1 /*
2 * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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23 */
24
25 #ifndef SHARE_OOPS_KLASS_HPP
26 #define SHARE_OOPS_KLASS_HPP
27
28 #include "memory/iterator.hpp"
29 #include "memory/memRegion.hpp"
30 #include "oops/klassFlags.hpp"
31 #include "oops/markWord.hpp"
32 #include "oops/metadata.hpp"
33 #include "oops/oop.hpp"
34 #include "oops/oopHandle.hpp"
35 #include "utilities/accessFlags.hpp"
36 #include "utilities/macros.hpp"
37 #if INCLUDE_JFR
38 #include "jfr/support/jfrTraceIdExtension.hpp"
39 #endif
40
41 //
42 // A Klass provides:
43 // 1: language level class object (method dictionary etc.)
44 // 2: provide vm dispatch behavior for the object
45 // Both functions are combined into one C++ class.
46
47 // One reason for the oop/klass dichotomy in the implementation is
48 // that we don't want a C++ vtbl pointer in every object. Thus,
49 // normal oops don't have any virtual functions. Instead, they
50 // forward all "virtual" functions to their klass, which does have
51 // a vtbl and does the C++ dispatch depending on the object's
52 // actual type. (See oop.inline.hpp for some of the forwarding code.)
53 // ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"!
54
55 // Forward declarations.
56 template <class T> class Array;
57 template <class T> class GrowableArray;
58 class ClassLoaderData;
59 class fieldDescriptor;
60 class klassVtable;
61 class ModuleEntry;
62 class PackageEntry;
63 class ParCompactionManager;
64 class PSPromotionManager;
65 class vtableEntry;
66
67 class Klass : public Metadata {
68
69 friend class VMStructs;
70 friend class JVMCIVMStructs;
71 public:
72 // Klass Kinds for all subclasses of Klass
73 enum KlassKind {
74 InstanceKlassKind,
75 InstanceRefKlassKind,
76 InstanceMirrorKlassKind,
77 InstanceClassLoaderKlassKind,
78 InstanceStackChunkKlassKind,
79 TypeArrayKlassKind,
80 ObjArrayKlassKind,
81 UnknownKlassKind
82 };
83
84 static const uint KLASS_KIND_COUNT = ObjArrayKlassKind + 1;
85 protected:
86
87 // If you add a new field that points to any metaspace object, you
88 // must add this field to Klass::metaspace_pointers_do().
89
90 // note: put frequently-used fields together at start of klass structure
91 // for better cache behavior (may not make much of a difference but sure won't hurt)
92 enum { _primary_super_limit = 8 };
93
94 // The "layout helper" is a combined descriptor of object layout.
95 // For klasses which are neither instance nor array, the value is zero.
96 //
97 // For instances, layout helper is a positive number, the instance size.
98 // This size is already passed through align_object_size and scaled to bytes.
99 // The low order bit is set if instances of this class cannot be
100 // allocated using the fastpath.
101 //
102 // For arrays, layout helper is a negative number, containing four
103 // distinct bytes, as follows:
104 // MSB:[tag, hsz, ebt, log2(esz)]:LSB
105 // where:
106 // tag is 0x80 if the elements are oops, 0xC0 if non-oops
107 // hsz is array header size in bytes (i.e., offset of first element)
108 // ebt is the BasicType of the elements
109 // esz is the element size in bytes
110 // This packed word is arranged so as to be quickly unpacked by the
111 // various fast paths that use the various subfields.
112 //
113 // The esz bits can be used directly by a SLL instruction, without masking.
114 //
115 // Note that the array-kind tag looks like 0x00 for instance klasses,
116 // since their length in bytes is always less than 24Mb.
117 //
118 // Final note: This comes first, immediately after C++ vtable,
119 // because it is frequently queried.
120 jint _layout_helper;
121
122 // Klass kind used to resolve the runtime type of the instance.
123 // - Used to implement devirtualized oop closure dispatching.
124 // - Various type checking in the JVM
125 const KlassKind _kind;
126
127 // Processed access flags, for use by Class.getModifiers.
128 jint _modifier_flags;
129
130 // The fields _super_check_offset, _secondary_super_cache, _secondary_supers
131 // and _primary_supers all help make fast subtype checks. See big discussion
132 // in doc/server_compiler/checktype.txt
133 //
134 // Where to look to observe a supertype (it is &_secondary_super_cache for
135 // secondary supers, else is &_primary_supers[depth()].
