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
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7 * published by the Free Software Foundation.
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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).
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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 _aot_class_flags;
178 enum {
179 _in_aot_cache = 1 << 0,
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 _is_aot_generated_class = 1 << 5, // this class was not loaded from a classfile in the module image
185 // or classpath, but was generated during AOT cache assembly.
186 _has_aot_initialized_mirror = 1 << 6, // archived mirror already initialized by AOT cache assembly.
187 // no further need to call <clinit>
188 _has_aot_safe_initializer = 1 << 7, // has @AOTSafeClassInitializer annotation
189 _is_runtime_setup_required = 1 << 8, // has a runtimeSetup method to be called when
190 // this class is loaded from AOT cache
191 };
192 #endif
193
194 int _vtable_len; // vtable length. This field may be read very often when we
195 // have lots of itable dispatches (e.g., lambdas and streams).
196 // Keep it away from the beginning of a Klass to avoid cacheline
197 // contention that may happen when a nearby object is modified.
198
199 CDS_JAVA_HEAP_ONLY(int _archived_mirror_index;)
200
201 public:
202
203 JFR_ONLY(DEFINE_TRACE_ID_FIELD;)
204
205 protected:
206
207 Klass(KlassKind kind);
208 Klass();
209
210 public:
211 int kind() { return _kind; }
212
213 enum class DefaultsLookupMode { find, skip };
214 enum class OverpassLookupMode { find, skip };
215 enum class StaticLookupMode { find, skip };
216 enum class PrivateLookupMode { find, skip };
217
218 virtual bool is_klass() const { return true; }
219
220 // super() cannot be InstanceKlass* -- Java arrays are covariant, and _super is used
221 // to implement that. NB: the _super of "[Ljava/lang/Integer;" is "[Ljava/lang/Number;"
222 // If this is not what your code expects, you're probably looking for:
223 // - Klass::java_super() - if you have a Klass*
224 // - InstanceKlass::super() - if you have an InstanceKlass* ik, ik->super() returns InstanceKlass*.
225 Klass* super() const { return _super; }
226 void set_super(Klass* k) { _super = k; }
227
228 // initializes _super link, _primary_supers & _secondary_supers arrays
229 void initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS);
230
231 // klass-specific helper for initializing _secondary_supers
232 virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots,
233 Array<InstanceKlass*>* transitive_interfaces);
234
235 // java_super is the Java-level super type as specified by Class.getSuperClass.
236 virtual InstanceKlass* java_super() const { return nullptr; }
237
238 juint super_check_offset() const { return _super_check_offset; }
239 void set_super_check_offset(juint o) { _super_check_offset = o; }
240
241 Klass* secondary_super_cache() const { return _secondary_super_cache; }
242 void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; }
243
244 Array<Klass*>* secondary_supers() const { return _secondary_supers; }
245 void set_secondary_supers(Array<Klass*>* k, uintx bitmap);
246
247 uint8_t hash_slot() const { return _hash_slot; }
248
249 // Return the element of the _super chain of the given depth.
250 // If there is no such element, return either null or this.
251 Klass* primary_super_of_depth(juint i) const {
252 assert(i < primary_super_limit(), "oob");
253 Klass* super = _primary_supers[i];
254 assert(super == nullptr || super->super_depth() == i, "correct display");
255 return super;
256 }
257
258 // Can this klass be a primary super? False for interfaces and arrays of
259 // interfaces. False also for arrays or classes with long super chains.
260 bool can_be_primary_super() const {
261 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
262 return super_check_offset() != secondary_offset;
263 }
264 virtual bool can_be_primary_super_slow() const;
265
266 // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit].
267 juint super_depth() const {
268 if (!can_be_primary_super()) {
269 return primary_super_limit();
270 } else {
271 juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*);
272 assert(d < primary_super_limit(), "oob");
273 assert(_primary_supers[d] == this, "proper init");
274 return d;
275 }
276 }
277
278 // java mirror
279 oop java_mirror() const;
280 oop java_mirror_no_keepalive() const;
281 void set_java_mirror(Handle m);
282
283 oop archived_java_mirror() NOT_CDS_JAVA_HEAP_RETURN_(nullptr);
284
285 // Temporary mirror switch used by RedefineClasses
286 OopHandle java_mirror_handle() const { return _java_mirror; }
287 void swap_java_mirror_handle(OopHandle& mirror) { _java_mirror.swap(mirror); }
288
289 // Set java mirror OopHandle to null for CDS
290 // This leaves the OopHandle in the CLD, but that's ok, you can't release them.
