1 /*
2 * Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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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 // Klass Kinds for all subclasses of Klass
41 enum KlassKind {
42 InstanceKlassKind,
43 InlineKlassKind,
44 InstanceRefKlassKind,
45 InstanceMirrorKlassKind,
46 InstanceClassLoaderKlassKind,
47 InstanceStackChunkKlassKind,
48 TypeArrayKlassKind,
49 FlatArrayKlassKind,
50 ObjArrayKlassKind
51 };
52
53 const uint KLASS_KIND_COUNT = ObjArrayKlassKind + 1;
54
55 //
56 // A Klass provides:
57 // 1: language level class object (method dictionary etc.)
58 // 2: provide vm dispatch behavior for the object
59 // Both functions are combined into one C++ class.
60
61 // One reason for the oop/klass dichotomy in the implementation is
62 // that we don't want a C++ vtbl pointer in every object. Thus,
63 // normal oops don't have any virtual functions. Instead, they
64 // forward all "virtual" functions to their klass, which does have
65 // a vtbl and does the C++ dispatch depending on the object's
66 // actual type. (See oop.inline.hpp for some of the forwarding code.)
67 // ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"!
68
69 // Forward declarations.
70 template <class T> class Array;
71 template <class T> class GrowableArray;
72 class ClassLoaderData;
73 class fieldDescriptor;
74 class klassVtable;
75 class ModuleEntry;
76 class PackageEntry;
77 class ParCompactionManager;
78 class PSPromotionManager;
79 class vtableEntry;
80
81 class Klass : public Metadata {
82 friend class VMStructs;
83 friend class JVMCIVMStructs;
84 protected:
85 // If you add a new field that points to any metaspace object, you
86 // must add this field to Klass::metaspace_pointers_do().
87
88 // note: put frequently-used fields together at start of klass structure
89 // for better cache behavior (may not make much of a difference but sure won't hurt)
90 enum { _primary_super_limit = 8 };
91
92 // The "layout helper" is a combined descriptor of object layout.
93 // For klasses which are neither instance nor array, the value is zero.
94 //
95 // For instances, layout helper is a positive number, the instance size.
96 // This size is already passed through align_object_size and scaled to bytes.
97 // The low order bit is set if instances of this class cannot be
98 // allocated using the fastpath.
99 //
100 // For arrays, layout helper is a negative number, containing four
101 // distinct bytes, as follows:
102 // MSB:[tag, hsz, ebt, log2(esz)]:LSB
103 // where:
104 // tag is 0x80 if the elements are oops, 0xC0 if non-oops, 0xA0 if value types
105 // hsz is array header size in bytes (i.e., offset of first element)
106 // ebt is the BasicType of the elements
107 // esz is the element size in bytes
108 // This packed word is arranged so as to be quickly unpacked by the
109 // various fast paths that use the various subfields.
110 //
111 // The esz bits can be used directly by a SLL instruction, without masking.
112 //
113 // Note that the array-kind tag looks like 0x00 for instance klasses,
114 // since their length in bytes is always less than 24Mb.
115 //
116 // Final note: This comes first, immediately after C++ vtable,
117 // because it is frequently queried.
118 jint _layout_helper;
119
120 // Klass kind used to resolve the runtime type of the instance.
121 // - Used to implement devirtualized oop closure dispatching.
122 // - Various type checking in the JVM
123 const KlassKind _kind;
124
125 // Processed access flags, for use by Class.getModifiers.
126 jint _modifier_flags;
127
128 // The fields _super_check_offset, _secondary_super_cache, _secondary_supers
129 // and _primary_supers all help make fast subtype checks. See big discussion
130 // in doc/server_compiler/checktype.txt
131 //
132 // Where to look to observe a supertype (it is &_secondary_super_cache for
133 // secondary supers, else is &_primary_supers[depth()].
134 juint _super_check_offset;
135
136 // Class name. Instance classes: java/lang/String, etc. Array classes: [I,
137 // [Ljava/lang/String;, etc. Set to zero for all other kinds of classes.
138 Symbol* _name;
139
140 // Cache of last observed secondary supertype
141 Klass* _secondary_super_cache;
142 // Array of all secondary supertypes
143 Array<Klass*>* _secondary_supers;
144 // Ordered list of all primary supertypes
145 Klass* _primary_supers[_primary_super_limit];
146 // java/lang/Class instance mirroring this class
147 OopHandle _java_mirror;
148 // Superclass
149 Klass* _super;
150 // First subclass (NULL if none); _subklass->next_sibling() is next one
151 Klass* volatile _subklass;
152 // Sibling link (or NULL); links all subklasses of a klass
153 Klass* volatile _next_sibling;
154
155 // All klasses loaded by a class loader are chained through these links
156 Klass* _next_link;
157
158 // The VM's representation of the ClassLoader used to load this class.