136 juint _super_check_offset;
137
138 // Class name. Instance classes: java/lang/String, etc. Array classes: [I,
139 // [Ljava/lang/String;, etc. Set to zero for all other kinds of classes.
140 Symbol* _name;
141
142 // Cache of last observed secondary supertype
143 Klass* _secondary_super_cache;
144 // Array of all secondary supertypes
145 Array<Klass*>* _secondary_supers;
146 // Ordered list of all primary supertypes
147 Klass* _primary_supers[_primary_super_limit];
148 // java/lang/Class instance mirroring this class
149 OopHandle _java_mirror;
150 // Superclass
151 Klass* _super;
152 // First subclass (null if none); _subklass->next_sibling() is next one
153 Klass* volatile _subklass;
154 // Sibling link (or null); links all subklasses of a klass
155 Klass* volatile _next_sibling;
156
157 // All klasses loaded by a class loader are chained through these links
158 Klass* _next_link;
159
160 // The VM's representation of the ClassLoader used to load this class.
161 // Provide access the corresponding instance java.lang.ClassLoader.
162 ClassLoaderData* _class_loader_data;
163
164 // Bitmap and hash code used by hashed secondary supers.
165 uintx _secondary_supers_bitmap;
166 uint8_t _hash_slot;
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 // Some flags created by the JVM, not in the class file itself,
174 // are in _misc_flags below.
175
176 JFR_ONLY(DEFINE_TRACE_ID_FIELD;)
177
178 private:
179 // This is an index into FileMapHeader::_shared_path_table[], to
180 // associate this class with the JAR file where it's loaded from during
181 // dump time. If a class is not loaded from the shared archive, this field is
182 // -1.
183 s2 _shared_class_path_index;
184
185 #if INCLUDE_CDS
186 // Various attributes for shared classes. Should be zero for a non-shared class.
187 u2 _shared_class_flags;
188 enum CDSSharedClassFlags {
189 _is_shared_class = 1 << 0, // shadows MetaspaceObj::is_shared
190 _archived_lambda_proxy_is_available = 1 << 1,
191 _has_value_based_class_annotation = 1 << 2,
192 _verified_at_dump_time = 1 << 3,
193 _has_archived_enum_objs = 1 << 4,
194 // This class was not loaded from a classfile in the module image
195 // or classpath.
196 _is_generated_shared_class = 1 << 5
197 };
198 #endif
199
200 KlassFlags _misc_flags;
201
202 CDS_JAVA_HEAP_ONLY(int _archived_mirror_index;)
203
204 protected:
205
206 Klass(KlassKind kind);
207 Klass();
208
209 public:
210 int kind() { return _kind; }
211
212 enum class DefaultsLookupMode { find, skip };
213 enum class OverpassLookupMode { find, skip };
214 enum class StaticLookupMode { find, skip };
215 enum class PrivateLookupMode { find, skip };
216
217 virtual bool is_klass() const { return true; }
218
219 // super() cannot be InstanceKlass* -- Java arrays are covariant, and _super is used
220 // to implement that. NB: the _super of "[Ljava/lang/Integer;" is "[Ljava/lang/Number;"
221 // If this is not what your code expects, you're probably looking for Klass::java_super().
222 Klass* super() const { return _super; }
223 void set_super(Klass* k) { _super = k; }
224
225 // initializes _super link, _primary_supers & _secondary_supers arrays
226 void initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS);
227
228 // klass-specific helper for initializing _secondary_supers
229 virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots,
230 Array<InstanceKlass*>* transitive_interfaces);
231
232 // java_super is the Java-level super type as specified by Class.getSuperClass.
233 virtual InstanceKlass* java_super() const { return nullptr; }
234
235 juint super_check_offset() const { return _super_check_offset; }
236 void set_super_check_offset(juint o) { _super_check_offset = o; }
237
238 Klass* secondary_super_cache() const { return _secondary_super_cache; }
239 void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; }
240
241 Array<Klass*>* secondary_supers() const { return _secondary_supers; }
242 void set_secondary_supers(Array<Klass*>* k, uintx bitmap);
243
244 uint8_t hash_slot() const { return _hash_slot; }
245
246 // Return the element of the _super chain of the given depth.
247 // If there is no such element, return either null or this.
248 Klass* primary_super_of_depth(juint i) const {
249 assert(i < primary_super_limit(), "oob");
250 Klass* super = _primary_supers[i];
251 assert(super == nullptr || super->super_depth() == i, "correct display");
252 return super;
253 }
254
255 // Can this klass be a primary super? False for interfaces and arrays of
256 // interfaces. False also for arrays or classes with long super chains.
