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.
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_KLASS_HPP
26 #define SHARE_OOPS_KLASS_HPP
27
28 #include "memory/iterator.hpp"
29 #include "memory/memRegion.hpp"
30 #include "oops/markWord.hpp"
31 #include "oops/metadata.hpp"
32 #include "oops/oop.hpp"
33 #include "oops/oopHandle.hpp"
34 #include "utilities/accessFlags.hpp"
35 #include "utilities/macros.hpp"
36 #if INCLUDE_JFR
37 #include "jfr/support/jfrTraceIdExtension.hpp"
38 #endif
39
40 //
41 // A Klass provides:
42 // 1: language level class object (method dictionary etc.)
43 // 2: provide vm dispatch behavior for the object
44 // Both functions are combined into one C++ class.
45
46 // One reason for the oop/klass dichotomy in the implementation is
47 // that we don't want a C++ vtbl pointer in every object. Thus,
48 // normal oops don't have any virtual functions. Instead, they
49 // forward all "virtual" functions to their klass, which does have
50 // a vtbl and does the C++ dispatch depending on the object's
51 // actual type. (See oop.inline.hpp for some of the forwarding code.)
52 // ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"!
53
54 // Forward declarations.
55 template <class T> class Array;
56 template <class T> class GrowableArray;
57 class ClassLoaderData;
58 class fieldDescriptor;
59 class klassVtable;
60 class ModuleEntry;
61 class PackageEntry;
62 class ParCompactionManager;
63 class PSPromotionManager;
64 class vtableEntry;
65
66 class Klass : public Metadata {
67 friend class VMStructs;
68 friend class JVMCIVMStructs;
69 public:
70 // Klass Kinds for all subclasses of Klass
71 enum KlassKind {
72 InstanceKlassKind,
73 InstanceRefKlassKind,
74 InstanceMirrorKlassKind,
75 InstanceClassLoaderKlassKind,
76 InstanceStackChunkKlassKind,
77 TypeArrayKlassKind,
78 ObjArrayKlassKind,
79 UnknownKlassKind
80 };
81
82 static const uint KLASS_KIND_COUNT = ObjArrayKlassKind + 1;
83 protected:
84
85 // If you add a new field that points to any metaspace object, you
86 // must add this field to Klass::metaspace_pointers_do().
87
88 // note: put frequently-used fields together at start of klass structure
89 // for better cache behavior (may not make much of a difference but sure won't hurt)
90 enum { _primary_super_limit = 8 };
91
92 // The "layout helper" is a combined descriptor of object layout.
93 // For klasses which are neither instance nor array, the value is zero.
94 //
95 // For instances, layout helper is a positive number, the instance size.
96 // This size is already passed through align_object_size and scaled to bytes.
97 // The low order bit is set if instances of this class cannot be
98 // allocated using the fastpath.
99 //
100 // For arrays, layout helper is a negative number, containing four
101 // distinct bytes, as follows:
102 // MSB:[tag, hsz, ebt, log2(esz)]:LSB
103 // where:
104 // tag is 0x80 if the elements are oops, 0xC0 if non-oops
105 // hsz is array header size in bytes (i.e., offset of first element)
106 // ebt is the BasicType of the elements
107 // esz is the element size in bytes
108 // This packed word is arranged so as to be quickly unpacked by the
109 // various fast paths that use the various subfields.
110 //
111 // The esz bits can be used directly by a SLL instruction, without masking.
112 //
113 // Note that the array-kind tag looks like 0x00 for instance klasses,
114 // since their length in bytes is always less than 24Mb.
115 //
116 // Final note: This comes first, immediately after C++ vtable,
117 // because it is frequently queried.
118 jint _layout_helper;
119
120 // Klass kind used to resolve the runtime type of the instance.
121 // - Used to implement devirtualized oop closure dispatching.
122 // - Various type checking in the JVM
123 const KlassKind _kind;
124
125 // Processed access flags, for use by Class.getModifiers.