291 void clear_java_mirror_handle() { _java_mirror = OopHandle(); }
292
293 // size helper
294 int layout_helper() const { return _layout_helper; }
295 void set_layout_helper(int lh) { _layout_helper = lh; }
296
297 // Note: for instances layout_helper() may include padding.
298 // Use InstanceKlass::contains_field_offset to classify field offsets.
299
300 // sub/superklass links
301 Klass* subklass(bool log = false) const;
302 Klass* next_sibling(bool log = false) const;
303
304 void append_to_sibling_list(); // add newly created receiver to superklass' subklass list
305
306 void set_next_link(Klass* k) { _next_link = k; }
307 Klass* next_link() const { return _next_link; } // The next klass defined by the class loader.
308 Klass** next_link_addr() { return &_next_link; }
309
310 // class loader data
311 ClassLoaderData* class_loader_data() const { return _class_loader_data; }
312 void set_class_loader_data(ClassLoaderData* loader_data) { _class_loader_data = loader_data; }
313
314 s2 shared_classpath_index() const {
315 return _shared_class_path_index;
316 };
317
318 void set_shared_classpath_index(s2 index) {
319 _shared_class_path_index = index;
320 };
321
322 bool has_archived_mirror_index() const {
323 CDS_JAVA_HEAP_ONLY(return _archived_mirror_index >= 0;)
324 NOT_CDS_JAVA_HEAP(return false);
325 }
326
327 void clear_archived_mirror_index() NOT_CDS_JAVA_HEAP_RETURN;
328
329 void set_lambda_proxy_is_available() {
330 CDS_ONLY(_aot_class_flags |= _archived_lambda_proxy_is_available;)
331 }
332 void clear_lambda_proxy_is_available() {
333 CDS_ONLY(_aot_class_flags &= (u2)(~_archived_lambda_proxy_is_available);)
334 }
335 bool lambda_proxy_is_available() const {
336 CDS_ONLY(return (_aot_class_flags & _archived_lambda_proxy_is_available) != 0;)
337 NOT_CDS(return false;)
338 }
339
340 void set_has_value_based_class_annotation() {
341 CDS_ONLY(_aot_class_flags |= _has_value_based_class_annotation;)
342 }
343 void clear_has_value_based_class_annotation() {
344 CDS_ONLY(_aot_class_flags &= (u2)(~_has_value_based_class_annotation);)
345 }
346 bool has_value_based_class_annotation() const {
347 CDS_ONLY(return (_aot_class_flags & _has_value_based_class_annotation) != 0;)
348 NOT_CDS(return false;)
349 }
350
351 void set_verified_at_dump_time() {
352 CDS_ONLY(_aot_class_flags |= _verified_at_dump_time;)
353 }
354 bool verified_at_dump_time() const {
355 CDS_ONLY(return (_aot_class_flags & _verified_at_dump_time) != 0;)
356 NOT_CDS(return false;)
357 }
358
359 void set_has_archived_enum_objs() {
360 CDS_ONLY(_aot_class_flags |= _has_archived_enum_objs;)
361 }
362 bool has_archived_enum_objs() const {
363 CDS_ONLY(return (_aot_class_flags & _has_archived_enum_objs) != 0;)
364 NOT_CDS(return false;)
365 }
366
367 void set_is_aot_generated_class() {
368 CDS_ONLY(_aot_class_flags |= _is_aot_generated_class;)
369 }
370 bool is_aot_generated_class() const {
371 CDS_ONLY(return (_aot_class_flags & _is_aot_generated_class) != 0;)
372 NOT_CDS(return false;)
373 }
374
375 void set_has_aot_initialized_mirror() {
376 CDS_ONLY(_aot_class_flags |= _has_aot_initialized_mirror;)
377 }
378 bool has_aot_initialized_mirror() const {
379 CDS_ONLY(return (_aot_class_flags & _has_aot_initialized_mirror) != 0;)
380 NOT_CDS(return false;)
381 }
382
383 // Indicates presence of @AOTSafeClassInitializer. Also see AOTClassInitializer for more details.
384 void set_has_aot_safe_initializer() {
385 CDS_ONLY(_aot_class_flags |= _has_aot_safe_initializer;)
386 }
387 bool has_aot_safe_initializer() const {
388 CDS_ONLY(return (_aot_class_flags & _has_aot_safe_initializer) != 0;)
389 NOT_CDS(return false;)
390 }
391
392 // Indicates @AOTRuntimeSetup private static void runtimeSetup() presence.
