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/markWord.hpp"
31 #include "oops/metadata.hpp"
32 #include "oops/oop.hpp"
33 #include "oops/oopHandle.hpp"
34 #include "utilities/accessFlags.hpp"
35 #include "utilities/macros.hpp"
36 #if INCLUDE_JFR
37 #include "jfr/support/jfrTraceIdExtension.hpp"
38 #endif
39
40 //
41 // A Klass provides:
42 // 1: language level class object (method dictionary etc.)
43 // 2: provide vm dispatch behavior for the object
44 // Both functions are combined into one C++ class.
45
46 // One reason for the oop/klass dichotomy in the implementation is
47 // that we don't want a C++ vtbl pointer in every object. Thus,
48 // normal oops don't have any virtual functions. Instead, they
49 // forward all "virtual" functions to their klass, which does have
50 // a vtbl and does the C++ dispatch depending on the object's
51 // actual type. (See oop.inline.hpp for some of the forwarding code.)
52 // ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"!
53
54 // Forward declarations.
55 template <class T> class Array;
56 template <class T> class GrowableArray;
57 class ClassLoaderData;
58 class fieldDescriptor;
59 class klassVtable;
60 class ModuleEntry;
61 class PackageEntry;
62 class ParCompactionManager;
63 class PSPromotionManager;
64 class vtableEntry;
65
66 class Klass : public Metadata {
67 friend class VMStructs;
68 friend class JVMCIVMStructs;
69 public:
70 // Klass Kinds for all subclasses of Klass
71 enum KlassKind {
72 InstanceKlassKind,
73 InlineKlassKind,
74 InstanceRefKlassKind,
75 InstanceMirrorKlassKind,
76 InstanceClassLoaderKlassKind,
77 InstanceStackChunkKlassKind,
78 TypeArrayKlassKind,
79 FlatArrayKlassKind,
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, 0xA0 if value types
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 int _vtable_len; // vtable length. This field may be read very often when we
165 // have lots of itable dispatches (e.g., lambdas and streams).
166 // Keep it away from the beginning of a Klass to avoid cacheline
167 // contention that may happen when a nearby object is modified.
168 AccessFlags _access_flags; // Access flags. The class/interface distinction is stored here.
169
170 JFR_ONLY(DEFINE_TRACE_ID_FIELD;)
171
172 markWord _prototype_header; // inline type and inline array mark patterns
173 private:
174 // This is an index into FileMapHeader::_shared_path_table[], to
175 // associate this class with the JAR file where it's loaded from during
176 // dump time. If a class is not loaded from the shared archive, this field is
177 // -1.
178 s2 _shared_class_path_index;
179
180 #if INCLUDE_CDS
181 // Various attributes for shared classes. Should be zero for a non-shared class.
182 u2 _shared_class_flags;
183 enum CDSSharedClassFlags {
184 _is_shared_class = 1 << 0, // shadows MetaspaceObj::is_shared
185 _archived_lambda_proxy_is_available = 1 << 1,
186 _has_value_based_class_annotation = 1 << 2,
187 _verified_at_dump_time = 1 << 3,
188 _has_archived_enum_objs = 1 << 4,
189 // This class was not loaded from a classfile in the module image
190 // or classpath.
191 _is_generated_shared_class = 1 << 5
192 };
193 #endif
194
195 CDS_JAVA_HEAP_ONLY(int _archived_mirror_index;)
196
197 protected:
198
199 Klass(KlassKind kind);
200 Klass();
201
202 void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw();
203
204 public:
205 int kind() { return _kind; }
206
207 enum class DefaultsLookupMode { find, skip };
208 enum class OverpassLookupMode { find, skip };
209 enum class StaticLookupMode { find, skip };
210 enum class PrivateLookupMode { find, skip };
211
212 virtual bool is_klass() const { return true; }
213
214 // super() cannot be InstanceKlass* -- Java arrays are covariant, and _super is used
215 // to implement that. NB: the _super of "[Ljava/lang/Integer;" is "[Ljava/lang/Number;"
216 // If this is not what your code expects, you're probably looking for Klass::java_super().
