1 /*
2 * Copyright (c) 1997, 2025, 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 *
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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 *
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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23 */
24
25 #ifndef SHARE_OOPS_KLASS_HPP
26 #define SHARE_OOPS_KLASS_HPP
27
28 #include "oops/klassFlags.hpp"
29 #include "oops/markWord.hpp"
30 #include "oops/metadata.hpp"
31 #include "oops/oop.hpp"
32 #include "oops/oopHandle.hpp"
33 #include "utilities/accessFlags.hpp"
34 #include "utilities/macros.hpp"
35 #if INCLUDE_JFR
36 #include "jfr/support/jfrTraceIdExtension.hpp"
37 #endif
38
39 //
40 // A Klass provides:
41 // 1: language level class object (method dictionary etc.)
42 // 2: provide vm dispatch behavior for the object
43 // Both functions are combined into one C++ class.
44
45 // One reason for the oop/klass dichotomy in the implementation is
46 // that we don't want a C++ vtbl pointer in every object. Thus,
47 // normal oops don't have any virtual functions. Instead, they
48 // forward all "virtual" functions to their klass, which does have
49 // a vtbl and does the C++ dispatch depending on the object's
50 // actual type. (See oop.inline.hpp for some of the forwarding code.)
51 // ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"!
52
53 // Forward declarations.
54 template <class T> class Array;
55 template <class T> class GrowableArray;
56 class ClassLoaderData;
57 class fieldDescriptor;
58 class klassVtable;
59 class ModuleEntry;
60 class PackageEntry;
61 class vtableEntry;
62
63 class Klass : public Metadata {
64
65 friend class VMStructs;
66 friend class JVMCIVMStructs;
67 public:
68 // Klass Kinds for all subclasses of Klass
69 enum KlassKind : u2 {
70 InstanceKlassKind,
71 InstanceRefKlassKind,
72 InstanceMirrorKlassKind,
73 InstanceClassLoaderKlassKind,
74 InstanceStackChunkKlassKind,
75 TypeArrayKlassKind,
76 ObjArrayKlassKind,
77 UnknownKlassKind
78 };
79
80 static const uint KLASS_KIND_COUNT = ObjArrayKlassKind + 1;
81 protected:
82
83 // If you add a new field that points to any metaspace object, you
84 // must add this field to Klass::metaspace_pointers_do().
85
86 // note: put frequently-used fields together at start of klass structure
87 // for better cache behavior (may not make much of a difference but sure won't hurt)
88 enum { _primary_super_limit = 8 };
89
90 // The "layout helper" is a combined descriptor of object layout.
91 // For klasses which are neither instance nor array, the value is zero.
92 //
93 // For instances, layout helper is a positive number, the instance size.
94 // This size is already passed through align_object_size and scaled to bytes.
95 // The low order bit is set if instances of this class cannot be
96 // allocated using the fastpath.
97 //
98 // For arrays, layout helper is a negative number, containing four
99 // distinct bytes, as follows:
100 // MSB:[tag, hsz, ebt, log2(esz)]:LSB
101 // where:
102 // tag is 0x80 if the elements are oops, 0xC0 if non-oops
103 // hsz is array header size in bytes (i.e., offset of first element)
104 // ebt is the BasicType of the elements
105 // esz is the element size in bytes
106 // This packed word is arranged so as to be quickly unpacked by the
107 // various fast paths that use the various subfields.
108 //
109 // The esz bits can be used directly by a SLL instruction, without masking.
110 //
111 // Note that the array-kind tag looks like 0x00 for instance klasses,
112 // since their length in bytes is always less than 24Mb.
113 //
114 // Final note: This comes first, immediately after C++ vtable,
115 // because it is frequently queried.
116 jint _layout_helper;
117
118 // Klass kind used to resolve the runtime type of the instance.
119 // - Used to implement devirtualized oop closure dispatching.
120 // - Various type checking in the JVM
121 const KlassKind _kind;
122
123 AccessFlags _access_flags; // Access flags. The class/interface distinction is stored here.
124 // Some flags created by the JVM, not in the class file itself,
125 // are in _misc_flags below.
126 KlassFlags _misc_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 markWord _prototype_header; // Used to initialize objects' header
163
164 // Bitmap and hash code used by hashed secondary supers.