257 bool can_be_primary_super() const {
258 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
259 return super_check_offset() != secondary_offset;
260 }
261 virtual bool can_be_primary_super_slow() const;
262
263 // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit].
264 juint super_depth() const {
265 if (!can_be_primary_super()) {
266 return primary_super_limit();
267 } else {
268 juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*);
269 assert(d < primary_super_limit(), "oob");
270 assert(_primary_supers[d] == this, "proper init");
271 return d;
272 }
273 }
274
275 // java mirror
276 oop java_mirror() const;
277 oop java_mirror_no_keepalive() const;
278 void set_java_mirror(Handle m);
279
280 oop archived_java_mirror() NOT_CDS_JAVA_HEAP_RETURN_(nullptr);
281 void set_archived_java_mirror(int mirror_index) NOT_CDS_JAVA_HEAP_RETURN;
282
283 // Temporary mirror switch used by RedefineClasses
284 OopHandle java_mirror_handle() const { return _java_mirror; }
285 void swap_java_mirror_handle(OopHandle& mirror) { _java_mirror.swap(mirror); }
286
287 // Set java mirror OopHandle to null for CDS
288 // This leaves the OopHandle in the CLD, but that's ok, you can't release them.
289 void clear_java_mirror_handle() { _java_mirror = OopHandle(); }
290
291 // modifier flags
292 jint modifier_flags() const { return _modifier_flags; }
293 void set_modifier_flags(jint flags) { _modifier_flags = flags; }
294
295 // size helper
296 int layout_helper() const { return _layout_helper; }
297 void set_layout_helper(int lh) { _layout_helper = lh; }
298
299 // Note: for instances layout_helper() may include padding.
300 // Use InstanceKlass::contains_field_offset to classify field offsets.
301
302 // sub/superklass links
303 Klass* subklass(bool log = false) const;
304 Klass* next_sibling(bool log = false) const;
305
306 InstanceKlass* superklass() const;
307 void append_to_sibling_list(); // add newly created receiver to superklass' subklass list
308
309 void set_next_link(Klass* k) { _next_link = k; }
310 Klass* next_link() const { return _next_link; } // The next klass defined by the class loader.
311 Klass** next_link_addr() { return &_next_link; }
312
313 // class loader data
314 ClassLoaderData* class_loader_data() const { return _class_loader_data; }
315 void set_class_loader_data(ClassLoaderData* loader_data) { _class_loader_data = loader_data; }
316
317 s2 shared_classpath_index() const {
318 return _shared_class_path_index;
319 };
320
321 void set_shared_classpath_index(s2 index) {
322 _shared_class_path_index = index;
323 };
324
325 bool has_archived_mirror_index() const {
326 CDS_JAVA_HEAP_ONLY(return _archived_mirror_index >= 0;)
327 NOT_CDS_JAVA_HEAP(return false);
328 }
329
330 void clear_archived_mirror_index() NOT_CDS_JAVA_HEAP_RETURN;
331
332 void set_lambda_proxy_is_available() {
333 CDS_ONLY(_shared_class_flags |= _archived_lambda_proxy_is_available;)
334 }
335 void clear_lambda_proxy_is_available() {
336 CDS_ONLY(_shared_class_flags &= (u2)(~_archived_lambda_proxy_is_available);)
337 }
338 bool lambda_proxy_is_available() const {
339 CDS_ONLY(return (_shared_class_flags & _archived_lambda_proxy_is_available) != 0;)
340 NOT_CDS(return false;)
341 }
342
343 void set_has_value_based_class_annotation() {
344 CDS_ONLY(_shared_class_flags |= _has_value_based_class_annotation;)
345 }
346 void clear_has_value_based_class_annotation() {
347 CDS_ONLY(_shared_class_flags &= (u2)(~_has_value_based_class_annotation);)
348 }
349 bool has_value_based_class_annotation() const {
350 CDS_ONLY(return (_shared_class_flags & _has_value_based_class_annotation) != 0;)
351 NOT_CDS(return false;)
352 }
353
354 void set_verified_at_dump_time() {
355 CDS_ONLY(_shared_class_flags |= _verified_at_dump_time;)
356 }
357 bool verified_at_dump_time() const {
358 CDS_ONLY(return (_shared_class_flags & _verified_at_dump_time) != 0;)
359 NOT_CDS(return false;)
360 }
361
362 void set_has_archived_enum_objs() {
363 CDS_ONLY(_shared_class_flags |= _has_archived_enum_objs;)
364 }