217 Klass* super() const { return _super; }
218 void set_super(Klass* k) { _super = k; }
219
220 // initializes _super link, _primary_supers & _secondary_supers arrays
221 void initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS);
222
223 // klass-specific helper for initializing _secondary_supers
224 virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots,
225 Array<InstanceKlass*>* transitive_interfaces);
226
227 // java_super is the Java-level super type as specified by Class.getSuperClass.
228 virtual InstanceKlass* java_super() const { return nullptr; }
229
230 juint super_check_offset() const { return _super_check_offset; }
231 void set_super_check_offset(juint o) { _super_check_offset = o; }
232
233 Klass* secondary_super_cache() const { return _secondary_super_cache; }
234 void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; }
235
236 Array<Klass*>* secondary_supers() const { return _secondary_supers; }
237 void set_secondary_supers(Array<Klass*>* k) { _secondary_supers = k; }
238
239 // Return the element of the _super chain of the given depth.
240 // If there is no such element, return either null or this.
241 Klass* primary_super_of_depth(juint i) const {
242 assert(i < primary_super_limit(), "oob");
243 Klass* super = _primary_supers[i];
244 assert(super == nullptr || super->super_depth() == i, "correct display");
245 return super;
246 }
247
248 // Can this klass be a primary super? False for interfaces and arrays of
249 // interfaces. False also for arrays or classes with long super chains.
250 bool can_be_primary_super() const {
251 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
252 return super_check_offset() != secondary_offset;
253 }
254 virtual bool can_be_primary_super_slow() const;
255
256 // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit].
257 juint super_depth() const {
258 if (!can_be_primary_super()) {
259 return primary_super_limit();
260 } else {
261 juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*);
262 assert(d < primary_super_limit(), "oob");
263 assert(_primary_supers[d] == this, "proper init");
264 return d;
265 }
266 }
267
268 // java mirror
269 oop java_mirror() const;
270 oop java_mirror_no_keepalive() const;
271 void set_java_mirror(Handle m);
272
273 oop archived_java_mirror() NOT_CDS_JAVA_HEAP_RETURN_(nullptr);
274 void set_archived_java_mirror(int mirror_index) NOT_CDS_JAVA_HEAP_RETURN;
275
276 // Temporary mirror switch used by RedefineClasses
277 OopHandle java_mirror_handle() const { return _java_mirror; }
278 void swap_java_mirror_handle(OopHandle& mirror) { _java_mirror.swap(mirror); }
279
280 // Set java mirror OopHandle to null for CDS
281 // This leaves the OopHandle in the CLD, but that's ok, you can't release them.
282 void clear_java_mirror_handle() { _java_mirror = OopHandle(); }
283
284 // modifier flags
285 jint modifier_flags() const { return _modifier_flags; }
286 void set_modifier_flags(jint flags) { _modifier_flags = flags; }
287
288 // size helper
289 int layout_helper() const { return _layout_helper; }
290 void set_layout_helper(int lh) { _layout_helper = lh; }
291
292 // Note: for instances layout_helper() may include padding.
293 // Use InstanceKlass::contains_field_offset to classify field offsets.
294
295 // sub/superklass links
296 Klass* subklass(bool log = false) const;
297 Klass* next_sibling(bool log = false) const;
298
299 InstanceKlass* superklass() const;
300 void append_to_sibling_list(); // add newly created receiver to superklass' subklass list
