91 enum { _primary_super_limit = 8 };
92
93 // The "layout helper" is a combined descriptor of object layout.
94 // For klasses which are neither instance nor array, the value is zero.
95 //
96 // For instances, layout helper is a positive number, the instance size.
97 // This size is already passed through align_object_size and scaled to bytes.
98 // The low order bit is set if instances of this class cannot be
99 // allocated using the fastpath.
100 //
101 // For arrays, layout helper is a negative number, containing four
102 // distinct bytes, as follows:
103 // MSB:[tag, hsz, ebt, log2(esz)]:LSB
104 // where:
105 // tag is 0x80 if the elements are oops, 0xC0 if non-oops
106 // hsz is array header size in bytes (i.e., offset of first element)
107 // ebt is the BasicType of the elements
108 // esz is the element size in bytes
109 // This packed word is arranged so as to be quickly unpacked by the
110 // various fast paths that use the various subfields.
111 //
112 // The esz bits can be used directly by a SLL instruction, without masking.
113 //
114 // Note that the array-kind tag looks like 0x00 for instance klasses,
115 // since their length in bytes is always less than 24Mb.
116 //
117 // Final note: This comes first, immediately after C++ vtable,
118 // because it is frequently queried.
119 jint _layout_helper;
120
121 // Klass kind used to resolve the runtime type of the instance.
122 // - Used to implement devirtualized oop closure dispatching.
123 // - Various type checking in the JVM
124 const KlassKind _kind;
125
126 // Processed access flags, for use by Class.getModifiers.
127 jint _modifier_flags;
128
129 // The fields _super_check_offset, _secondary_super_cache, _secondary_supers
130 // and _primary_supers all help make fast subtype checks. See big discussion
131 // in doc/server_compiler/checktype.txt
132 //
133 // Where to look to observe a supertype (it is &_secondary_super_cache for
134 // secondary supers, else is &_primary_supers[depth()].
135 juint _super_check_offset;
136
137 // Class name. Instance classes: java/lang/String, etc. Array classes: [I,
138 // [Ljava/lang/String;, etc. Set to zero for all other kinds of classes.
139 Symbol* _name;
140
141 // Cache of last observed secondary supertype
142 Klass* _secondary_super_cache;
143 // Array of all secondary supertypes
144 Array<Klass*>* _secondary_supers;
145 // Ordered list of all primary supertypes
146 Klass* _primary_supers[_primary_super_limit];
147 // java/lang/Class instance mirroring this class
148 OopHandle _java_mirror;
149 // Superclass
150 Klass* _super;
151 // First subclass (null if none); _subklass->next_sibling() is next one
152 Klass* volatile _subklass;
153 // Sibling link (or null); links all subklasses of a klass
154 Klass* volatile _next_sibling;
155
156 // All klasses loaded by a class loader are chained through these links
157 Klass* _next_link;
158
159 // The VM's representation of the ClassLoader used to load this class.
160 // Provide access the corresponding instance java.lang.ClassLoader.
161 ClassLoaderData* _class_loader_data;
162
163
164 int _vtable_len; // vtable length. This field may be read very often when we
165 // have lots of itable dispatches (e.g., lambdas and streams).
166 // Keep it away from the beginning of a Klass to avoid cacheline
167 // contention that may happen when a nearby object is modified.
168 AccessFlags _access_flags; // Access flags. The class/interface distinction is stored here.
169 // Some flags created by the JVM, not in the class file itself,
170 // are in _misc_flags below.
171
172 JFR_ONLY(DEFINE_TRACE_ID_FIELD;)
173
174 // Bitmap and hash code used by hashed secondary supers.
175 uintx _bitmap;
176 uint8_t _hash_slot;
177
178 private:
179 // This is an index into FileMapHeader::_shared_path_table[], to
180 // associate this class with the JAR file where it's loaded from during
181 // dump time. If a class is not loaded from the shared archive, this field is
182 // -1.
183 s2 _shared_class_path_index;
184
185 #if INCLUDE_CDS
186 // Various attributes for shared classes. Should be zero for a non-shared class.