159 // Provide access the corresponding instance java.lang.ClassLoader.
160 ClassLoaderData* _class_loader_data;
161
162 int _vtable_len; // vtable length. This field may be read very often when we
163 // have lots of itable dispatches (e.g., lambdas and streams).
164 // Keep it away from the beginning of a Klass to avoid cacheline
165 // contention that may happen when a nearby object is modified.
166 AccessFlags _access_flags; // Access flags. The class/interface distinction is stored here.
167
168 JFR_ONLY(DEFINE_TRACE_ID_FIELD;)
169
170 markWord _prototype_header; // inline type and inline array mark patterns
171 private:
172 // This is an index into FileMapHeader::_shared_path_table[], to
173 // associate this class with the JAR file where it's loaded from during
174 // dump time. If a class is not loaded from the shared archive, this field is
175 // -1.
176 jshort _shared_class_path_index;
177
178 #if INCLUDE_CDS
179 // Various attributes for shared classes. Should be zero for a non-shared class.
180 u2 _shared_class_flags;
181 enum CDSSharedClassFlags {
182 _archived_lambda_proxy_is_available = 1 << 1,
183 _has_value_based_class_annotation = 1 << 2,
184 _verified_at_dump_time = 1 << 3,
185 _has_archived_enum_objs = 1 << 4,
186 // This class was not loaded from a classfile in the module image
187 // or classpath.
188 _is_generated_shared_class = 1 << 5
189 };
190 #endif
191
192 CDS_JAVA_HEAP_ONLY(int _archived_mirror_index;)
193
194 protected:
195
196 // Constructor
197 Klass(KlassKind kind);
198 Klass() : _kind(KlassKind(-1)) { assert(DumpSharedSpaces || UseSharedSpaces, "only for cds"); }
199
200 void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw();
201
202 public:
203 int kind() { return _kind; }
204
205 enum class DefaultsLookupMode { find, skip };
206 enum class OverpassLookupMode { find, skip };
207 enum class StaticLookupMode { find, skip };
208 enum class PrivateLookupMode { find, skip };
209
210 virtual bool is_klass() const { return true; }
211
212 // super() cannot be InstanceKlass* -- Java arrays are covariant, and _super is used
213 // to implement that. NB: the _super of "[Ljava/lang/Integer;" is "[Ljava/lang/Number;"
214 // If this is not what your code expects, you're probably looking for Klass::java_super().
215 Klass* super() const { return _super; }
216 void set_super(Klass* k) { _super = k; }
217
218 // initializes _super link, _primary_supers & _secondary_supers arrays
219 void initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS);
220
221 // klass-specific helper for initializing _secondary_supers
222 virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots,
223 Array<InstanceKlass*>* transitive_interfaces);
224
225 // java_super is the Java-level super type as specified by Class.getSuperClass.
226 virtual InstanceKlass* java_super() const { return NULL; }
227
228 juint super_check_offset() const { return _super_check_offset; }
229 void set_super_check_offset(juint o) { _super_check_offset = o; }
230
231 Klass* secondary_super_cache() const { return _secondary_super_cache; }
232 void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; }
233
234 Array<Klass*>* secondary_supers() const { return _secondary_supers; }
235 void set_secondary_supers(Array<Klass*>* k) { _secondary_supers = k; }
236
237 // Return the element of the _super chain of the given depth.
238 // If there is no such element, return either NULL or this.
239 Klass* primary_super_of_depth(juint i) const {
240 assert(i < primary_super_limit(), "oob");
241 Klass* super = _primary_supers[i];
242 assert(super == NULL || super->super_depth() == i, "correct display");
243 return super;
244 }
245
246 // Can this klass be a primary super? False for interfaces and arrays of
247 // interfaces. False also for arrays or classes with long super chains.
248 bool can_be_primary_super() const {
249 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
250 return super_check_offset() != secondary_offset;
251 }
252 virtual bool can_be_primary_super_slow() const;
253
254 // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit].