165 uintx _secondary_supers_bitmap;
166 uint8_t _hash_slot;
167
168 private:
169 // This is an index into AOTClassLocationConfig::class_locations(), to
170 // indicate the AOTClassLocation where this class is loaded from during
171 // dump time. If a class is not loaded from the AOT cache, this field is
172 // -1.
173 s2 _shared_class_path_index;
174
175 #if INCLUDE_CDS
176 // Various attributes for shared classes. Should be zero for a non-shared class.
177 u2 _shared_class_flags;
178 enum CDSSharedClassFlags {
179 _is_shared_class = 1 << 0, // shadows MetaspaceObj::is_shared
180 _archived_lambda_proxy_is_available = 1 << 1,
181 _has_value_based_class_annotation = 1 << 2,
182 _verified_at_dump_time = 1 << 3,
183 _has_archived_enum_objs = 1 << 4,
184 // This class was not loaded from a classfile in the module image
185 // or classpath.
186 _is_generated_shared_class = 1 << 5,
187 // archived mirror already initialized by AOT-cache assembly: no further need to call <clinit>
188 _has_aot_initialized_mirror = 1 << 6,
189 };
190 #endif
191
192 int _vtable_len; // vtable length. This field may be read very often when we
193 // have lots of itable dispatches (e.g., lambdas and streams).
194 // Keep it away from the beginning of a Klass to avoid cacheline
195 // contention that may happen when a nearby object is modified.
196
197 CDS_JAVA_HEAP_ONLY(int _archived_mirror_index;)
198
199 public:
200
201 JFR_ONLY(DEFINE_TRACE_ID_FIELD;)
202
203 protected:
204
205 Klass(KlassKind kind);
206 Klass();
207
208 public:
209 int kind() { return _kind; }
210
211 enum class DefaultsLookupMode { find, skip };
212 enum class OverpassLookupMode { find, skip };
213 enum class StaticLookupMode { find, skip };
214 enum class PrivateLookupMode { find, skip };
215
216 virtual bool is_klass() const { return true; }
217
218 // super() cannot be InstanceKlass* -- Java arrays are covariant, and _super is used
219 // to implement that. NB: the _super of "[Ljava/lang/Integer;" is "[Ljava/lang/Number;"
220 // If this is not what your code expects, you're probably looking for Klass::java_super().
221 Klass* super() const { return _super; }
222 void set_super(Klass* k) { _super = k; }
223
224 // initializes _super link, _primary_supers & _secondary_supers arrays
225 void initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS);
226
227 // klass-specific helper for initializing _secondary_supers
228 virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots,
229 Array<InstanceKlass*>* transitive_interfaces);
230
231 // java_super is the Java-level super type as specified by Class.getSuperClass.
232 virtual InstanceKlass* java_super() const { return nullptr; }
233
234 juint super_check_offset() const { return _super_check_offset; }
235 void set_super_check_offset(juint o) { _super_check_offset = o; }
236
237 Klass* secondary_super_cache() const { return _secondary_super_cache; }
238 void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; }
239
240 Array<Klass*>* secondary_supers() const { return _secondary_supers; }
241 void set_secondary_supers(Array<Klass*>* k, uintx bitmap);
242
243 uint8_t hash_slot() const { return _hash_slot; }
244
245 // Return the element of the _super chain of the given depth.
246 // If there is no such element, return either null or this.
247 Klass* primary_super_of_depth(juint i) const {
248 assert(i < primary_super_limit(), "oob");
249 Klass* super = _primary_supers[i];
250 assert(super == nullptr || super->super_depth() == i, "correct display");
251 return super;
252 }
253
254 // Can this klass be a primary super? False for interfaces and arrays of
255 // interfaces. False also for arrays or classes with long super chains.
256 bool can_be_primary_super() const {
257 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
258 return super_check_offset() != secondary_offset;
259 }
260 virtual bool can_be_primary_super_slow() const;
261
262 // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit].
263 juint super_depth() const {
264 if (!can_be_primary_super()) {
265 return primary_super_limit();
266 } else {
267 juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*);
268 assert(d < primary_super_limit(), "oob");
269 assert(_primary_supers[d] == this, "proper init");
270 return d;
271 }
272 }
273
274 // java mirror
275 oop java_mirror() const;
276 oop java_mirror_no_keepalive() const;
277 void set_java_mirror(Handle m);
278
279 oop archived_java_mirror() NOT_CDS_JAVA_HEAP_RETURN_(nullptr);
280
281 // Temporary mirror switch used by RedefineClasses
282 OopHandle java_mirror_handle() const { return _java_mirror; }
283 void swap_java_mirror_handle(OopHandle& mirror) { _java_mirror.swap(mirror); }
284
285 // Set java mirror OopHandle to null for CDS
286 // This leaves the OopHandle in the CLD, but that's ok, you can't release them.