187 u2 _shared_class_flags;
188 enum CDSSharedClassFlags {
189 _is_shared_class = 1 << 0, // shadows MetaspaceObj::is_shared
190 _archived_lambda_proxy_is_available = 1 << 1,
191 _has_value_based_class_annotation = 1 << 2,
192 _verified_at_dump_time = 1 << 3,
193 _has_archived_enum_objs = 1 << 4,
194 // This class was not loaded from a classfile in the module image
195 // or classpath.
196 _is_generated_shared_class = 1 << 5
197 };
198 #endif
199
200 KlassFlags _misc_flags;
201
202 CDS_JAVA_HEAP_ONLY(int _archived_mirror_index;)
203
204 protected:
205
206 Klass(KlassKind kind);
207 Klass();
208
209 public:
210 int kind() { return _kind; }
211
212 enum class DefaultsLookupMode { find, skip };
213 enum class OverpassLookupMode { find, skip };
214 enum class StaticLookupMode { find, skip };
215 enum class PrivateLookupMode { find, skip };
216
217 virtual bool is_klass() const { return true; }
218
219 // super() cannot be InstanceKlass* -- Java arrays are covariant, and _super is used
220 // to implement that. NB: the _super of "[Ljava/lang/Integer;" is "[Ljava/lang/Number;"
221 // If this is not what your code expects, you're probably looking for Klass::java_super().
222 Klass* super() const { return _super; }
223 void set_super(Klass* k) { _super = k; }
224
225 // initializes _super link, _primary_supers & _secondary_supers arrays
226 void initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS);
227
228 // klass-specific helper for initializing _secondary_supers
229 virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots,
230 Array<InstanceKlass*>* transitive_interfaces);
231
232 // java_super is the Java-level super type as specified by Class.getSuperClass.
233 virtual InstanceKlass* java_super() const { return nullptr; }
234
235 juint super_check_offset() const { return _super_check_offset; }
236 void set_super_check_offset(juint o) { _super_check_offset = o; }
237
238 Klass* secondary_super_cache() const { return _secondary_super_cache; }
239 void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; }
240
241 Array<Klass*>* secondary_supers() const { return _secondary_supers; }
242 void set_secondary_supers(Array<Klass*>* k);
243 void set_secondary_supers(Array<Klass*>* k, uintx bitmap);
244
245 uint8_t hash_slot() const { return _hash_slot; }
246
247 // Return the element of the _super chain of the given depth.
248 // If there is no such element, return either null or this.
249 Klass* primary_super_of_depth(juint i) const {
250 assert(i < primary_super_limit(), "oob");
251 Klass* super = _primary_supers[i];
252 assert(super == nullptr || super->super_depth() == i, "correct display");
253 return super;
254 }
255
256 // Can this klass be a primary super? False for interfaces and arrays of
257 // interfaces. False also for arrays or classes with long super chains.
258 bool can_be_primary_super() const {
259 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
260 return super_check_offset() != secondary_offset;
261 }
262 virtual bool can_be_primary_super_slow() const;
263
264 // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit].
265 juint super_depth() const {
266 if (!can_be_primary_super()) {
267 return primary_super_limit();
268 } else {
269 juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*);
270 assert(d < primary_super_limit(), "oob");
271 assert(_primary_supers[d] == this, "proper init");
272 return d;
273 }
274 }
275
276 // java mirror
277 oop java_mirror() const;
278 oop java_mirror_no_keepalive() const;
279 void set_java_mirror(Handle m);
280
281 oop archived_java_mirror() NOT_CDS_JAVA_HEAP_RETURN_(nullptr);
282 void set_archived_java_mirror(int mirror_index) NOT_CDS_JAVA_HEAP_RETURN;
283
284 // Temporary mirror switch used by RedefineClasses
285 OopHandle java_mirror_handle() const { return _java_mirror; }
286 void swap_java_mirror_handle(OopHandle& mirror) { _java_mirror.swap(mirror); }
287
288 // Set java mirror OopHandle to null for CDS
289 // This leaves the OopHandle in the CLD, but that's ok, you can't release them.