255 juint super_depth() const {
256 if (!can_be_primary_super()) {
257 return primary_super_limit();
258 } else {
259 juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*);
260 assert(d < primary_super_limit(), "oob");
261 assert(_primary_supers[d] == this, "proper init");
262 return d;
263 }
264 }
265
266 // java mirror
267 oop java_mirror() const;
268 oop java_mirror_no_keepalive() const;
269 void set_java_mirror(Handle m);
270
271 oop archived_java_mirror() NOT_CDS_JAVA_HEAP_RETURN_(NULL);
272 void set_archived_java_mirror(oop m) NOT_CDS_JAVA_HEAP_RETURN;
273
274 // Temporary mirror switch used by RedefineClasses
275 OopHandle java_mirror_handle() const { return _java_mirror; }
276 void swap_java_mirror_handle(OopHandle& mirror) { _java_mirror.swap(mirror); }
277
278 // Set java mirror OopHandle to NULL for CDS
279 // This leaves the OopHandle in the CLD, but that's ok, you can't release them.
280 void clear_java_mirror_handle() { _java_mirror = OopHandle(); }
281
282 // modifier flags
283 jint modifier_flags() const { return _modifier_flags; }
284 void set_modifier_flags(jint flags) { _modifier_flags = flags; }
285
286 // size helper
287 int layout_helper() const { return _layout_helper; }
288 void set_layout_helper(int lh) { _layout_helper = lh; }
289
290 // Note: for instances layout_helper() may include padding.
291 // Use InstanceKlass::contains_field_offset to classify field offsets.
292
293 // sub/superklass links
294 Klass* subklass(bool log = false) const;
295 Klass* next_sibling(bool log = false) const;
296
297 InstanceKlass* superklass() const;
298 void append_to_sibling_list(); // add newly created receiver to superklass' subklass list
299
300 void set_next_link(Klass* k) { _next_link = k; }
301 Klass* next_link() const { return _next_link; } // The next klass defined by the class loader.
302 Klass** next_link_addr() { return &_next_link; }
303
304 // class loader data
305 ClassLoaderData* class_loader_data() const { return _class_loader_data; }
306 void set_class_loader_data(ClassLoaderData* loader_data) { _class_loader_data = loader_data; }
307
308 int shared_classpath_index() const {
309 return _shared_class_path_index;
310 };
311
312 void set_shared_classpath_index(int index) {
313 _shared_class_path_index = index;
314 };
315
316 bool has_archived_mirror_index() const {
317 CDS_JAVA_HEAP_ONLY(return _archived_mirror_index >= 0;)
318 NOT_CDS_JAVA_HEAP(return false);
319 }
320
321 void clear_archived_mirror_index() NOT_CDS_JAVA_HEAP_RETURN;
322
323 void set_lambda_proxy_is_available() {
324 CDS_ONLY(_shared_class_flags |= _archived_lambda_proxy_is_available;)
325 }
326 void clear_lambda_proxy_is_available() {
327 CDS_ONLY(_shared_class_flags &= ~_archived_lambda_proxy_is_available;)
328 }
329 bool lambda_proxy_is_available() const {
330 CDS_ONLY(return (_shared_class_flags & _archived_lambda_proxy_is_available) != 0;)
331 NOT_CDS(return false;)
332 }
333
334 void set_has_value_based_class_annotation() {
335 CDS_ONLY(_shared_class_flags |= _has_value_based_class_annotation;)
336 }
337 void clear_has_value_based_class_annotation() {
338 CDS_ONLY(_shared_class_flags &= ~_has_value_based_class_annotation;)
339 }
340 bool has_value_based_class_annotation() const {
341 CDS_ONLY(return (_shared_class_flags & _has_value_based_class_annotation) != 0;)
342 NOT_CDS(return false;)
343 }
344
345 void set_verified_at_dump_time() {
346 CDS_ONLY(_shared_class_flags |= _verified_at_dump_time;)
347 }
348 bool verified_at_dump_time() const {
349 CDS_ONLY(return (_shared_class_flags & _verified_at_dump_time) != 0;)
350 NOT_CDS(return false;)
351 }
352
353 void set_has_archived_enum_objs() {
354 CDS_ONLY(_shared_class_flags |= _has_archived_enum_objs;)
355 }
356 bool has_archived_enum_objs() const {
357 CDS_ONLY(return (_shared_class_flags & _has_archived_enum_objs) != 0;)
358 NOT_CDS(return false;)
359 }
360
361 void set_is_generated_shared_class() {
362 CDS_ONLY(_shared_class_flags |= _is_generated_shared_class;)
363 }
364 bool is_generated_shared_class() const {
365 CDS_ONLY(return (_shared_class_flags & _is_generated_shared_class) != 0;)
366 NOT_CDS(return false;)
367 }
368
369 // Obtain the module or package for this class
370 virtual ModuleEntry* module() const = 0;
371 virtual PackageEntry* package() const = 0;
372
373 protected: // internal accessors
374 void set_subklass(Klass* s);
375 void set_next_sibling(Klass* s);
376
377 public:
378
379 // Compiler support