287 void clear_java_mirror_handle() { _java_mirror = OopHandle(); }
288
289 // size helper
290 int layout_helper() const { return _layout_helper; }
291 void set_layout_helper(int lh) { _layout_helper = lh; }
292
293 // Note: for instances layout_helper() may include padding.
294 // Use InstanceKlass::contains_field_offset to classify field offsets.
295
296 // sub/superklass links
297 Klass* subklass(bool log = false) const;
298 Klass* next_sibling(bool log = false) const;
299
300 InstanceKlass* superklass() const;
301 void append_to_sibling_list(); // add newly created receiver to superklass' subklass list
302
303 void set_next_link(Klass* k) { _next_link = k; }
304 Klass* next_link() const { return _next_link; } // The next klass defined by the class loader.
305 Klass** next_link_addr() { return &_next_link; }
306
307 // class loader data
308 ClassLoaderData* class_loader_data() const { return _class_loader_data; }
309 void set_class_loader_data(ClassLoaderData* loader_data) { _class_loader_data = loader_data; }
310
311 s2 shared_classpath_index() const {
312 return _shared_class_path_index;
313 };
314
315 void set_shared_classpath_index(s2 index) {
316 _shared_class_path_index = index;
317 };
318
319 bool has_archived_mirror_index() const {
320 CDS_JAVA_HEAP_ONLY(return _archived_mirror_index >= 0;)
321 NOT_CDS_JAVA_HEAP(return false);
322 }
323
324 void clear_archived_mirror_index() NOT_CDS_JAVA_HEAP_RETURN;
325
326 void set_lambda_proxy_is_available() {
327 CDS_ONLY(_shared_class_flags |= _archived_lambda_proxy_is_available;)
328 }
329 void clear_lambda_proxy_is_available() {
330 CDS_ONLY(_shared_class_flags &= (u2)(~_archived_lambda_proxy_is_available);)
331 }
332 bool lambda_proxy_is_available() const {
333 CDS_ONLY(return (_shared_class_flags & _archived_lambda_proxy_is_available) != 0;)
334 NOT_CDS(return false;)
335 }
336
337 void set_has_value_based_class_annotation() {
338 CDS_ONLY(_shared_class_flags |= _has_value_based_class_annotation;)
339 }
340 void clear_has_value_based_class_annotation() {
341 CDS_ONLY(_shared_class_flags &= (u2)(~_has_value_based_class_annotation);)
342 }
343 bool has_value_based_class_annotation() const {
344 CDS_ONLY(return (_shared_class_flags & _has_value_based_class_annotation) != 0;)
345 NOT_CDS(return false;)
346 }
347
348 void set_verified_at_dump_time() {
349 CDS_ONLY(_shared_class_flags |= _verified_at_dump_time;)
350 }
351 bool verified_at_dump_time() const {
352 CDS_ONLY(return (_shared_class_flags & _verified_at_dump_time) != 0;)
353 NOT_CDS(return false;)
354 }
355
356 void set_has_archived_enum_objs() {
357 CDS_ONLY(_shared_class_flags |= _has_archived_enum_objs;)
358 }
359 bool has_archived_enum_objs() const {
360 CDS_ONLY(return (_shared_class_flags & _has_archived_enum_objs) != 0;)
361 NOT_CDS(return false;)
362 }
363
364 void set_is_generated_shared_class() {
365 CDS_ONLY(_shared_class_flags |= _is_generated_shared_class;)
366 }
367 bool is_generated_shared_class() const {
368 CDS_ONLY(return (_shared_class_flags & _is_generated_shared_class) != 0;)
369 NOT_CDS(return false;)
370 }
371
372 void set_has_aot_initialized_mirror() {
373 CDS_ONLY(_shared_class_flags |= _has_aot_initialized_mirror;)
374 }
375 bool has_aot_initialized_mirror() const {
376 CDS_ONLY(return (_shared_class_flags & _has_aot_initialized_mirror) != 0;)
377 NOT_CDS(return false;)
378 }
379
380 bool is_shared() const { // shadows MetaspaceObj::is_shared)()
381 CDS_ONLY(return (_shared_class_flags & _is_shared_class) != 0;)
382 NOT_CDS(return false;)
383 }
384
385 void set_is_shared() {
386 CDS_ONLY(_shared_class_flags |= _is_shared_class;)
387 }
388
389 // Obtain the module or package for this class