301
302 void set_next_link(Klass* k) { _next_link = k; }
303 Klass* next_link() const { return _next_link; } // The next klass defined by the class loader.
304 Klass** next_link_addr() { return &_next_link; }
305
306 // class loader data
307 ClassLoaderData* class_loader_data() const { return _class_loader_data; }
308 void set_class_loader_data(ClassLoaderData* loader_data) { _class_loader_data = loader_data; }
309
310 s2 shared_classpath_index() const {
311 return _shared_class_path_index;
312 };
313
314 void set_shared_classpath_index(s2 index) {
315 _shared_class_path_index = index;
316 };
317
318 bool has_archived_mirror_index() const {
319 CDS_JAVA_HEAP_ONLY(return _archived_mirror_index >= 0;)
320 NOT_CDS_JAVA_HEAP(return false);
321 }
322
323 void clear_archived_mirror_index() NOT_CDS_JAVA_HEAP_RETURN;
324
325 void set_lambda_proxy_is_available() {
326 CDS_ONLY(_shared_class_flags |= _archived_lambda_proxy_is_available;)
327 }
328 void clear_lambda_proxy_is_available() {
329 CDS_ONLY(_shared_class_flags &= (u2)(~_archived_lambda_proxy_is_available);)
330 }
331 bool lambda_proxy_is_available() const {
332 CDS_ONLY(return (_shared_class_flags & _archived_lambda_proxy_is_available) != 0;)
333 NOT_CDS(return false;)
334 }
335
336 void set_has_value_based_class_annotation() {
337 CDS_ONLY(_shared_class_flags |= _has_value_based_class_annotation;)
338 }
339 void clear_has_value_based_class_annotation() {
340 CDS_ONLY(_shared_class_flags &= (u2)(~_has_value_based_class_annotation);)
341 }
342 bool has_value_based_class_annotation() const {
343 CDS_ONLY(return (_shared_class_flags & _has_value_based_class_annotation) != 0;)
344 NOT_CDS(return false;)
345 }
346
347 void set_verified_at_dump_time() {
348 CDS_ONLY(_shared_class_flags |= _verified_at_dump_time;)
349 }
350 bool verified_at_dump_time() const {
351 CDS_ONLY(return (_shared_class_flags & _verified_at_dump_time) != 0;)
352 NOT_CDS(return false;)
353 }
354
355 void set_has_archived_enum_objs() {
356 CDS_ONLY(_shared_class_flags |= _has_archived_enum_objs;)
357 }
358 bool has_archived_enum_objs() const {
359 CDS_ONLY(return (_shared_class_flags & _has_archived_enum_objs) != 0;)
360 NOT_CDS(return false;)
361 }
362
363 void set_is_generated_shared_class() {
364 CDS_ONLY(_shared_class_flags |= _is_generated_shared_class;)
365 }
366 bool is_generated_shared_class() const {
367 CDS_ONLY(return (_shared_class_flags & _is_generated_shared_class) != 0;)
368 NOT_CDS(return false;)
369 }
370
371 bool is_shared() const { // shadows MetaspaceObj::is_shared)()
372 CDS_ONLY(return (_shared_class_flags & _is_shared_class) != 0;)
373 NOT_CDS(return false;)
374 }
375
376 void set_is_shared() {
377 CDS_ONLY(_shared_class_flags |= _is_shared_class;)
378 }
379
380 // Obtain the module or package for this class
381 virtual ModuleEntry* module() const = 0;
382 virtual PackageEntry* package() const = 0;
383
384 protected: // internal accessors
385 void set_subklass(Klass* s);
386 void set_next_sibling(Klass* s);
387
388 public:
389
390 // Compiler support
391 static ByteSize super_offset() { return byte_offset_of(Klass, _super); }
392 static ByteSize super_check_offset_offset() { return byte_offset_of(Klass, _super_check_offset); }
393 static ByteSize primary_supers_offset() { return byte_offset_of(Klass, _primary_supers); }
394 static ByteSize secondary_super_cache_offset() { return byte_offset_of(Klass, _secondary_super_cache); }
395 static ByteSize secondary_supers_offset() { return byte_offset_of(Klass, _secondary_supers); }
396 static ByteSize java_mirror_offset() { return byte_offset_of(Klass, _java_mirror); }
397 static ByteSize class_loader_data_offset() { return byte_offset_of(Klass, _class_loader_data); }
398 static ByteSize modifier_flags_offset() { return byte_offset_of(Klass, _modifier_flags); }