393 void set_is_runtime_setup_required() {
394 CDS_ONLY(_aot_class_flags |= _is_runtime_setup_required;)
395 }
396 bool is_runtime_setup_required() const {
397 CDS_ONLY(return (_aot_class_flags & _is_runtime_setup_required) != 0;)
398 NOT_CDS(return false;)
399 }
400
401 bool in_aot_cache() const { // shadows MetaspaceObj::in_aot_cache)()
402 CDS_ONLY(return (_aot_class_flags & _in_aot_cache) != 0;)
403 NOT_CDS(return false;)
404 }
405
406 void set_in_aot_cache() {
407 CDS_ONLY(_aot_class_flags |= _in_aot_cache;)
408 }
409
410 // Obtain the module or package for this class
411 virtual ModuleEntry* module() const = 0;
412 virtual PackageEntry* package() const = 0;
413
414 protected: // internal accessors
415 void set_subklass(Klass* s);
416 void set_next_sibling(Klass* s);
417
418 private:
419 static uint8_t compute_hash_slot(Symbol* s);
420 static void hash_insert(Klass* klass, GrowableArray<Klass*>* secondaries, uintx& bitmap);
421 static uintx hash_secondary_supers(Array<Klass*>* secondaries, bool rewrite);
422
423 bool search_secondary_supers(Klass* k) const;
424 bool lookup_secondary_supers_table(Klass *k) const;
425 bool linear_search_secondary_supers(const Klass* k) const;
426 bool fallback_search_secondary_supers(const Klass* k, int index, uintx rotated_bitmap) const;
427
428 public:
429 // Secondary supers table support
430 static Array<Klass*>* pack_secondary_supers(ClassLoaderData* loader_data,
431 GrowableArray<Klass*>* primaries,
432 GrowableArray<Klass*>* secondaries,
433 uintx& bitmap,
434 TRAPS);
435
436 static uintx compute_secondary_supers_bitmap(Array<Klass*>* secondary_supers);
437 static uint8_t compute_home_slot(Klass* k, uintx bitmap);
438
439 static constexpr int SECONDARY_SUPERS_TABLE_SIZE = sizeof(_secondary_supers_bitmap) * 8;
440 static constexpr int SECONDARY_SUPERS_TABLE_MASK = SECONDARY_SUPERS_TABLE_SIZE - 1;
441
442 static constexpr uintx SECONDARY_SUPERS_BITMAP_EMPTY = 0;
443 static constexpr uintx SECONDARY_SUPERS_BITMAP_FULL = ~(uintx)0;
444
445 // Compiler support
446 static ByteSize super_offset() { return byte_offset_of(Klass, _super); }
447 static ByteSize super_check_offset_offset() { return byte_offset_of(Klass, _super_check_offset); }
448 static ByteSize primary_supers_offset() { return byte_offset_of(Klass, _primary_supers); }
449 static ByteSize secondary_super_cache_offset() { return byte_offset_of(Klass, _secondary_super_cache); }
450 static ByteSize secondary_supers_offset() { return byte_offset_of(Klass, _secondary_supers); }
451 static ByteSize java_mirror_offset() { return byte_offset_of(Klass, _java_mirror); }
452 static ByteSize class_loader_data_offset() { return byte_offset_of(Klass, _class_loader_data); }
453 static ByteSize layout_helper_offset() { return byte_offset_of(Klass, _layout_helper); }
454 static ByteSize access_flags_offset() { return byte_offset_of(Klass, _access_flags); }
455 #if INCLUDE_JVMCI
456 static ByteSize subklass_offset() { return byte_offset_of(Klass, _subklass); }
457 static ByteSize next_sibling_offset() { return byte_offset_of(Klass, _next_sibling); }
458 #endif
459 static ByteSize secondary_supers_bitmap_offset()
460 { return byte_offset_of(Klass, _secondary_supers_bitmap); }
461 static ByteSize hash_slot_offset() { return byte_offset_of(Klass, _hash_slot); }
462 static ByteSize misc_flags_offset() { return byte_offset_of(Klass, _misc_flags._flags); }
463
464 // Unpacking layout_helper:
465 static const int _lh_neutral_value = 0; // neutral non-array non-instance value
466 static const int _lh_instance_slow_path_bit = 0x01;
467 static const int _lh_log2_element_size_shift = BitsPerByte*0;
468 static const int _lh_log2_element_size_mask = BitsPerLong-1;
469 static const int _lh_element_type_shift = BitsPerByte*1;
470 static const int _lh_element_type_mask = right_n_bits(BitsPerByte); // shifted mask
471 static const int _lh_header_size_shift = BitsPerByte*2;
472 static const int _lh_header_size_mask = right_n_bits(BitsPerByte); // shifted mask