390 virtual ModuleEntry* module() const = 0;
391 virtual PackageEntry* package() const = 0;
392
393 protected: // internal accessors
394 void set_subklass(Klass* s);
395 void set_next_sibling(Klass* s);
396
397 private:
398 static uint8_t compute_hash_slot(Symbol* s);
399 static void hash_insert(Klass* klass, GrowableArray<Klass*>* secondaries, uintx& bitmap);
400 static uintx hash_secondary_supers(Array<Klass*>* secondaries, bool rewrite);
401
402 bool search_secondary_supers(Klass* k) const;
403 bool lookup_secondary_supers_table(Klass *k) const;
404 bool linear_search_secondary_supers(const Klass* k) const;
405 bool fallback_search_secondary_supers(const Klass* k, int index, uintx rotated_bitmap) const;
406
407 public:
408 // Secondary supers table support
409 static Array<Klass*>* pack_secondary_supers(ClassLoaderData* loader_data,
410 GrowableArray<Klass*>* primaries,
411 GrowableArray<Klass*>* secondaries,
412 uintx& bitmap,
413 TRAPS);
414
415 static uintx compute_secondary_supers_bitmap(Array<Klass*>* secondary_supers);
416 static uint8_t compute_home_slot(Klass* k, uintx bitmap);
417
418 static constexpr int SECONDARY_SUPERS_TABLE_SIZE = sizeof(_secondary_supers_bitmap) * 8;
419 static constexpr int SECONDARY_SUPERS_TABLE_MASK = SECONDARY_SUPERS_TABLE_SIZE - 1;
420
421 static constexpr uintx SECONDARY_SUPERS_BITMAP_EMPTY = 0;
422 static constexpr uintx SECONDARY_SUPERS_BITMAP_FULL = ~(uintx)0;
423
424 // Compiler support
425 static ByteSize super_offset() { return byte_offset_of(Klass, _super); }
426 static ByteSize super_check_offset_offset() { return byte_offset_of(Klass, _super_check_offset); }
427 static ByteSize primary_supers_offset() { return byte_offset_of(Klass, _primary_supers); }
428 static ByteSize secondary_super_cache_offset() { return byte_offset_of(Klass, _secondary_super_cache); }
429 static ByteSize secondary_supers_offset() { return byte_offset_of(Klass, _secondary_supers); }
430 static ByteSize java_mirror_offset() { return byte_offset_of(Klass, _java_mirror); }
431 static ByteSize class_loader_data_offset() { return byte_offset_of(Klass, _class_loader_data); }
432 static ByteSize layout_helper_offset() { return byte_offset_of(Klass, _layout_helper); }
433 static ByteSize access_flags_offset() { return byte_offset_of(Klass, _access_flags); }
434 #if INCLUDE_JVMCI
435 static ByteSize subklass_offset() { return byte_offset_of(Klass, _subklass); }
436 static ByteSize next_sibling_offset() { return byte_offset_of(Klass, _next_sibling); }
437 #endif
438 static ByteSize secondary_supers_bitmap_offset()
439 { return byte_offset_of(Klass, _secondary_supers_bitmap); }
440 static ByteSize hash_slot_offset() { return byte_offset_of(Klass, _hash_slot); }
441 static ByteSize misc_flags_offset() { return byte_offset_of(Klass, _misc_flags._flags); }
442
443 // Unpacking layout_helper:
444 static const int _lh_neutral_value = 0; // neutral non-array non-instance value
445 static const int _lh_instance_slow_path_bit = 0x01;
446 static const int _lh_log2_element_size_shift = BitsPerByte*0;
447 static const int _lh_log2_element_size_mask = BitsPerLong-1;
448 static const int _lh_element_type_shift = BitsPerByte*1;
449 static const int _lh_element_type_mask = right_n_bits(BitsPerByte); // shifted mask
450 static const int _lh_header_size_shift = BitsPerByte*2;
451 static const int _lh_header_size_mask = right_n_bits(BitsPerByte); // shifted mask
452 static const int _lh_array_tag_bits = 2;
453 static const int _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits;
454 static const int _lh_array_tag_obj_value = ~0x01; // 0x80000000 >> 30
455
456 static const unsigned int _lh_array_tag_type_value = 0Xffffffff; // ~0x00, // 0xC0000000 >> 30
457