290 void clear_java_mirror_handle() { _java_mirror = OopHandle(); }
291
292 // modifier flags
293 jint modifier_flags() const { return _modifier_flags; }
294 void set_modifier_flags(jint flags) { _modifier_flags = flags; }
295
296 // size helper
297 int layout_helper() const { return _layout_helper; }
298 void set_layout_helper(int lh) { _layout_helper = lh; }
299
300 // Note: for instances layout_helper() may include padding.
301 // Use InstanceKlass::contains_field_offset to classify field offsets.
302
303 // sub/superklass links
304 Klass* subklass(bool log = false) const;
305 Klass* next_sibling(bool log = false) const;
306
307 InstanceKlass* superklass() const;
308 void append_to_sibling_list(); // add newly created receiver to superklass' subklass list
309
310 void set_next_link(Klass* k) { _next_link = k; }
311 Klass* next_link() const { return _next_link; } // The next klass defined by the class loader.
312 Klass** next_link_addr() { return &_next_link; }
313
314 // class loader data
315 ClassLoaderData* class_loader_data() const { return _class_loader_data; }
316 void set_class_loader_data(ClassLoaderData* loader_data) { _class_loader_data = loader_data; }
317
318 s2 shared_classpath_index() const {
319 return _shared_class_path_index;
320 };
321
322 void set_shared_classpath_index(s2 index) {
323 _shared_class_path_index = index;
324 };
325
326 bool has_archived_mirror_index() const {
327 CDS_JAVA_HEAP_ONLY(return _archived_mirror_index >= 0;)
328 NOT_CDS_JAVA_HEAP(return false);
329 }
330
331 void clear_archived_mirror_index() NOT_CDS_JAVA_HEAP_RETURN;
332
333 void set_lambda_proxy_is_available() {
334 CDS_ONLY(_shared_class_flags |= _archived_lambda_proxy_is_available;)
335 }
336 void clear_lambda_proxy_is_available() {
337 CDS_ONLY(_shared_class_flags &= (u2)(~_archived_lambda_proxy_is_available);)
338 }
339 bool lambda_proxy_is_available() const {
340 CDS_ONLY(return (_shared_class_flags & _archived_lambda_proxy_is_available) != 0;)
341 NOT_CDS(return false;)
342 }
343
344 void set_has_value_based_class_annotation() {
345 CDS_ONLY(_shared_class_flags |= _has_value_based_class_annotation;)
346 }
347 void clear_has_value_based_class_annotation() {
348 CDS_ONLY(_shared_class_flags &= (u2)(~_has_value_based_class_annotation);)
349 }
350 bool has_value_based_class_annotation() const {
351 CDS_ONLY(return (_shared_class_flags & _has_value_based_class_annotation) != 0;)
352 NOT_CDS(return false;)
353 }
354
355 void set_verified_at_dump_time() {
356 CDS_ONLY(_shared_class_flags |= _verified_at_dump_time;)
357 }
358 bool verified_at_dump_time() const {
359 CDS_ONLY(return (_shared_class_flags & _verified_at_dump_time) != 0;)
360 NOT_CDS(return false;)
361 }
362
363 void set_has_archived_enum_objs() {
364 CDS_ONLY(_shared_class_flags |= _has_archived_enum_objs;)
365 }
366 bool has_archived_enum_objs() const {
367 CDS_ONLY(return (_shared_class_flags & _has_archived_enum_objs) != 0;)
368 NOT_CDS(return false;)
369 }
370
371 void set_is_generated_shared_class() {
372 CDS_ONLY(_shared_class_flags |= _is_generated_shared_class;)
373 }
374 bool is_generated_shared_class() const {
375 CDS_ONLY(return (_shared_class_flags & _is_generated_shared_class) != 0;)
376 NOT_CDS(return false;)
377 }
378
379 bool is_shared() const { // shadows MetaspaceObj::is_shared)()
380 CDS_ONLY(return (_shared_class_flags & _is_shared_class) != 0;)
381 NOT_CDS(return false;)
382 }
383
384 void set_is_shared() {
385 CDS_ONLY(_shared_class_flags |= _is_shared_class;)
386 }
387
388 // Obtain the module or package for this class
389 virtual ModuleEntry* module() const = 0;
390 virtual PackageEntry* package() const = 0;
391
392 protected: // internal accessors
393 void set_subklass(Klass* s);
394 void set_next_sibling(Klass* s);
395
396 private:
397 static uint8_t compute_hash_slot(Symbol* s);
398 static void hash_insert(Klass* klass, GrowableArray<Klass*>* secondaries, uintx& bitmap);
399 static uintx hash_secondary_supers(Array<Klass*>* secondaries, bool rewrite);
400
401 public:
402 // Secondary supers table support
403 static Array<Klass*>* pack_secondary_supers(ClassLoaderData* loader_data,
404 GrowableArray<Klass*>* primaries,
405 GrowableArray<Klass*>* secondaries,
406 uintx& bitmap,
407 TRAPS);
408