399 static ByteSize layout_helper_offset() { return byte_offset_of(Klass, _layout_helper); }
400 static ByteSize access_flags_offset() { return byte_offset_of(Klass, _access_flags); }
401 #if INCLUDE_JVMCI
402 static ByteSize subklass_offset() { return byte_offset_of(Klass, _subklass); }
403 static ByteSize next_sibling_offset() { return byte_offset_of(Klass, _next_sibling); }
404 #endif
405
406 // Unpacking layout_helper:
407 static const int _lh_neutral_value = 0; // neutral non-array non-instance value
408 static const int _lh_instance_slow_path_bit = 0x01;
409 static const int _lh_log2_element_size_shift = BitsPerByte*0;
410 static const int _lh_log2_element_size_mask = BitsPerLong-1;
411 static const int _lh_element_type_shift = BitsPerByte*1;
412 static const int _lh_element_type_mask = right_n_bits(BitsPerByte); // shifted mask
413 static const int _lh_header_size_shift = BitsPerByte*2;
414 static const int _lh_header_size_mask = right_n_bits(BitsPerByte); // shifted mask
415 static const int _lh_array_tag_bits = 3;
416 static const int _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits;
417
418 static const unsigned int _lh_array_tag_type_value = 0Xfffffffc;
419 static const unsigned int _lh_array_tag_vt_value = 0Xfffffffd;
420 static const unsigned int _lh_array_tag_obj_value = 0Xfffffffe;
421
422 // null-free array flag bit under the array tag bits, shift one more to get array tag value
423 static const int _lh_null_free_shift = _lh_array_tag_shift - 1;
424 static const int _lh_null_free_mask = 1;
425
426 static const jint _lh_array_tag_flat_value_bit_inplace = (jint) (1 << _lh_array_tag_shift);
427
428 static int layout_helper_size_in_bytes(jint lh) {
429 assert(lh > (jint)_lh_neutral_value, "must be instance");
430 return (int) lh & ~_lh_instance_slow_path_bit;
431 }
432 static bool layout_helper_needs_slow_path(jint lh) {
433 assert(lh > (jint)_lh_neutral_value, "must be instance");
434 return (lh & _lh_instance_slow_path_bit) != 0;
435 }
436 static bool layout_helper_is_instance(jint lh) {
437 return (jint)lh > (jint)_lh_neutral_value;
438 }
439 static bool layout_helper_is_array(jint lh) {
440 return (jint)lh < (jint)_lh_neutral_value;
441 }
442 static bool layout_helper_is_typeArray(jint lh) {
443 return (juint) _lh_array_tag_type_value == (juint)(lh >> _lh_array_tag_shift);
444 }
445 static bool layout_helper_is_objArray(jint lh) {
446 return (juint)_lh_array_tag_obj_value == (juint)(lh >> _lh_array_tag_shift);
447 }
448 static bool layout_helper_is_flatArray(jint lh) {
449 return (juint)_lh_array_tag_vt_value == (juint)(lh >> _lh_array_tag_shift);
450 }
451 static bool layout_helper_is_null_free(jint lh) {
452 assert(layout_helper_is_flatArray(lh) || layout_helper_is_objArray(lh), "must be array of inline types");
453 return ((lh >> _lh_null_free_shift) & _lh_null_free_mask);
454 }
455 static jint layout_helper_set_null_free(jint lh) {
456 lh |= (_lh_null_free_mask << _lh_null_free_shift);
457 assert(layout_helper_is_null_free(lh), "Bad encoding");
458 return lh;
459 }
460 static int layout_helper_header_size(jint lh) {
461 assert(lh < (jint)_lh_neutral_value, "must be array");
462 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
463 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
464 return hsize;
465 }
466 static BasicType layout_helper_element_type(jint lh) {
467 assert(lh < (jint)_lh_neutral_value, "must be array");
468 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
469 assert((btvalue >= T_BOOLEAN && btvalue <= T_OBJECT) || btvalue == T_PRIMITIVE_OBJECT, "sanity");
470 return (BasicType) btvalue;
471 }
472
473 // Want a pattern to quickly diff against layout header in register
474 // find something less clever!