458 static int layout_helper_size_in_bytes(jint lh) {
459 assert(lh > (jint)_lh_neutral_value, "must be instance");
460 return (int) lh & ~_lh_instance_slow_path_bit;
461 }
462 static bool layout_helper_needs_slow_path(jint lh) {
463 assert(lh > (jint)_lh_neutral_value, "must be instance");
464 return (lh & _lh_instance_slow_path_bit) != 0;
465 }
466 static bool layout_helper_is_instance(jint lh) {
467 return (jint)lh > (jint)_lh_neutral_value;
468 }
469 static bool layout_helper_is_array(jint lh) {
470 return (jint)lh < (jint)_lh_neutral_value;
471 }
472 static bool layout_helper_is_typeArray(jint lh) {
473 // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
474 return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
475 }
476 static bool layout_helper_is_objArray(jint lh) {
477 // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
478 return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
479 }
480 static int layout_helper_header_size(jint lh) {
481 assert(lh < (jint)_lh_neutral_value, "must be array");
482 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
483 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
484 return hsize;
485 }
486 static BasicType layout_helper_element_type(jint lh) {
487 assert(lh < (jint)_lh_neutral_value, "must be array");
488 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
489 assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
490 return (BasicType) btvalue;
491 }
492
493 // Want a pattern to quickly diff against layout header in register
494 // find something less clever!
495 static int layout_helper_boolean_diffbit() {
496 jint zlh = array_layout_helper(T_BOOLEAN);
497 jint blh = array_layout_helper(T_BYTE);
498 assert(zlh != blh, "array layout helpers must differ");
499 int diffbit = 1;
500 while ((diffbit & (zlh ^ blh)) == 0 && (diffbit & zlh) == 0) {
501 diffbit <<= 1;
502 assert(diffbit != 0, "make sure T_BOOLEAN has a different bit than T_BYTE");
503 }
504 return diffbit;
505 }
506
507 static int layout_helper_log2_element_size(jint lh) {
508 assert(lh < (jint)_lh_neutral_value, "must be array");
509 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
510 assert(l2esz <= LogBytesPerLong,
511 "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh);
512 return l2esz;
513 }
514 static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
515 return (tag << _lh_array_tag_shift)
516 | (hsize << _lh_header_size_shift)
517 | ((int)etype << _lh_element_type_shift)
518 | (log2_esize << _lh_log2_element_size_shift);
519 }
520 static jint instance_layout_helper(jint size, bool slow_path_flag) {
521 return (size << LogBytesPerWord)
522 | (slow_path_flag ? _lh_instance_slow_path_bit : 0);
523 }
524 static int layout_helper_to_size_helper(jint lh) {
525 assert(lh > (jint)_lh_neutral_value, "must be instance");
526 // Note that the following expression discards _lh_instance_slow_path_bit.
527 return lh >> LogBytesPerWord;
528 }
529 // Out-of-line version computes everything based on the etype:
530 static jint array_layout_helper(BasicType etype);
531
532 // What is the maximum number of primary superclasses any klass can have?
533 static juint primary_super_limit() { return _primary_super_limit; }
534
535 // vtables
536 klassVtable vtable() const;
537 int vtable_length() const { return _vtable_len; }
538
539 // subclass check
540 bool is_subclass_of(const Klass* k) const;
541
542 // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
543 bool is_subtype_of(Klass* k) const;
544
545 public:
546 // Find LCA in class hierarchy
547 Klass *LCA( Klass *k );
548
549 // Check whether reflection/jni/jvm code is allowed to instantiate this class;
550 // if not, throw either an Error or an Exception.