409 static uintx compute_secondary_supers_bitmap(Array<Klass*>* secondary_supers);
410 static uint8_t compute_home_slot(Klass* k, uintx bitmap);
411
412 static constexpr int SECONDARY_SUPERS_TABLE_SIZE = sizeof(_bitmap) * 8;
413 static constexpr int SECONDARY_SUPERS_TABLE_MASK = SECONDARY_SUPERS_TABLE_SIZE - 1;
414
415 static constexpr uintx SECONDARY_SUPERS_BITMAP_EMPTY = 0;
416 static constexpr uintx SECONDARY_SUPERS_BITMAP_FULL = ~(uintx)0;
417
418 // Compiler support
419 static ByteSize super_offset() { return byte_offset_of(Klass, _super); }
420 static ByteSize super_check_offset_offset() { return byte_offset_of(Klass, _super_check_offset); }
421 static ByteSize primary_supers_offset() { return byte_offset_of(Klass, _primary_supers); }
422 static ByteSize secondary_super_cache_offset() { return byte_offset_of(Klass, _secondary_super_cache); }
423 static ByteSize secondary_supers_offset() { return byte_offset_of(Klass, _secondary_supers); }
424 static ByteSize java_mirror_offset() { return byte_offset_of(Klass, _java_mirror); }
425 static ByteSize class_loader_data_offset() { return byte_offset_of(Klass, _class_loader_data); }
426 static ByteSize modifier_flags_offset() { return byte_offset_of(Klass, _modifier_flags); }
427 static ByteSize layout_helper_offset() { return byte_offset_of(Klass, _layout_helper); }
428 static ByteSize access_flags_offset() { return byte_offset_of(Klass, _access_flags); }
429 #if INCLUDE_JVMCI
430 static ByteSize subklass_offset() { return byte_offset_of(Klass, _subklass); }
431 static ByteSize next_sibling_offset() { return byte_offset_of(Klass, _next_sibling); }
432 #endif
433 static ByteSize bitmap_offset() { return byte_offset_of(Klass, _bitmap); }
434 static ByteSize misc_flags_offset() { return byte_offset_of(Klass, _misc_flags._flags); }
435
436 // Unpacking layout_helper:
437 static const int _lh_neutral_value = 0; // neutral non-array non-instance value
438 static const int _lh_instance_slow_path_bit = 0x01;
439 static const int _lh_log2_element_size_shift = BitsPerByte*0;
440 static const int _lh_log2_element_size_mask = BitsPerLong-1;
441 static const int _lh_element_type_shift = BitsPerByte*1;
442 static const int _lh_element_type_mask = right_n_bits(BitsPerByte); // shifted mask
443 static const int _lh_header_size_shift = BitsPerByte*2;
444 static const int _lh_header_size_mask = right_n_bits(BitsPerByte); // shifted mask
445 static const int _lh_array_tag_bits = 2;
446 static const int _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits;
447 static const int _lh_array_tag_obj_value = ~0x01; // 0x80000000 >> 30
448
449 static const unsigned int _lh_array_tag_type_value = 0Xffffffff; // ~0x00, // 0xC0000000 >> 30
450
451 static int layout_helper_size_in_bytes(jint lh) {
452 assert(lh > (jint)_lh_neutral_value, "must be instance");
453 return (int) lh & ~_lh_instance_slow_path_bit;
454 }
455 static bool layout_helper_needs_slow_path(jint lh) {
456 assert(lh > (jint)_lh_neutral_value, "must be instance");
457 return (lh & _lh_instance_slow_path_bit) != 0;
458 }
459 static bool layout_helper_is_instance(jint lh) {
460 return (jint)lh > (jint)_lh_neutral_value;
461 }
462 static bool layout_helper_is_array(jint lh) {
463 return (jint)lh < (jint)_lh_neutral_value;
464 }
465 static bool layout_helper_is_typeArray(jint lh) {
466 // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
467 return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
468 }
469 static bool layout_helper_is_objArray(jint lh) {
470 // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
471 return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
472 }
473 static int layout_helper_header_size(jint lh) {
474 assert(lh < (jint)_lh_neutral_value, "must be array");
475 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
476 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
477 return hsize;
478 }
479 static BasicType layout_helper_element_type(jint lh) {
480 assert(lh < (jint)_lh_neutral_value, "must be array");
481 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
482 assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
483 return (BasicType) btvalue;
484 }
485
486 // Want a pattern to quickly diff against layout header in register
487 // find something less clever!