475 static int layout_helper_boolean_diffbit() {
476 jint zlh = array_layout_helper(T_BOOLEAN);
477 jint blh = array_layout_helper(T_BYTE);
478 assert(zlh != blh, "array layout helpers must differ");
479 int diffbit = 1;
480 while ((diffbit & (zlh ^ blh)) == 0 && (diffbit & zlh) == 0) {
481 diffbit <<= 1;
482 assert(diffbit != 0, "make sure T_BOOLEAN has a different bit than T_BYTE");
483 }
484 return diffbit;
485 }
486
487 static int layout_helper_log2_element_size(jint lh) {
488 assert(lh < (jint)_lh_neutral_value, "must be array");
489 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
490 assert(layout_helper_element_type(lh) == T_PRIMITIVE_OBJECT || l2esz <= LogBytesPerLong,
491 "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh);
492 return l2esz;
493 }
494 static jint array_layout_helper(jint tag, bool null_free, int hsize, BasicType etype, int log2_esize) {
495 return (tag << _lh_array_tag_shift)
496 | ((null_free ? 1 : 0) << _lh_null_free_shift)
497 | (hsize << _lh_header_size_shift)
498 | ((int)etype << _lh_element_type_shift)
499 | (log2_esize << _lh_log2_element_size_shift);
500 }
501 static jint instance_layout_helper(jint size, bool slow_path_flag) {
502 return (size << LogBytesPerWord)
503 | (slow_path_flag ? _lh_instance_slow_path_bit : 0);
504 }
505 static int layout_helper_to_size_helper(jint lh) {
506 assert(lh > (jint)_lh_neutral_value, "must be instance");
507 // Note that the following expression discards _lh_instance_slow_path_bit.
508 return lh >> LogBytesPerWord;
509 }
510 // Out-of-line version computes everything based on the etype:
511 static jint array_layout_helper(BasicType etype);
512
513 // What is the maximum number of primary superclasses any klass can have?
514 static juint primary_super_limit() { return _primary_super_limit; }
515
516 // vtables
517 klassVtable vtable() const;
518 int vtable_length() const { return _vtable_len; }
519
520 // subclass check
521 bool is_subclass_of(const Klass* k) const;
522 // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
523 bool is_subtype_of(Klass* k) const {
524 juint off = k->super_check_offset();
525 Klass* sup = *(Klass**)( (address)this + off );
526 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
527 if (sup == k) {
528 return true;
529 } else if (off != secondary_offset) {
530 return false;
531 } else {
532 return search_secondary_supers(k);
533 }
534 }
535
536 bool search_secondary_supers(Klass* k) const;
537
538 // Find LCA in class hierarchy
539 Klass *LCA( Klass *k );
540
541 // Check whether reflection/jni/jvm code is allowed to instantiate this class;
542 // if not, throw either an Error or an Exception.