126 jint _modifier_flags;
127
128 // The fields _super_check_offset, _secondary_super_cache, _secondary_supers
129 // and _primary_supers all help make fast subtype checks. See big discussion
130 // in doc/server_compiler/checktype.txt
131 //
132 // Where to look to observe a supertype (it is &_secondary_super_cache for
133 // secondary supers, else is &_primary_supers[depth()].
134 juint _super_check_offset;
135
136 // Class name. Instance classes: java/lang/String, etc. Array classes: [I,
137 // [Ljava/lang/String;, etc. Set to zero for all other kinds of classes.
138 Symbol* _name;
139
140 // Cache of last observed secondary supertype
141 Klass* _secondary_super_cache;
142 // Array of all secondary supertypes
143 Array<Klass*>* _secondary_supers;
144 // Ordered list of all primary supertypes
145 Klass* _primary_supers[_primary_super_limit];
146 // java/lang/Class instance mirroring this class
147 OopHandle _java_mirror;
148 // Superclass
149 Klass* _super;
150 // First subclass (null if none); _subklass->next_sibling() is next one
151 Klass* volatile _subklass;
152 // Sibling link (or null); links all subklasses of a klass
153 Klass* volatile _next_sibling;
154
155 // All klasses loaded by a class loader are chained through these links
156 Klass* _next_link;
157
158 // The VM's representation of the ClassLoader used to load this class.
159 // Provide access the corresponding instance java.lang.ClassLoader.
160 ClassLoaderData* _class_loader_data;
161
162 // Bitmap and hash code used by hashed secondary supers.
163 uintx _bitmap;
164 uint8_t _hash_slot;
165
166 static uint8_t compute_hash_slot(Symbol* s);
167
168 int _vtable_len; // vtable length. This field may be read very often when we
169 // have lots of itable dispatches (e.g., lambdas and streams).
170 // Keep it away from the beginning of a Klass to avoid cacheline
171 // contention that may happen when a nearby object is modified.
172 AccessFlags _access_flags; // Access flags. The class/interface distinction is stored here.
173
174 JFR_ONLY(DEFINE_TRACE_ID_FIELD;)
175
176 private:
177 // This is an index into FileMapHeader::_shared_path_table[], to
178 // associate this class with the JAR file where it's loaded from during
179 // dump time. If a class is not loaded from the shared archive, this field is
180 // -1.
181 s2 _shared_class_path_index;
182
183 #if INCLUDE_CDS
184 // Various attributes for shared classes. Should be zero for a non-shared class.
185 u2 _shared_class_flags;
186 enum CDSSharedClassFlags {
187 _is_shared_class = 1 << 0, // shadows MetaspaceObj::is_shared
188 _archived_lambda_proxy_is_available = 1 << 1,
189 _has_value_based_class_annotation = 1 << 2,
190 _verified_at_dump_time = 1 << 3,
191 _has_archived_enum_objs = 1 << 4,
192 // This class was not loaded from a classfile in the module image
193 // or classpath.