473 static const int _lh_array_tag_bits = 2;
474 static const int _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits;
475 static const int _lh_array_tag_obj_value = ~0x01; // 0x80000000 >> 30
476
477 static const unsigned int _lh_array_tag_type_value = 0Xffffffff; // ~0x00, // 0xC0000000 >> 30
478
479 static int layout_helper_size_in_bytes(jint lh) {
480 assert(lh > (jint)_lh_neutral_value, "must be instance");
481 return (int) lh & ~_lh_instance_slow_path_bit;
482 }
483 static bool layout_helper_needs_slow_path(jint lh) {
484 assert(lh > (jint)_lh_neutral_value, "must be instance");
485 return (lh & _lh_instance_slow_path_bit) != 0;
486 }
487 static bool layout_helper_is_instance(jint lh) {
488 return (jint)lh > (jint)_lh_neutral_value;
489 }
490 static bool layout_helper_is_array(jint lh) {
491 return (jint)lh < (jint)_lh_neutral_value;
492 }
493 static bool layout_helper_is_typeArray(jint lh) {
494 // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
495 return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
496 }
497 static bool layout_helper_is_objArray(jint lh) {
498 // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
499 return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
500 }
501 static int layout_helper_header_size(jint lh) {
502 assert(lh < (jint)_lh_neutral_value, "must be array");
503 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
504 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
505 return hsize;
506 }
507 static BasicType layout_helper_element_type(jint lh) {
508 assert(lh < (jint)_lh_neutral_value, "must be array");
509 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
510 assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
511 return (BasicType) btvalue;
512 }
513
514 // Want a pattern to quickly diff against layout header in register
515 // find something less clever!
516 static int layout_helper_boolean_diffbit() {
517 jint zlh = array_layout_helper(T_BOOLEAN);
518 jint blh = array_layout_helper(T_BYTE);
519 assert(zlh != blh, "array layout helpers must differ");
520 int diffbit = 1;
521 while ((diffbit & (zlh ^ blh)) == 0 && (diffbit & zlh) == 0) {
522 diffbit <<= 1;
523 assert(diffbit != 0, "make sure T_BOOLEAN has a different bit than T_BYTE");
524 }
525 return diffbit;
526 }
527
528 static int layout_helper_log2_element_size(jint lh) {
529 assert(lh < (jint)_lh_neutral_value, "must be array");
530 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
531 assert(l2esz <= LogBytesPerLong,
532 "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh);
533 return l2esz;
534 }
535 static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
536 return (tag << _lh_array_tag_shift)
537 | (hsize << _lh_header_size_shift)
538 | ((int)etype << _lh_element_type_shift)
539 | (log2_esize << _lh_log2_element_size_shift);
540 }
541 static jint instance_layout_helper(jint size, bool slow_path_flag) {
542 return (size << LogBytesPerWord)
543 | (slow_path_flag ? _lh_instance_slow_path_bit : 0);
544 }
545 static int layout_helper_to_size_helper(jint lh) {
546 assert(lh > (jint)_lh_neutral_value, "must be instance");
547 // Note that the following expression discards _lh_instance_slow_path_bit.
548 return lh >> LogBytesPerWord;
549 }
550 // Out-of-line version computes everything based on the etype:
551 static jint array_layout_helper(BasicType etype);
552
553 // What is the maximum number of primary superclasses any klass can have?
554 static juint primary_super_limit() { return _primary_super_limit; }
555
556 // vtables
557 klassVtable vtable() const;
558 int vtable_length() const { return _vtable_len; }
559
560 // subclass check
561 bool is_subclass_of(const Klass* k) const;
562
563 // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
564 bool is_subtype_of(Klass* k) const;
565
566 public:
567 // Find LCA in class hierarchy
568 Klass *LCA( Klass *k );
569
570 // Check whether reflection/jni/jvm code is allowed to instantiate this class;
571 // if not, throw either an Error or an Exception.