488 static int layout_helper_boolean_diffbit() {
489 jint zlh = array_layout_helper(T_BOOLEAN);
490 jint blh = array_layout_helper(T_BYTE);
491 assert(zlh != blh, "array layout helpers must differ");
492 int diffbit = 1;
493 while ((diffbit & (zlh ^ blh)) == 0 && (diffbit & zlh) == 0) {
494 diffbit <<= 1;
495 assert(diffbit != 0, "make sure T_BOOLEAN has a different bit than T_BYTE");
496 }
497 return diffbit;
498 }
499
500 static int layout_helper_log2_element_size(jint lh) {
501 assert(lh < (jint)_lh_neutral_value, "must be array");
502 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
503 assert(l2esz <= LogBytesPerLong,
504 "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh);
505 return l2esz;
506 }
507 static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
508 return (tag << _lh_array_tag_shift)
509 | (hsize << _lh_header_size_shift)
510 | ((int)etype << _lh_element_type_shift)
511 | (log2_esize << _lh_log2_element_size_shift);
512 }
513 static jint instance_layout_helper(jint size, bool slow_path_flag) {
514 return (size << LogBytesPerWord)
515 | (slow_path_flag ? _lh_instance_slow_path_bit : 0);
516 }
517 static int layout_helper_to_size_helper(jint lh) {
518 assert(lh > (jint)_lh_neutral_value, "must be instance");
519 // Note that the following expression discards _lh_instance_slow_path_bit.
520 return lh >> LogBytesPerWord;
521 }
522 // Out-of-line version computes everything based on the etype:
523 static jint array_layout_helper(BasicType etype);
524
525 // What is the maximum number of primary superclasses any klass can have?
526 static juint primary_super_limit() { return _primary_super_limit; }
527
528 // vtables
529 klassVtable vtable() const;
530 int vtable_length() const { return _vtable_len; }
531
532 // subclass check
533 bool is_subclass_of(const Klass* k) const;
534 // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
535 bool is_subtype_of(Klass* k) const {
536 juint off = k->super_check_offset();
537 Klass* sup = *(Klass**)( (address)this + off );
538 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
539 if (sup == k) {
540 return true;
541 } else if (off != secondary_offset) {
542 return false;
543 } else {
544 return search_secondary_supers(k);
545 }
546 }
547
548 bool search_secondary_supers(Klass* k) const;
549
550 // Find LCA in class hierarchy
551 Klass *LCA( Klass *k );
552
553 // Check whether reflection/jni/jvm code is allowed to instantiate this class;
554 // if not, throw either an Error or an Exception.