551 virtual void check_valid_for_instantiation(bool throwError, TRAPS);
552
553 // array copying
554 virtual void copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
555
556 // tells if the class should be initialized
557 virtual bool should_be_initialized() const { return false; }
558 // initializes the klass
559 virtual void initialize(TRAPS);
560 virtual Klass* find_field(Symbol* name, Symbol* signature, fieldDescriptor* fd) const;
561 virtual Method* uncached_lookup_method(const Symbol* name, const Symbol* signature,
562 OverpassLookupMode overpass_mode,
563 PrivateLookupMode = PrivateLookupMode::find) const;
564 public:
565 Method* lookup_method(const Symbol* name, const Symbol* signature) const {
566 return uncached_lookup_method(name, signature, OverpassLookupMode::find);
567 }
568
569 // array class with specific rank
570 virtual ArrayKlass* array_klass(int rank, TRAPS) = 0;
571
572 // array class with this klass as element type
573 virtual ArrayKlass* array_klass(TRAPS) = 0;
574
575 // These will return null instead of allocating on the heap:
576 virtual ArrayKlass* array_klass_or_null(int rank) = 0;
577 virtual ArrayKlass* array_klass_or_null() = 0;
578
579 virtual oop protection_domain() const = 0;
580
581 oop class_loader() const;
582
583 inline oop klass_holder() const;
584
585 inline void keep_alive() const;
586
587 protected:
588
589 // Error handling when length > max_length or length < 0
590 static void check_array_allocation_length(int length, int max_length, TRAPS);
591
592 void set_vtable_length(int len) { _vtable_len= len; }
593
594 vtableEntry* start_of_vtable() const;
595 #if INCLUDE_CDS
596 void restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS);
597 #endif
598 public:
599 Method* method_at_vtable(int index);
600
601 static ByteSize vtable_start_offset();
602 static ByteSize vtable_length_offset() {
603 return byte_offset_of(Klass, _vtable_len);
604 }
605
606 #if INCLUDE_CDS
607 // CDS support - remove and restore oops from metadata. Oops are not shared.
608 virtual void remove_unshareable_info();
609 virtual void remove_java_mirror();
610
611 bool is_unshareable_info_restored() const {
612 assert(is_shared(), "use this for shared classes only");
613 if (has_archived_mirror_index()) {
614 // _java_mirror is not a valid OopHandle but rather an encoded reference in the shared heap
615 return false;
616 } else if (_java_mirror.is_empty()) {
617 return false;
618 } else {
619 return true;
620 }
621 }
622 #endif // INCLUDE_CDS
623
624 public:
625 // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
626 // These functions describe behavior for the oop not the KLASS.
627
628 // actual oop size of obj in memory in word size.
629 virtual size_t oop_size(oop obj) const = 0;
630
631 // Size of klass in word size.
632 virtual int size() const = 0;
633
634 // Returns the Java name for a class (Resource allocated)
635 // For arrays, this returns the name of the element with a leading '['.
636 // For classes, this returns the name with the package separators
637 // turned into '.'s.
638 const char* external_name() const;
639 // Returns the name for a class (Resource allocated) as the class
640 // would appear in a signature.
641 // For arrays, this returns the name of the element with a leading '['.
642 // For classes, this returns the name with a leading 'L' and a trailing ';'
643 // and the package separators as '/'.
644 virtual const char* signature_name() const;
645
646 const char* joint_in_module_of_loader(const Klass* class2, bool include_parent_loader = false) const;
647 const char* class_in_module_of_loader(bool use_are = false, bool include_parent_loader = false) const;
648
649 // Returns "interface", "abstract class" or "class".
650 const char* external_kind() const;
651
652 // type testing operations
653 #ifdef ASSERT
654 protected:
655 virtual bool is_instance_klass_slow() const { return false; }
656 virtual bool is_array_klass_slow() const { return false; }
657 virtual bool is_objArray_klass_slow() const { return false; }
658 virtual bool is_typeArray_klass_slow() const { return false; }
659 #endif // ASSERT
660 public:
661
662 // Fast non-virtual versions
663 #ifndef ASSERT
664 #define assert_same_query(xval, xcheck) xval
665 #else
666 private:
667 static bool assert_same_query(bool xval, bool xslow) {
668 assert(xval == xslow, "slow and fast queries agree");
669 return xval;
670 }
671 public:
672 #endif
673
674 bool is_instance_klass() const { return assert_same_query(_kind <= InstanceStackChunkKlassKind, is_instance_klass_slow()); }
675 // Other is anything that is not one of the more specialized kinds of InstanceKlass.