572 virtual void check_valid_for_instantiation(bool throwError, TRAPS);
573
574 // array copying
575 virtual void copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
576
577 // tells if the class should be initialized
578 virtual bool should_be_initialized() const { return false; }
579 // initializes the klass
580 virtual void initialize(TRAPS);
581 virtual void initialize_preemptable(TRAPS);
582 virtual Klass* find_field(Symbol* name, Symbol* signature, fieldDescriptor* fd) const;
583 virtual Method* uncached_lookup_method(const Symbol* name, const Symbol* signature,
584 OverpassLookupMode overpass_mode,
585 PrivateLookupMode = PrivateLookupMode::find) const;
586 public:
587 Method* lookup_method(const Symbol* name, const Symbol* signature) const {
588 return uncached_lookup_method(name, signature, OverpassLookupMode::find);
589 }
590
591 // array class with specific rank
592 virtual ArrayKlass* array_klass(int rank, TRAPS) = 0;
593
594 // array class with this klass as element type
595 virtual ArrayKlass* array_klass(TRAPS) = 0;
596
597 // These will return null instead of allocating on the heap:
598 virtual ArrayKlass* array_klass_or_null(int rank) = 0;
599 virtual ArrayKlass* array_klass_or_null() = 0;
600
601 virtual oop protection_domain() const = 0;
602
603 oop class_loader() const;
604
605 inline oop klass_holder() const;
606
607 inline void keep_alive() const;
608
609 protected:
610
611 // Error handling when length > max_length or length < 0
612 static void check_array_allocation_length(int length, int max_length, TRAPS);
613
614 void set_vtable_length(int len) { _vtable_len= len; }
615
616 vtableEntry* start_of_vtable() const;
617 #if INCLUDE_CDS
618 void restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS);
619 #endif
620 public:
621 Method* method_at_vtable(int index);
622
623 static ByteSize vtable_start_offset();
624 static ByteSize vtable_length_offset() {
625 return byte_offset_of(Klass, _vtable_len);
626 }
627
628 #if INCLUDE_CDS
629 // CDS support - remove and restore oops from metadata. Oops are not shared.
630 virtual void remove_unshareable_info();
631 virtual void remove_java_mirror();
632
633 bool is_unshareable_info_restored() const {
634 assert(in_aot_cache(), "use this for shared classes only");
635 if (has_archived_mirror_index()) {
636 // _java_mirror is not a valid OopHandle but rather an encoded reference in the shared heap
637 return false;
638 } else if (_java_mirror.is_empty()) {
639 return false;
640 } else {
641 return true;
642 }
643 }
644 #endif // INCLUDE_CDS
645
646 public:
647 // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
648 // These functions describe behavior for the oop not the KLASS.
649
650 // actual oop size of obj in memory in word size.
651 virtual size_t oop_size(oop obj) const = 0;
652
653 // Size of klass in word size.
654 virtual int size() const = 0;
655
656 // Returns the Java name for a class (Resource allocated)
657 // For arrays, this returns the name of the element with a leading '['.
658 // For classes, this returns the name with the package separators
659 // turned into '.'s.
660 const char* external_name() const;
661 // Returns the name for a class (Resource allocated) as the class
662 // would appear in a signature.
663 // For arrays, this returns the name of the element with a leading '['.
664 // For classes, this returns the name with a leading 'L' and a trailing ';'
665 // and the package separators as '/'.
666 virtual const char* signature_name() const;
667
668 const char* joint_in_module_of_loader(const Klass* class2, bool include_parent_loader = false) const;
669 const char* class_in_module_of_loader(bool use_are = false, bool include_parent_loader = false) const;
670
671 // Returns "interface", "abstract class" or "class".
672 const char* external_kind() const;
673
674 // type testing operations
675 #ifdef ASSERT
676 protected:
677 virtual bool is_instance_klass_slow() const { return false; }
678 virtual bool is_array_klass_slow() const { return false; }
679 virtual bool is_objArray_klass_slow() const { return false; }
680 virtual bool is_typeArray_klass_slow() const { return false; }
681 #endif // ASSERT
682 public:
683
684 // Fast non-virtual versions
685 #ifndef ASSERT
686 #define assert_same_query(xval, xcheck) xval
687 #else
688 private:
689 static bool assert_same_query(bool xval, bool xslow) {
690 assert(xval == xslow, "slow and fast queries agree");
691 return xval;
692 }
693 public:
694 #endif
695
696 bool is_instance_klass() const { return assert_same_query(_kind <= InstanceStackChunkKlassKind, is_instance_klass_slow()); }
697 // Other is anything that is not one of the more specialized kinds of InstanceKlass.