555 virtual void check_valid_for_instantiation(bool throwError, TRAPS);
556
557 // array copying
558 virtual void copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
559
560 // tells if the class should be initialized
561 virtual bool should_be_initialized() const { return false; }
562 // initializes the klass
563 virtual void initialize(TRAPS);
564 virtual Klass* find_field(Symbol* name, Symbol* signature, fieldDescriptor* fd) const;
565 virtual Method* uncached_lookup_method(const Symbol* name, const Symbol* signature,
566 OverpassLookupMode overpass_mode,
567 PrivateLookupMode = PrivateLookupMode::find) const;
568 public:
569 Method* lookup_method(const Symbol* name, const Symbol* signature) const {
570 return uncached_lookup_method(name, signature, OverpassLookupMode::find);
571 }
572
573 // array class with specific rank
574 virtual ArrayKlass* array_klass(int rank, TRAPS) = 0;
575
576 // array class with this klass as element type
577 virtual ArrayKlass* array_klass(TRAPS) = 0;
578
579 // These will return null instead of allocating on the heap:
580 virtual ArrayKlass* array_klass_or_null(int rank) = 0;
581 virtual ArrayKlass* array_klass_or_null() = 0;
582
583 virtual oop protection_domain() const = 0;
584
585 oop class_loader() const;
586
587 inline oop klass_holder() const;
588
589 protected:
590
591 // Error handling when length > max_length or length < 0
592 static void check_array_allocation_length(int length, int max_length, TRAPS);
593
594 void set_vtable_length(int len) { _vtable_len= len; }
595
596 vtableEntry* start_of_vtable() const;
597 #if INCLUDE_CDS
598 void restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS);
599 #endif
600 public:
601 Method* method_at_vtable(int index);
602
603 static ByteSize vtable_start_offset();
604 static ByteSize vtable_length_offset() {
605 return byte_offset_of(Klass, _vtable_len);
606 }
607
608 #if INCLUDE_CDS
609 // CDS support - remove and restore oops from metadata. Oops are not shared.
610 virtual void remove_unshareable_info();
611 virtual void remove_java_mirror();
612
613 bool is_unshareable_info_restored() const {
614 assert(is_shared(), "use this for shared classes only");
615 if (has_archived_mirror_index()) {
616 // _java_mirror is not a valid OopHandle but rather an encoded reference in the shared heap
617 return false;
618 } else if (_java_mirror.is_empty()) {
619 return false;
620 } else {
621 return true;
622 }
623 }
624 #endif // INCLUDE_CDS
625
626 public:
627 // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
628 // These functions describe behavior for the oop not the KLASS.
629
630 // actual oop size of obj in memory in word size.
631 virtual size_t oop_size(oop obj) const = 0;
632
633 // Size of klass in word size.
634 virtual int size() const = 0;
635
636 // Returns the Java name for a class (Resource allocated)
637 // For arrays, this returns the name of the element with a leading '['.
638 // For classes, this returns the name with the package separators
639 // turned into '.'s.
640 const char* external_name() const;
641 // Returns the name for a class (Resource allocated) as the class
642 // would appear in a signature.
643 // For arrays, this returns the name of the element with a leading '['.
644 // For classes, this returns the name with a leading 'L' and a trailing ';'
645 // and the package separators as '/'.
646 virtual const char* signature_name() const;
647
648 const char* joint_in_module_of_loader(const Klass* class2, bool include_parent_loader = false) const;
649 const char* class_in_module_of_loader(bool use_are = false, bool include_parent_loader = false) const;
650
651 // Returns "interface", "abstract class" or "class".
652 const char* external_kind() const;
653
654 // type testing operations
655 #ifdef ASSERT
656 protected:
657 virtual bool is_instance_klass_slow() const { return false; }
658 virtual bool is_array_klass_slow() const { return false; }
659 virtual bool is_objArray_klass_slow() const { return false; }
660 virtual bool is_typeArray_klass_slow() const { return false; }
661 #endif // ASSERT
662 public:
663
664 // Fast non-virtual versions
665 #ifndef ASSERT
666 #define assert_same_query(xval, xcheck) xval
667 #else
668 private:
669 static bool assert_same_query(bool xval, bool xslow) {
670 assert(xval == xslow, "slow and fast queries agree");
671 return xval;
672 }
673 public:
674 #endif
675
676 bool is_instance_klass() const { return assert_same_query(_kind <= InstanceStackChunkKlassKind, is_instance_klass_slow()); }
677 // Other is anything that is not one of the more specialized kinds of InstanceKlass.