194 _is_generated_shared_class = 1 << 5,
195 // The archived mirror is already initialized. No need to call <clinit>
196 _has_preinitialized_mirror = 1 << 6,
197 };
198 #endif
199
200 CDS_JAVA_HEAP_ONLY(int _archived_mirror_index;)
201
202 protected:
203
204 Klass(KlassKind kind);
205 Klass();
206
207 void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw();
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 void set_has_preinitialized_mirror() {
380 CDS_ONLY(_shared_class_flags |= _has_preinitialized_mirror;)
381 }
382 bool has_preinitialized_mirror() const {
383 CDS_ONLY(return (_shared_class_flags & _has_preinitialized_mirror) != 0;)
384 NOT_CDS(return false;)
385 }
386
387 bool is_shared() const { // shadows MetaspaceObj::is_shared)()
388 CDS_ONLY(return (_shared_class_flags & _is_shared_class) != 0;)
389 NOT_CDS(return false;)
390 }
391
392 void set_is_shared() {
393 CDS_ONLY(_shared_class_flags |= _is_shared_class;)
394 }
395
396 // Obtain the module or package for this class
397 virtual ModuleEntry* module() const = 0;
398 virtual PackageEntry* package() const = 0;
399
400 protected: // internal accessors
401 void set_subklass(Klass* s);
402 void set_next_sibling(Klass* s);
403
404 private:
405 static void hash_insert(Klass* klass, GrowableArray<Klass*>* secondaries, uintx& bitmap);
406 static uintx hash_secondary_supers(Array<Klass*>* secondaries, bool rewrite);
407
408 public:
409 // Secondary supers table support
410 static Array<Klass*>* pack_secondary_supers(ClassLoaderData* loader_data,
411 GrowableArray<Klass*>* primaries,
412 GrowableArray<Klass*>* secondaries,
413 uintx& bitmap,
414 TRAPS);
415
416 static uintx compute_secondary_supers_bitmap(Array<Klass*>* secondary_supers);
417 static uint8_t compute_home_slot(Klass* k, uintx bitmap);
418
419 static constexpr int SECONDARY_SUPERS_TABLE_SIZE = sizeof(_bitmap) * 8;
420 static constexpr int SECONDARY_SUPERS_TABLE_MASK = SECONDARY_SUPERS_TABLE_SIZE - 1;
421
422 static constexpr uintx SECONDARY_SUPERS_BITMAP_EMPTY = 0;
423 static constexpr uintx SECONDARY_SUPERS_BITMAP_FULL = ~(uintx)0;
424
425 // Compiler support
426 static ByteSize super_offset() { return byte_offset_of(Klass, _super); }
427 static ByteSize super_check_offset_offset() { return byte_offset_of(Klass, _super_check_offset); }
428 static ByteSize primary_supers_offset() { return byte_offset_of(Klass, _primary_supers); }
429 static ByteSize secondary_super_cache_offset() { return byte_offset_of(Klass, _secondary_super_cache); }
430 static ByteSize secondary_supers_offset() { return byte_offset_of(Klass, _secondary_supers); }
431 static ByteSize java_mirror_offset() { return byte_offset_of(Klass, _java_mirror); }
432 static ByteSize class_loader_data_offset() { return byte_offset_of(Klass, _class_loader_data); }
433 static ByteSize modifier_flags_offset() { return byte_offset_of(Klass, _modifier_flags); }
434 static ByteSize layout_helper_offset() { return byte_offset_of(Klass, _layout_helper); }
435 static ByteSize access_flags_offset() { return byte_offset_of(Klass, _access_flags); }
436 #if INCLUDE_JVMCI
437 static ByteSize subklass_offset() { return byte_offset_of(Klass, _subklass); }
438 static ByteSize next_sibling_offset() { return byte_offset_of(Klass, _next_sibling); }
439 #endif
440 static ByteSize bitmap_offset() { return byte_offset_of(Klass, _bitmap); }
441
442 // Unpacking layout_helper:
443 static const int _lh_neutral_value = 0; // neutral non-array non-instance value
444 static const int _lh_instance_slow_path_bit = 0x01;
445 static const int _lh_log2_element_size_shift = BitsPerByte*0;
446 static const int _lh_log2_element_size_mask = BitsPerLong-1;
447 static const int _lh_element_type_shift = BitsPerByte*1;
448 static const int _lh_element_type_mask = right_n_bits(BitsPerByte); // shifted mask
449 static const int _lh_header_size_shift = BitsPerByte*2;
450 static const int _lh_header_size_mask = right_n_bits(BitsPerByte); // shifted mask
451 static const int _lh_array_tag_bits = 2;
452 static const int _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits;
453 static const int _lh_array_tag_obj_value = ~0x01; // 0x80000000 >> 30
454
455 static const unsigned int _lh_array_tag_type_value = 0Xffffffff; // ~0x00, // 0xC0000000 >> 30
456
457 static int layout_helper_size_in_bytes(jint lh) {
458 assert(lh > (jint)_lh_neutral_value, "must be instance");
459 return (int) lh & ~_lh_instance_slow_path_bit;
460 }
461 static bool layout_helper_needs_slow_path(jint lh) {
462 assert(lh > (jint)_lh_neutral_value, "must be instance");
463 return (lh & _lh_instance_slow_path_bit) != 0;
464 }
465 static bool layout_helper_is_instance(jint lh) {
466 return (jint)lh > (jint)_lh_neutral_value;
467 }
468 static bool layout_helper_is_array(jint lh) {
469 return (jint)lh < (jint)_lh_neutral_value;
470 }
471 static bool layout_helper_is_typeArray(jint lh) {
472 // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
473 return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
474 }
475 static bool layout_helper_is_objArray(jint lh) {
476 // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
477 return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
478 }
479 static int layout_helper_header_size(jint lh) {
480 assert(lh < (jint)_lh_neutral_value, "must be array");
481 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
482 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
483 return hsize;
484 }
485 static BasicType layout_helper_element_type(jint lh) {
486 assert(lh < (jint)_lh_neutral_value, "must be array");
487 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
488 assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
489 return (BasicType) btvalue;
490 }
491
492 // Want a pattern to quickly diff against layout header in register
493 // find something less clever!