543 virtual void check_valid_for_instantiation(bool throwError, TRAPS);
544
545 // array copying
546 virtual void copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
547
548 // tells if the class should be initialized
549 virtual bool should_be_initialized() const { return false; }
550 // initializes the klass
551 virtual void initialize(TRAPS);
552 virtual Klass* find_field(Symbol* name, Symbol* signature, fieldDescriptor* fd) const;
553 virtual Method* uncached_lookup_method(const Symbol* name, const Symbol* signature,
554 OverpassLookupMode overpass_mode,
555 PrivateLookupMode = PrivateLookupMode::find) const;
556 public:
557 Method* lookup_method(const Symbol* name, const Symbol* signature) const {
558 return uncached_lookup_method(name, signature, OverpassLookupMode::find);
559 }
560
561 // array class with specific rank
562 virtual ArrayKlass* array_klass(int rank, TRAPS) = 0;
563
564 // array class with this klass as element type
565 virtual ArrayKlass* array_klass(TRAPS) = 0;
566
567 // These will return null instead of allocating on the heap:
568 virtual ArrayKlass* array_klass_or_null(int rank) = 0;
569 virtual ArrayKlass* array_klass_or_null() = 0;
570
571 virtual oop protection_domain() const = 0;
572
573 oop class_loader() const;
574
575 inline oop klass_holder() const;
576
577 protected:
578
579 // Error handling when length > max_length or length < 0
580 static void check_array_allocation_length(int length, int max_length, TRAPS);
581
582 void set_vtable_length(int len) { _vtable_len= len; }
583
584 vtableEntry* start_of_vtable() const;
585 #if INCLUDE_CDS
586 void restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS);
587 #endif
588 public:
589 Method* method_at_vtable(int index);
590
591 static ByteSize vtable_start_offset();
592 static ByteSize vtable_length_offset() {
593 return byte_offset_of(Klass, _vtable_len);
594 }
595
596 #if INCLUDE_CDS
597 // CDS support - remove and restore oops from metadata. Oops are not shared.
598 virtual void remove_unshareable_info();
599 virtual void remove_java_mirror();
600
601 bool is_unshareable_info_restored() const {
602 assert(is_shared(), "use this for shared classes only");
603 if (has_archived_mirror_index()) {
604 // _java_mirror is not a valid OopHandle but rather an encoded reference in the shared heap
605 return false;
606 } else if (_java_mirror.is_empty()) {
607 return false;
608 } else {
609 return true;
610 }
611 }
612 #endif // INCLUDE_CDS
613
614 public:
615 // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
616 // These functions describe behavior for the oop not the KLASS.
617
618 // actual oop size of obj in memory in word size.
619 virtual size_t oop_size(oop obj) const = 0;
620
621 // Size of klass in word size.
622 virtual int size() const = 0;
623
624 // Returns the Java name for a class (Resource allocated)
625 // For arrays, this returns the name of the element with a leading '['.
626 // For classes, this returns the name with the package separators
627 // turned into '.'s.
628 const char* external_name() const;
629 // Returns the name for a class (Resource allocated) as the class
630 // would appear in a signature.
631 // For arrays, this returns the name of the element with a leading '['.
632 // For classes, this returns the name with a leading 'L' and a trailing ';'
633 // and the package separators as '/'.
634 virtual const char* signature_name() const;
635
636 const char* joint_in_module_of_loader(const Klass* class2, bool include_parent_loader = false) const;
637 const char* class_in_module_of_loader(bool use_are = false, bool include_parent_loader = false) const;
638
639 // Returns "interface", "abstract class" or "class".