676 bool is_other_instance_klass() const { return _kind == InstanceKlassKind; }
677 bool is_reference_instance_klass() const { return _kind == InstanceRefKlassKind; }
678 bool is_mirror_instance_klass() const { return _kind == InstanceMirrorKlassKind; }
679 bool is_class_loader_instance_klass() const { return _kind == InstanceClassLoaderKlassKind; }
680 bool is_array_klass() const { return assert_same_query( _kind >= TypeArrayKlassKind, is_array_klass_slow()); }
681 bool is_stack_chunk_instance_klass() const { return _kind == InstanceStackChunkKlassKind; }
682 bool is_objArray_klass() const { return assert_same_query( _kind == ObjArrayKlassKind, is_objArray_klass_slow()); }
683 bool is_typeArray_klass() const { return assert_same_query( _kind == TypeArrayKlassKind, is_typeArray_klass_slow()); }
684 #undef assert_same_query
685
686 // Access flags
687 AccessFlags access_flags() const { return _access_flags; }
688 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
689
690 bool is_public() const { return _access_flags.is_public(); }
691 bool is_final() const { return _access_flags.is_final(); }
692 bool is_interface() const { return _access_flags.is_interface(); }
693 bool is_abstract() const { return _access_flags.is_abstract(); }
694 bool is_super() const { return _access_flags.is_super(); }
695 bool is_synthetic() const { return _access_flags.is_synthetic(); }
696 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
697 bool has_finalizer() const { return _misc_flags.has_finalizer(); }
698 void set_has_finalizer() { _misc_flags.set_has_finalizer(true); }
699 bool is_hidden() const { return _misc_flags.is_hidden_class(); }
700 void set_is_hidden() { _misc_flags.set_is_hidden_class(true); }
701 bool is_value_based() const { return _misc_flags.is_value_based_class(); }
702 void set_is_value_based() { _misc_flags.set_is_value_based_class(true); }
703
704 klass_flags_t misc_flags() const { return _misc_flags.value(); }
705
706 inline bool is_non_strong_hidden() const;
707
708 bool is_cloneable() const;
709 void set_is_cloneable();
710
711 inline markWord prototype_header() const;
712 inline void set_prototype_header(markWord header);
713 static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); }
714
715 JFR_ONLY(DEFINE_TRACE_ID_METHODS;)
716
717 virtual void metaspace_pointers_do(MetaspaceClosure* iter);
718 virtual MetaspaceObj::Type type() const { return ClassType; }
719
720 inline bool is_loader_alive() const;
721 inline bool is_loader_present_and_alive() const;
722
723 void clean_subklass();
724
725 // Clean out unnecessary weak klass links from the whole klass hierarchy.
726 static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true);
727 // Clean out unnecessary weak klass links from the given InstanceKlass.
728 static void clean_weak_instanceklass_links(InstanceKlass* ik);
729
730 // Return self, except for abstract classes with exactly 1
731 // implementor. Then return the 1 concrete implementation.
732 Klass *up_cast_abstract();
733
734 // klass name
735 Symbol* name() const { return _name; }
736 void set_name(Symbol* n);
737
738 virtual void release_C_heap_structures(bool release_constant_pool = true);
739
740 public:
741 // Get modifier flags from Java mirror cache.
742 int modifier_flags() const;
743
744 // Compute modifier flags from the original data. This also allows
745 // accessing flags when Java mirror is already dead, e.g. during class
746 // unloading.
747 virtual u2 compute_modifier_flags() const = 0;
748
749 // JVMTI support
750 virtual jint jvmti_class_status() const;
751
752 // Printing
753 virtual void print_on(outputStream* st) const;
754
755 virtual void oop_print_value_on(oop obj, outputStream* st);
756 virtual void oop_print_on (oop obj, outputStream* st);
757
758 void print_secondary_supers_on(outputStream* st) const;
759
760 virtual const char* internal_name() const = 0;
761
762 // Verification
763 virtual void verify_on(outputStream* st);
764 void verify() { verify_on(tty); }
765
766 #ifndef PRODUCT
767 bool verify_vtable_index(int index);
768 #endif
769
770 virtual void oop_verify_on(oop obj, outputStream* st);
771
772 // for error reporting
773 static bool is_valid(Klass* k);
774
775 static void on_secondary_supers_verification_failure(Klass* super, Klass* sub, bool linear_result, bool table_result, const char* msg);
776
777 // Returns true if this Klass needs to be addressable via narrow Klass ID.
778 inline bool needs_narrow_id() const;
779
780 };
781
782 #endif // SHARE_OOPS_KLASS_HPP