494 static int layout_helper_boolean_diffbit() {
495 jint zlh = array_layout_helper(T_BOOLEAN);
496 jint blh = array_layout_helper(T_BYTE);
497 assert(zlh != blh, "array layout helpers must differ");
498 int diffbit = 1;
499 while ((diffbit & (zlh ^ blh)) == 0 && (diffbit & zlh) == 0) {
500 diffbit <<= 1;
501 assert(diffbit != 0, "make sure T_BOOLEAN has a different bit than T_BYTE");
502 }
503 return diffbit;
504 }
505
506 static int layout_helper_log2_element_size(jint lh) {
507 assert(lh < (jint)_lh_neutral_value, "must be array");
508 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
509 assert(l2esz <= LogBytesPerLong,
510 "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh);
511 return l2esz;
512 }
513 static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
514 return (tag << _lh_array_tag_shift)
515 | (hsize << _lh_header_size_shift)
516 | ((int)etype << _lh_element_type_shift)
517 | (log2_esize << _lh_log2_element_size_shift);
518 }
519 static jint instance_layout_helper(jint size, bool slow_path_flag) {
520 return (size << LogBytesPerWord)
521 | (slow_path_flag ? _lh_instance_slow_path_bit : 0);
522 }
523 static int layout_helper_to_size_helper(jint lh) {
524 assert(lh > (jint)_lh_neutral_value, "must be instance");
525 // Note that the following expression discards _lh_instance_slow_path_bit.
526 return lh >> LogBytesPerWord;
527 }
528 // Out-of-line version computes everything based on the etype:
529 static jint array_layout_helper(BasicType etype);
530
531 // What is the maximum number of primary superclasses any klass can have?
532 static juint primary_super_limit() { return _primary_super_limit; }
533
534 // vtables
535 klassVtable vtable() const;
536 int vtable_length() const { return _vtable_len; }
537
538 // subclass check
539 bool is_subclass_of(const Klass* k) const;
540 // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
541 bool is_subtype_of(Klass* k) const {
542 juint off = k->super_check_offset();
543 Klass* sup = *(Klass**)( (address)this + off );
544 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
545 if (sup == k) {
546 return true;
547 } else if (off != secondary_offset) {
548 return false;
549 } else {
550 return search_secondary_supers(k);
551 }
552 }
553
554 bool search_secondary_supers(Klass* k) const;
555
556 // Find LCA in class hierarchy
557 Klass *LCA( Klass *k );
558
559 // Check whether reflection/jni/jvm code is allowed to instantiate this class;
560 // if not, throw either an Error or an Exception.