640 const char* external_kind() const;
641
642 // type testing operations
643 #ifdef ASSERT
644 protected:
645 virtual bool is_instance_klass_slow() const { return false; }
646 virtual bool is_array_klass_slow() const { return false; }
647 virtual bool is_objArray_klass_slow() const { return false; }
648 virtual bool is_typeArray_klass_slow() const { return false; }
649 virtual bool is_flatArray_klass_slow() const { return false; }
650 #endif // ASSERT
651 // current implementation uses this method even in non debug builds
652 virtual bool is_inline_klass_slow() const { return false; }
653 public:
654
655 // Fast non-virtual versions
656 #ifndef ASSERT
657 #define assert_same_query(xval, xcheck) xval
658 #else
659 private:
660 static bool assert_same_query(bool xval, bool xslow) {
661 assert(xval == xslow, "slow and fast queries agree");
662 return xval;
663 }
664 public:
665 #endif
666
667 bool is_instance_klass() const { return assert_same_query(_kind <= InstanceStackChunkKlassKind, is_instance_klass_slow()); }
668 bool is_inline_klass() const { return assert_same_query(_kind == InlineKlassKind, is_inline_klass_slow()); }
669 bool is_reference_instance_klass() const { return _kind == InstanceRefKlassKind; }
670 bool is_mirror_instance_klass() const { return _kind == InstanceMirrorKlassKind; }
671 bool is_class_loader_instance_klass() const { return _kind == InstanceClassLoaderKlassKind; }
672 bool is_array_klass() const { return assert_same_query( _kind >= TypeArrayKlassKind, is_array_klass_slow()); }
673 bool is_stack_chunk_instance_klass() const { return _kind == InstanceStackChunkKlassKind; }
674 bool is_flatArray_klass() const { return assert_same_query( _kind == FlatArrayKlassKind, is_flatArray_klass_slow()); }
675 bool is_objArray_klass() const { return assert_same_query( _kind == ObjArrayKlassKind, is_objArray_klass_slow()); }
676 bool is_typeArray_klass() const { return assert_same_query( _kind == TypeArrayKlassKind, is_typeArray_klass_slow()); }
677 #undef assert_same_query
678
679 inline bool is_null_free_array_klass() const { return layout_helper_is_null_free(layout_helper()); }
680
681 // Access flags
682 AccessFlags access_flags() const { return _access_flags; }
683 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
684
685 bool is_public() const { return _access_flags.is_public(); }
686 bool is_final() const { return _access_flags.is_final(); }
687 bool is_interface() const { return _access_flags.is_interface(); }
688 bool is_abstract() const { return _access_flags.is_abstract(); }
689 bool is_synthetic() const { return _access_flags.is_synthetic(); }
690 bool is_identity_class() const { return _access_flags.is_identity_class(); }
691 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
692 bool has_finalizer() const { return _access_flags.has_finalizer(); }
693 void set_has_finalizer() { _access_flags.set_has_finalizer(); }
694 bool is_hidden() const { return access_flags().is_hidden_class(); }
695 void set_is_hidden() { _access_flags.set_is_hidden_class(); }
696 bool is_value_based() { return _access_flags.is_value_based_class(); }
697 void set_is_value_based() { _access_flags.set_is_value_based_class(); }
698
699 inline bool is_non_strong_hidden() const;
700
701 bool is_cloneable() const;
702 void set_is_cloneable();
703
704 // inline types and inline type array patterns
705 markWord prototype_header() const {
706 return _prototype_header;
707 }
708 static inline markWord default_prototype_header(Klass* k) {
709 return (k == nullptr) ? markWord::prototype() : k->prototype_header();
710 }
711
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
722 void clean_subklass();
723
724 static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true);
725 static void clean_subklass_tree() {
726 clean_weak_klass_links(/*unloading_occurred*/ true , /* clean_alive_klasses */ false);
727 }
728
729 // Return self, except for abstract classes with exactly 1
730 // implementor. Then return the 1 concrete implementation.
731 Klass *up_cast_abstract();
732
733 // klass name
734 Symbol* name() const { return _name; }
735 void set_name(Symbol* n);
736
737 virtual void release_C_heap_structures(bool release_constant_pool = true);
738
739 public:
740 virtual jint compute_modifier_flags() const = 0;
741
742 // JVMTI support
743 virtual jint jvmti_class_status() const;
744
745 // Printing
746 virtual void print_on(outputStream* st) const;
747
748 virtual void oop_print_value_on(oop obj, outputStream* st);
749 virtual void oop_print_on (oop obj, outputStream* st);
750
751 virtual const char* internal_name() const = 0;
752
753 // Verification
754 virtual void verify_on(outputStream* st);
755 void verify() { verify_on(tty); }
756
757 #ifndef PRODUCT
758 bool verify_vtable_index(int index);
759 #endif
760
761 virtual void oop_verify_on(oop obj, outputStream* st);
762
763 // for error reporting
764 static bool is_valid(Klass* k);
765 };
766
767 #endif // SHARE_OOPS_KLASS_HPP