678 bool is_other_instance_klass() const { return _kind == InstanceKlassKind; }
679 bool is_reference_instance_klass() const { return _kind == InstanceRefKlassKind; }
680 bool is_mirror_instance_klass() const { return _kind == InstanceMirrorKlassKind; }
681 bool is_class_loader_instance_klass() const { return _kind == InstanceClassLoaderKlassKind; }
682 bool is_array_klass() const { return assert_same_query( _kind >= TypeArrayKlassKind, is_array_klass_slow()); }
683 bool is_stack_chunk_instance_klass() const { return _kind == InstanceStackChunkKlassKind; }
684 bool is_objArray_klass() const { return assert_same_query( _kind == ObjArrayKlassKind, is_objArray_klass_slow()); }
685 bool is_typeArray_klass() const { return assert_same_query( _kind == TypeArrayKlassKind, is_typeArray_klass_slow()); }
686 #undef assert_same_query
687
688 // Access flags
689 AccessFlags access_flags() const { return _access_flags; }
690 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
691
692 bool is_public() const { return _access_flags.is_public(); }
693 bool is_final() const { return _access_flags.is_final(); }
694 bool is_interface() const { return _access_flags.is_interface(); }
695 bool is_abstract() const { return _access_flags.is_abstract(); }
696 bool is_super() const { return _access_flags.is_super(); }
697 bool is_synthetic() const { return _access_flags.is_synthetic(); }
698 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
699 bool has_finalizer() const { return _misc_flags.has_finalizer(); }
700 void set_has_finalizer() { _misc_flags.set_has_finalizer(true); }
701 bool is_hidden() const { return _misc_flags.is_hidden_class(); }
702 void set_is_hidden() { _misc_flags.set_is_hidden_class(true); }
703 bool is_value_based() const { return _misc_flags.is_value_based_class(); }
704 void set_is_value_based() { _misc_flags.set_is_value_based_class(true); }
705
706 klass_flags_t misc_flags() const { return _misc_flags.value(); }
707
708 inline bool is_non_strong_hidden() const;
709
710 bool is_cloneable() const;
711 void set_is_cloneable();
712
713 JFR_ONLY(DEFINE_TRACE_ID_METHODS;)
714
715 virtual void metaspace_pointers_do(MetaspaceClosure* iter);
716 virtual MetaspaceObj::Type type() const { return ClassType; }
717
718 inline bool is_loader_alive() const;
719
720 void clean_subklass();
721
722 static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true);
723 static void clean_subklass_tree() {
724 clean_weak_klass_links(/*unloading_occurred*/ true , /* clean_alive_klasses */ false);
725 }
726
727 // Return self, except for abstract classes with exactly 1
728 // implementor. Then return the 1 concrete implementation.
729 Klass *up_cast_abstract();
730
731 // klass name
732 Symbol* name() const { return _name; }
733 void set_name(Symbol* n);
734
735 virtual void release_C_heap_structures(bool release_constant_pool = true);
736
737 public:
738 virtual jint compute_modifier_flags() const = 0;
739
740 // JVMTI support
741 virtual jint jvmti_class_status() const;
742
743 // Printing
744 virtual void print_on(outputStream* st) const;
745
746 virtual void oop_print_value_on(oop obj, outputStream* st);
747 virtual void oop_print_on (oop obj, outputStream* st);
748
749 void print_secondary_supers_on(outputStream* st) const;
750
751 virtual const char* internal_name() const = 0;
752
753 // Verification
754 virtual void verify_on(outputStream* st);
755 void verify() { verify_on(tty); }
756
757 #ifndef PRODUCT
758 bool verify_vtable_index(int index);
759 #endif
760
761 virtual void oop_verify_on(oop obj, outputStream* st);
762
763 // for error reporting
764 static bool is_valid(Klass* k);
765
766 static void on_secondary_supers_verification_failure(Klass* super, Klass* sub, bool linear_result, bool table_result, const char* msg);
767 };
768
769 #endif // SHARE_OOPS_KLASS_HPP