365 bool has_archived_enum_objs() const {
366 CDS_ONLY(return (_shared_class_flags & _has_archived_enum_objs) != 0;)
367 NOT_CDS(return false;)
368 }
369
370 void set_is_generated_shared_class() {
371 CDS_ONLY(_shared_class_flags |= _is_generated_shared_class;)
372 }
373 bool is_generated_shared_class() const {
374 CDS_ONLY(return (_shared_class_flags & _is_generated_shared_class) != 0;)
375 NOT_CDS(return false;)
376 }
377
378 bool is_shared() const { // shadows MetaspaceObj::is_shared)()
379 CDS_ONLY(return (_shared_class_flags & _is_shared_class) != 0;)
380 NOT_CDS(return false;)
381 }
382
383 void set_is_shared() {
384 CDS_ONLY(_shared_class_flags |= _is_shared_class;)
385 }
386
387 // Obtain the module or package for this class
388 virtual ModuleEntry* module() const = 0;
389 virtual PackageEntry* package() const = 0;
390
391 protected: // internal accessors
392 void set_subklass(Klass* s);
393 void set_next_sibling(Klass* s);
394
395 private:
396 static uint8_t compute_hash_slot(Symbol* s);
397 static void hash_insert(Klass* klass, GrowableArray<Klass*>* secondaries, uintx& bitmap);
398 static uintx hash_secondary_supers(Array<Klass*>* secondaries, bool rewrite);
399
400 bool search_secondary_supers(Klass* k) const;
401 bool lookup_secondary_supers_table(Klass *k) const;
402 bool linear_search_secondary_supers(const Klass* k) const;
403 bool fallback_search_secondary_supers(const Klass* k, int index, uintx rotated_bitmap) const;
404
405 public:
406 // Secondary supers table support
407 static Array<Klass*>* pack_secondary_supers(ClassLoaderData* loader_data,
408 GrowableArray<Klass*>* primaries,
409 GrowableArray<Klass*>* secondaries,
410 uintx& bitmap,
411 TRAPS);
412
413 static uintx compute_secondary_supers_bitmap(Array<Klass*>* secondary_supers);
414 static uint8_t compute_home_slot(Klass* k, uintx bitmap);
415
416 static constexpr int SECONDARY_SUPERS_TABLE_SIZE = sizeof(_secondary_supers_bitmap) * 8;
417 static constexpr int SECONDARY_SUPERS_TABLE_MASK = SECONDARY_SUPERS_TABLE_SIZE - 1;
418
419 static constexpr uintx SECONDARY_SUPERS_BITMAP_EMPTY = 0;
420 static constexpr uintx SECONDARY_SUPERS_BITMAP_FULL = ~(uintx)0;
421
422 // Compiler support
423 static ByteSize super_offset() { return byte_offset_of(Klass, _super); }
424 static ByteSize super_check_offset_offset() { return byte_offset_of(Klass, _super_check_offset); }
425 static ByteSize primary_supers_offset() { return byte_offset_of(Klass, _primary_supers); }
426 static ByteSize secondary_super_cache_offset() { return byte_offset_of(Klass, _secondary_super_cache); }
427 static ByteSize secondary_supers_offset() { return byte_offset_of(Klass, _secondary_supers); }
428 static ByteSize java_mirror_offset() { return byte_offset_of(Klass, _java_mirror); }
429 static ByteSize class_loader_data_offset() { return byte_offset_of(Klass, _class_loader_data); }
430 static ByteSize modifier_flags_offset() { return byte_offset_of(Klass, _modifier_flags); }
431 static ByteSize layout_helper_offset() { return byte_offset_of(Klass, _layout_helper); }
432 static ByteSize access_flags_offset() { return byte_offset_of(Klass, _access_flags); }
433 #if INCLUDE_JVMCI
434 static ByteSize subklass_offset() { return byte_offset_of(Klass, _subklass); }
435 static ByteSize next_sibling_offset() { return byte_offset_of(Klass, _next_sibling); }
436 #endif
437 static ByteSize secondary_supers_bitmap_offset()
438 { return byte_offset_of(Klass, _secondary_supers_bitmap); }
439 static ByteSize hash_slot_offset() { return byte_offset_of(Klass, _hash_slot); }
440 static ByteSize misc_flags_offset() { return byte_offset_of(Klass, _misc_flags._flags); }
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
541 // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
542 bool is_subtype_of(Klass* k) const;
543
544 public:
545 // Find LCA in class hierarchy
546 Klass *LCA( Klass *k );
547
548 // Check whether reflection/jni/jvm code is allowed to instantiate this class;
549 // if not, throw either an Error or an Exception.