561 virtual void check_valid_for_instantiation(bool throwError, TRAPS);
562
563 // array copying
564 virtual void copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
565
566 // tells if the class should be initialized
567 virtual bool should_be_initialized() const { return false; }
568 // initializes the klass
569 virtual void initialize(TRAPS);
570 virtual Klass* find_field(Symbol* name, Symbol* signature, fieldDescriptor* fd) const;
571 virtual Method* uncached_lookup_method(const Symbol* name, const Symbol* signature,
572 OverpassLookupMode overpass_mode,
573 PrivateLookupMode = PrivateLookupMode::find) const;
574 public:
575 Method* lookup_method(const Symbol* name, const Symbol* signature) const {
576 return uncached_lookup_method(name, signature, OverpassLookupMode::find);
577 }
578
579 // array class with specific rank
580 virtual ArrayKlass* array_klass(int rank, TRAPS) = 0;
581
582 // array class with this klass as element type
583 virtual ArrayKlass* array_klass(TRAPS) = 0;
584
585 // These will return null instead of allocating on the heap:
586 virtual ArrayKlass* array_klass_or_null(int rank) = 0;
587 virtual ArrayKlass* array_klass_or_null() = 0;
588
589 virtual oop protection_domain() const = 0;
590
591 oop class_loader() const;
592 Symbol* class_loader_name_and_id() const;
593
594 inline oop klass_holder() const;
595
596 protected:
597
598 // Error handling when length > max_length or length < 0
599 static void check_array_allocation_length(int length, int max_length, TRAPS);
600
601 void set_vtable_length(int len) { _vtable_len= len; }
602
603 vtableEntry* start_of_vtable() const;
604 #if INCLUDE_CDS
605 void restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS);
606 #endif
607 public:
608 Method* method_at_vtable(int index);
609
610 static ByteSize vtable_start_offset();
611 static ByteSize vtable_length_offset() {
612 return byte_offset_of(Klass, _vtable_len);
613 }
614
615 #if INCLUDE_CDS
616 // CDS support - remove and restore oops from metadata. Oops are not shared.
617 virtual void remove_unshareable_info();
618 virtual void remove_java_mirror();
619
620 bool is_unshareable_info_restored() const {
621 assert(is_shared(), "use this for shared classes only");
622 if (has_archived_mirror_index()) {
623 // _java_mirror is not a valid OopHandle but rather an encoded reference in the shared heap
624 return false;
625 } else if (_java_mirror.is_empty()) {
626 return false;
627 } else {
628 return true;
629 }
630 }
631 #endif // INCLUDE_CDS
632
633 public:
634 // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
635 // These functions describe behavior for the oop not the KLASS.
636
637 // actual oop size of obj in memory in word size.
638 virtual size_t oop_size(oop obj) const = 0;
639
640 // Size of klass in word size.
641 virtual int size() const = 0;
642
643 // Returns the Java name for a class (Resource allocated)
644 // For arrays, this returns the name of the element with a leading '['.
645 // For classes, this returns the name with the package separators
646 // turned into '.'s.
647 const char* external_name() const;
648 // Returns the name for a class (Resource allocated) as the class
649 // would appear in a signature.
650 // For arrays, this returns the name of the element with a leading '['.
651 // For classes, this returns the name with a leading 'L' and a trailing ';'
652 // and the package separators as '/'.
653 virtual const char* signature_name() const;
654
655 const char* joint_in_module_of_loader(const Klass* class2, bool include_parent_loader = false) const;
656 const char* class_in_module_of_loader(bool use_are = false, bool include_parent_loader = false) const;
657
658 // Returns "interface", "abstract class" or "class".
659 const char* external_kind() const;
660
661 // type testing operations
662 #ifdef ASSERT
663 protected:
664 virtual bool is_instance_klass_slow() const { return false; }
665 virtual bool is_array_klass_slow() const { return false; }
666 virtual bool is_objArray_klass_slow() const { return false; }
667 virtual bool is_typeArray_klass_slow() const { return false; }
668 #endif // ASSERT
669 public:
670
671 // Fast non-virtual versions
672 #ifndef ASSERT
673 #define assert_same_query(xval, xcheck) xval
674 #else
675 private:
676 static bool assert_same_query(bool xval, bool xslow) {
677 assert(xval == xslow, "slow and fast queries agree");
678 return xval;
679 }
680 public:
681 #endif
682
683 bool is_instance_klass() const { return assert_same_query(_kind <= InstanceStackChunkKlassKind, is_instance_klass_slow()); }
684 // Other is anything that is not one of the more specialized kinds of InstanceKlass.