380 static ByteSize super_offset() { return in_ByteSize(offset_of(Klass, _super)); }
381 static ByteSize super_check_offset_offset() { return in_ByteSize(offset_of(Klass, _super_check_offset)); }
382 static ByteSize primary_supers_offset() { return in_ByteSize(offset_of(Klass, _primary_supers)); }
383 static ByteSize secondary_super_cache_offset() { return in_ByteSize(offset_of(Klass, _secondary_super_cache)); }
384 static ByteSize secondary_supers_offset() { return in_ByteSize(offset_of(Klass, _secondary_supers)); }
385 static ByteSize java_mirror_offset() { return in_ByteSize(offset_of(Klass, _java_mirror)); }
386 static ByteSize class_loader_data_offset() { return in_ByteSize(offset_of(Klass, _class_loader_data)); }
387 static ByteSize modifier_flags_offset() { return in_ByteSize(offset_of(Klass, _modifier_flags)); }
388 static ByteSize layout_helper_offset() { return in_ByteSize(offset_of(Klass, _layout_helper)); }
389 static ByteSize access_flags_offset() { return in_ByteSize(offset_of(Klass, _access_flags)); }
390
391 // Unpacking layout_helper:
392 static const int _lh_neutral_value = 0; // neutral non-array non-instance value
393 static const int _lh_instance_slow_path_bit = 0x01;
394 static const int _lh_log2_element_size_shift = BitsPerByte*0;
395 static const int _lh_log2_element_size_mask = BitsPerLong-1;
396 static const int _lh_element_type_shift = BitsPerByte*1;
397 static const int _lh_element_type_mask = right_n_bits(BitsPerByte); // shifted mask
398 static const int _lh_header_size_shift = BitsPerByte*2;
399 static const int _lh_header_size_mask = right_n_bits(BitsPerByte); // shifted mask
400 static const int _lh_array_tag_bits = 3;
401 static const int _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits;
402
403 static const unsigned int _lh_array_tag_type_value = 0Xfffffffc;
404 static const unsigned int _lh_array_tag_vt_value = 0Xfffffffd;
405 static const unsigned int _lh_array_tag_obj_value = 0Xfffffffe;
406
407 // null-free array flag bit under the array tag bits, shift one more to get array tag value
408 static const int _lh_null_free_shift = _lh_array_tag_shift - 1;
409 static const int _lh_null_free_mask = 1;
410
411 static const jint _lh_array_tag_flat_value_bit_inplace = (jint) (1 << _lh_array_tag_shift);
412 static const jint _lh_null_free_array_bit_inplace = (jint) (_lh_null_free_mask << _lh_null_free_shift);
413
414 static int layout_helper_size_in_bytes(jint lh) {
415 assert(lh > (jint)_lh_neutral_value, "must be instance");
416 return (int) lh & ~_lh_instance_slow_path_bit;
417 }
418 static bool layout_helper_needs_slow_path(jint lh) {
419 assert(lh > (jint)_lh_neutral_value, "must be instance");
420 return (lh & _lh_instance_slow_path_bit) != 0;
421 }
422 static bool layout_helper_is_instance(jint lh) {
423 return (jint)lh > (jint)_lh_neutral_value;
424 }
425 static bool layout_helper_is_array(jint lh) {
426 return (jint)lh < (jint)_lh_neutral_value;
427 }
428 static bool layout_helper_is_typeArray(jint lh) {
429 return (juint) _lh_array_tag_type_value == (juint)(lh >> _lh_array_tag_shift);
430 }
431 static bool layout_helper_is_objArray(jint lh) {
432 return (juint)_lh_array_tag_obj_value == (juint)(lh >> _lh_array_tag_shift);
433 }
434 static bool layout_helper_is_flatArray(jint lh) {
435 return (juint)_lh_array_tag_vt_value == (juint)(lh >> _lh_array_tag_shift);
436 }
437 static bool layout_helper_is_null_free(jint lh) {
438 assert(layout_helper_is_flatArray(lh) || layout_helper_is_objArray(lh), "must be array of inline types");
439 return ((lh >> _lh_null_free_shift) & _lh_null_free_mask);
440 }
441 static jint layout_helper_set_null_free(jint lh) {
442 lh |= (_lh_null_free_mask << _lh_null_free_shift);
443 assert(layout_helper_is_null_free(lh), "Bad encoding");
444 return lh;
445 }
446 static int layout_helper_header_size(jint lh) {
447 assert(lh < (jint)_lh_neutral_value, "must be array");
448 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
449 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
450 return hsize;
451 }
452 static BasicType layout_helper_element_type(jint lh) {
453 assert(lh < (jint)_lh_neutral_value, "must be array");
454 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
455 assert((btvalue >= T_BOOLEAN && btvalue <= T_OBJECT) || btvalue == T_PRIMITIVE_OBJECT, "sanity");
456 return (BasicType) btvalue;
457 }
458
459 // Want a pattern to quickly diff against layout header in register
460 // find something less clever!