550 virtual void check_valid_for_instantiation(bool throwError, TRAPS);
551
552 // array copying
553 virtual void copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
554
555 // tells if the class should be initialized
556 virtual bool should_be_initialized() const { return false; }
557 // initializes the klass
558 virtual void initialize(TRAPS);
559 virtual Klass* find_field(Symbol* name, Symbol* signature, fieldDescriptor* fd) const;
560 virtual Method* uncached_lookup_method(const Symbol* name, const Symbol* signature,
561 OverpassLookupMode overpass_mode,
562 PrivateLookupMode = PrivateLookupMode::find) const;
563 public:
564 Method* lookup_method(const Symbol* name, const Symbol* signature) const {
565 return uncached_lookup_method(name, signature, OverpassLookupMode::find);
566 }
567
568 // array class with specific rank
569 virtual ArrayKlass* array_klass(int rank, TRAPS) = 0;
570
571 // array class with this klass as element type
572 virtual ArrayKlass* array_klass(TRAPS) = 0;
573
574 // These will return null instead of allocating on the heap:
575 virtual ArrayKlass* array_klass_or_null(int rank) = 0;
576 virtual ArrayKlass* array_klass_or_null() = 0;
577
578 virtual oop protection_domain() const = 0;
579
580 oop class_loader() const;
581
582 inline oop klass_holder() const;
583
584 protected:
585
586 // Error handling when length > max_length or length < 0
587 static void check_array_allocation_length(int length, int max_length, TRAPS);
588
589 void set_vtable_length(int len) { _vtable_len= len; }
590
591 vtableEntry* start_of_vtable() const;
592 #if INCLUDE_CDS
593 void restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS);
594 #endif
595 public:
596 Method* method_at_vtable(int index);
597
598 static ByteSize vtable_start_offset();
599 static ByteSize vtable_length_offset() {
600 return byte_offset_of(Klass, _vtable_len);
601 }
602
603 #if INCLUDE_CDS
604 // CDS support - remove and restore oops from metadata. Oops are not shared.
605 virtual void remove_unshareable_info();
606 virtual void remove_java_mirror();
607
608 bool is_unshareable_info_restored() const {
609 assert(is_shared(), "use this for shared classes only");
610 if (has_archived_mirror_index()) {
611 // _java_mirror is not a valid OopHandle but rather an encoded reference in the shared heap
612 return false;
613 } else if (_java_mirror.is_empty()) {
614 return false;
615 } else {
616 return true;
617 }
618 }
619 #endif // INCLUDE_CDS
620
621 public:
622 // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
623 // These functions describe behavior for the oop not the KLASS.
624
625 // actual oop size of obj in memory in word size.
626 virtual size_t oop_size(oop obj) const = 0;
627
628 // Size of klass in word size.
629 virtual int size() const = 0;
630
631 // Returns the Java name for a class (Resource allocated)
632 // For arrays, this returns the name of the element with a leading '['.
633 // For classes, this returns the name with the package separators
634 // turned into '.'s.
635 const char* external_name() const;
636 // Returns the name for a class (Resource allocated) as the class
637 // would appear in a signature.
638 // For arrays, this returns the name of the element with a leading '['.
639 // For classes, this returns the name with a leading 'L' and a trailing ';'
640 // and the package separators as '/'.
641 virtual const char* signature_name() const;
642
643 const char* joint_in_module_of_loader(const Klass* class2, bool include_parent_loader = false) const;
644 const char* class_in_module_of_loader(bool use_are = false, bool include_parent_loader = false) const;
645
646 // Returns "interface", "abstract class" or "class".
647 const char* external_kind() const;
648
649 // type testing operations
650 #ifdef ASSERT
651 protected:
652 virtual bool is_instance_klass_slow() const { return false; }
653 virtual bool is_array_klass_slow() const { return false; }
654 virtual bool is_objArray_klass_slow() const { return false; }
655 virtual bool is_typeArray_klass_slow() const { return false; }
656 #endif // ASSERT
657 public:
658
659 // Fast non-virtual versions
660 #ifndef ASSERT
661 #define assert_same_query(xval, xcheck) xval
662 #else
663 private:
664 static bool assert_same_query(bool xval, bool xslow) {
665 assert(xval == xslow, "slow and fast queries agree");
666 return xval;
667 }
668 public:
669 #endif
670
671 bool is_instance_klass() const { return assert_same_query(_kind <= InstanceStackChunkKlassKind, is_instance_klass_slow()); }
672 // Other is anything that is not one of the more specialized kinds of InstanceKlass.