685 bool is_other_instance_klass() const { return _kind == InstanceKlassKind; }
686 bool is_reference_instance_klass() const { return _kind == InstanceRefKlassKind; }
687 bool is_mirror_instance_klass() const { return _kind == InstanceMirrorKlassKind; }
688 bool is_class_loader_instance_klass() const { return _kind == InstanceClassLoaderKlassKind; }
689 bool is_array_klass() const { return assert_same_query( _kind >= TypeArrayKlassKind, is_array_klass_slow()); }
690 bool is_stack_chunk_instance_klass() const { return _kind == InstanceStackChunkKlassKind; }
691 bool is_objArray_klass() const { return assert_same_query( _kind == ObjArrayKlassKind, is_objArray_klass_slow()); }
692 bool is_typeArray_klass() const { return assert_same_query( _kind == TypeArrayKlassKind, is_typeArray_klass_slow()); }
693 #undef assert_same_query
694
695 // Access flags
696 AccessFlags access_flags() const { return _access_flags; }
697 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
698
699 bool is_public() const { return _access_flags.is_public(); }
700 bool is_final() const { return _access_flags.is_final(); }
701 bool is_interface() const { return _access_flags.is_interface(); }
702 bool is_abstract() const { return _access_flags.is_abstract(); }
703 bool is_super() const { return _access_flags.is_super(); }
704 bool is_synthetic() const { return _access_flags.is_synthetic(); }
705 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
706 bool has_finalizer() const { return _access_flags.has_finalizer(); }
707 void set_has_finalizer() { _access_flags.set_has_finalizer(); }
708 bool is_hidden() const { return access_flags().is_hidden_class(); }
709 void set_is_hidden() { _access_flags.set_is_hidden_class(); }
710 bool is_value_based() { return _access_flags.is_value_based_class(); }
711 void set_is_value_based() { _access_flags.set_is_value_based_class(); }
712
713 inline bool is_non_strong_hidden() const;
714
715 bool is_cloneable() const;
716 void set_is_cloneable();
717
718 JFR_ONLY(DEFINE_TRACE_ID_METHODS;)
719
720 virtual void metaspace_pointers_do(MetaspaceClosure* iter);
721 virtual MetaspaceObj::Type type() const { return ClassType; }
722
723 inline bool is_loader_alive() const;
724
725 void clean_subklass();
726
727 static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true);
728 static void clean_subklass_tree() {
729 clean_weak_klass_links(/*unloading_occurred*/ true , /* clean_alive_klasses */ false);
730 }
731
732 // Return self, except for abstract classes with exactly 1
733 // implementor. Then return the 1 concrete implementation.
734 Klass *up_cast_abstract();
735
736 // klass name
737 Symbol* name() const { return _name; }
738 void set_name(Symbol* n);
739
740 virtual void release_C_heap_structures(bool release_constant_pool = true);
741
742 public:
743 virtual jint compute_modifier_flags() const = 0;
744
745 // JVMTI support
746 virtual jint jvmti_class_status() const;
747
748 // Printing
749 virtual void print_on(outputStream* st) const;
750
751 virtual void oop_print_value_on(oop obj, outputStream* st);
752 virtual void oop_print_on (oop obj, outputStream* st);
753
754 void print_secondary_supers_on(outputStream* st) const;
755
756 virtual const char* internal_name() const = 0;
757
758 // Verification
759 virtual void verify_on(outputStream* st);
760 void verify() { verify_on(tty); }
761
762 #ifndef PRODUCT
763 bool verify_vtable_index(int index);
764 #endif
765
766 virtual void oop_verify_on(oop obj, outputStream* st);
767
768 // for error reporting
769 static bool is_valid(Klass* k);
770
771 static void on_secondary_supers_verification_failure(Klass* super, Klass* sub, bool linear_result, bool table_result, const char* msg);
772 };
773
774 #endif // SHARE_OOPS_KLASS_HPP