698 bool is_other_instance_klass() const { return _kind == InstanceKlassKind; }
699 bool is_reference_instance_klass() const { return _kind == InstanceRefKlassKind; }
700 bool is_mirror_instance_klass() const { return _kind == InstanceMirrorKlassKind; }
701 bool is_class_loader_instance_klass() const { return _kind == InstanceClassLoaderKlassKind; }
702 bool is_array_klass() const { return assert_same_query( _kind >= TypeArrayKlassKind, is_array_klass_slow()); }
703 bool is_stack_chunk_instance_klass() const { return _kind == InstanceStackChunkKlassKind; }
704 bool is_objArray_klass() const { return assert_same_query( _kind == ObjArrayKlassKind, is_objArray_klass_slow()); }
705 bool is_typeArray_klass() const { return assert_same_query( _kind == TypeArrayKlassKind, is_typeArray_klass_slow()); }
706 #undef assert_same_query
707
708 // Access flags
709 AccessFlags access_flags() const { return _access_flags; }
710 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
711
712 bool is_public() const { return _access_flags.is_public(); }
713 bool is_final() const { return _access_flags.is_final(); }
714 bool is_interface() const { return _access_flags.is_interface(); }
715 bool is_abstract() const { return _access_flags.is_abstract(); }
716 bool is_super() const { return _access_flags.is_super(); }
717 bool is_synthetic() const { return _access_flags.is_synthetic(); }
718 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
719 bool has_finalizer() const { return _misc_flags.has_finalizer(); }
720 void set_has_finalizer() { _misc_flags.set_has_finalizer(true); }
721 bool is_hidden() const { return _misc_flags.is_hidden_class(); }
722 void set_is_hidden() { _misc_flags.set_is_hidden_class(true); }
723 bool is_value_based() const { return _misc_flags.is_value_based_class(); }
724 void set_is_value_based() { _misc_flags.set_is_value_based_class(true); }
725
726 klass_flags_t misc_flags() const { return _misc_flags.value(); }
727
728 inline bool is_non_strong_hidden() const;
729
730 bool is_cloneable() const;
731 void set_is_cloneable();
732
733 inline markWord prototype_header() const;
734 inline void set_prototype_header(markWord header);
735 static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); }
736
737 JFR_ONLY(DEFINE_TRACE_ID_METHODS;)
738
739 virtual void metaspace_pointers_do(MetaspaceClosure* iter);
740 virtual MetaspaceObj::Type type() const { return ClassType; }
741
742 inline bool is_loader_alive() const;
743 inline bool is_loader_present_and_alive() const;
744
745 void clean_subklass();
746
747 // Clean out unnecessary weak klass links from the whole klass hierarchy.
748 static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true);
749 // Clean out unnecessary weak klass links from the given InstanceKlass.
750 static void clean_weak_instanceklass_links(InstanceKlass* ik);
751
752 // Return self, except for abstract classes with exactly 1
753 // implementor. Then return the 1 concrete implementation.
754 Klass *up_cast_abstract();
755
756 // klass name
757 Symbol* name() const { return _name; }
758 void set_name(Symbol* n);
759
760 virtual void release_C_heap_structures(bool release_constant_pool = true);
761
762 public:
763 // Get modifier flags from Java mirror cache.
764 int modifier_flags() const;
765
766 // Compute modifier flags from the original data. This also allows
767 // accessing flags when Java mirror is already dead, e.g. during class
768 // unloading.
769 virtual u2 compute_modifier_flags() const = 0;
770
771 // JVMTI support
772 virtual jint jvmti_class_status() const;
773
774 // Printing
775 virtual void print_on(outputStream* st) const;
776
777 virtual void oop_print_value_on(oop obj, outputStream* st);
778 virtual void oop_print_on (oop obj, outputStream* st);
779
780 void print_secondary_supers_on(outputStream* st) const;
781
782 virtual const char* internal_name() const = 0;
783
784 // Verification
785 virtual void verify_on(outputStream* st);
786 void verify() { verify_on(tty); }
787
788 #ifndef PRODUCT
789 bool verify_vtable_index(int index);
790 #endif
791
792 virtual void oop_verify_on(oop obj, outputStream* st);
793
794 // for error reporting
795 static bool is_valid(Klass* k);
796
797 static void on_secondary_supers_verification_failure(Klass* super, Klass* sub, bool linear_result, bool table_result, const char* msg);
798
799 // Returns true if this Klass needs to be addressable via narrow Klass ID.
800 inline bool needs_narrow_id() const;
801
802 };
803
804 #endif // SHARE_OOPS_KLASS_HPP