673 bool is_other_instance_klass() const { return _kind == InstanceKlassKind; }
674 bool is_reference_instance_klass() const { return _kind == InstanceRefKlassKind; }
675 bool is_mirror_instance_klass() const { return _kind == InstanceMirrorKlassKind; }
676 bool is_class_loader_instance_klass() const { return _kind == InstanceClassLoaderKlassKind; }
677 bool is_array_klass() const { return assert_same_query( _kind >= TypeArrayKlassKind, is_array_klass_slow()); }
678 bool is_stack_chunk_instance_klass() const { return _kind == InstanceStackChunkKlassKind; }
679 bool is_objArray_klass() const { return assert_same_query( _kind == ObjArrayKlassKind, is_objArray_klass_slow()); }
680 bool is_typeArray_klass() const { return assert_same_query( _kind == TypeArrayKlassKind, is_typeArray_klass_slow()); }
681 #undef assert_same_query
682
683 // Access flags
684 AccessFlags access_flags() const { return _access_flags; }
685 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
686
687 bool is_public() const { return _access_flags.is_public(); }
688 bool is_final() const { return _access_flags.is_final(); }
689 bool is_interface() const { return _access_flags.is_interface(); }
690 bool is_abstract() const { return _access_flags.is_abstract(); }
691 bool is_super() const { return _access_flags.is_super(); }
692 bool is_synthetic() const { return _access_flags.is_synthetic(); }
693 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
694 bool has_finalizer() const { return _misc_flags.has_finalizer(); }
695 void set_has_finalizer() { _misc_flags.set_has_finalizer(true); }
696 bool is_hidden() const { return _misc_flags.is_hidden_class(); }
697 void set_is_hidden() { _misc_flags.set_is_hidden_class(true); }
698 bool is_value_based() const { return _misc_flags.is_value_based_class(); }
699 void set_is_value_based() { _misc_flags.set_is_value_based_class(true); }
700
701 klass_flags_t misc_flags() const { return _misc_flags.value(); }
702
703 inline bool is_non_strong_hidden() const;
704
705 bool is_cloneable() const;
706 void set_is_cloneable();
707
708 JFR_ONLY(DEFINE_TRACE_ID_METHODS;)
709
710 virtual void metaspace_pointers_do(MetaspaceClosure* iter);
711 virtual MetaspaceObj::Type type() const { return ClassType; }
712
713 inline bool is_loader_alive() const;
714
715 void clean_subklass();
716
717 static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true);
718 static void clean_subklass_tree() {
719 clean_weak_klass_links(/*unloading_occurred*/ true , /* clean_alive_klasses */ false);
720 }
721
722 // Return self, except for abstract classes with exactly 1
723 // implementor. Then return the 1 concrete implementation.
724 Klass *up_cast_abstract();
725
726 // klass name
727 Symbol* name() const { return _name; }
728 void set_name(Symbol* n);
729
730 virtual void release_C_heap_structures(bool release_constant_pool = true);
731
732 public:
733 virtual jint compute_modifier_flags() const = 0;
734
735 // JVMTI support
736 virtual jint jvmti_class_status() const;
737
738 // Printing
739 virtual void print_on(outputStream* st) const;
740
741 virtual void oop_print_value_on(oop obj, outputStream* st);
742 virtual void oop_print_on (oop obj, outputStream* st);
743
744 void print_secondary_supers_on(outputStream* st) const;
745
746 virtual const char* internal_name() const = 0;
747
748 // Verification
749 virtual void verify_on(outputStream* st);
750 void verify() { verify_on(tty); }
751
752 #ifndef PRODUCT
753 bool verify_vtable_index(int index);
754 #endif
755
756 virtual void oop_verify_on(oop obj, outputStream* st);
757
758 // for error reporting
759 static bool is_valid(Klass* k);
760
761 static void on_secondary_supers_verification_failure(Klass* super, Klass* sub, bool linear_result, bool table_result, const char* msg);
762 };
763
764 #endif // SHARE_OOPS_KLASS_HPP