461 static int layout_helper_boolean_diffbit() {
462 jint zlh = array_layout_helper(T_BOOLEAN);
463 jint blh = array_layout_helper(T_BYTE);
464 assert(zlh != blh, "array layout helpers must differ");
465 int diffbit = 1;
466 while ((diffbit & (zlh ^ blh)) == 0 && (diffbit & zlh) == 0) {
467 diffbit <<= 1;
468 assert(diffbit != 0, "make sure T_BOOLEAN has a different bit than T_BYTE");
469 }
470 return diffbit;
471 }
472
473 static int layout_helper_log2_element_size(jint lh) {
474 assert(lh < (jint)_lh_neutral_value, "must be array");
475 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
476 assert(layout_helper_element_type(lh) == T_PRIMITIVE_OBJECT || l2esz <= LogBytesPerLong,
477 "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh);
478 return l2esz;
479 }
480 static jint array_layout_helper(jint tag, bool null_free, int hsize, BasicType etype, int log2_esize) {
481 return (tag << _lh_array_tag_shift)
482 | ((null_free ? 1 : 0) << _lh_null_free_shift)
483 | (hsize << _lh_header_size_shift)
484 | ((int)etype << _lh_element_type_shift)
485 | (log2_esize << _lh_log2_element_size_shift);
486 }
487 static jint instance_layout_helper(jint size, bool slow_path_flag) {
488 return (size << LogBytesPerWord)
489 | (slow_path_flag ? _lh_instance_slow_path_bit : 0);
490 }
491 static int layout_helper_to_size_helper(jint lh) {
492 assert(lh > (jint)_lh_neutral_value, "must be instance");
493 // Note that the following expression discards _lh_instance_slow_path_bit.
494 return lh >> LogBytesPerWord;
495 }
496 // Out-of-line version computes everything based on the etype:
497 static jint array_layout_helper(BasicType etype);
498
499 // What is the maximum number of primary superclasses any klass can have?
500 static juint primary_super_limit() { return _primary_super_limit; }
501
502 // vtables
503 klassVtable vtable() const;
504 int vtable_length() const { return _vtable_len; }
505
506 // subclass check
507 bool is_subclass_of(const Klass* k) const;
508 // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
509 bool is_subtype_of(Klass* k) const {
510 juint off = k->super_check_offset();
511 Klass* sup = *(Klass**)( (address)this + off );
512 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
513 if (sup == k) {
514 return true;
515 } else if (off != secondary_offset) {
516 return false;
517 } else {
518 return search_secondary_supers(k);
519 }
520 }
521
522 bool search_secondary_supers(Klass* k) const;
523
524 // Find LCA in class hierarchy
525 Klass *LCA( Klass *k );
526
527 // Check whether reflection/jni/jvm code is allowed to instantiate this class;
528 // if not, throw either an Error or an Exception.
529 virtual void check_valid_for_instantiation(bool throwError, TRAPS);
530
531 // array copying
532 virtual void copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
533
534 // tells if the class should be initialized
535 virtual bool should_be_initialized() const { return false; }
536 // initializes the klass
537 virtual void initialize(TRAPS);
538 virtual Klass* find_field(Symbol* name, Symbol* signature, fieldDescriptor* fd) const;
539 virtual Method* uncached_lookup_method(const Symbol* name, const Symbol* signature,
540 OverpassLookupMode overpass_mode,
541 PrivateLookupMode = PrivateLookupMode::find) const;
542 public:
543 Method* lookup_method(const Symbol* name, const Symbol* signature) const {
544 return uncached_lookup_method(name, signature, OverpassLookupMode::find);
545 }
546
547 // array class with specific rank
548 virtual Klass* array_klass(int rank, TRAPS) = 0;
549
550 // array class with this klass as element type
551 virtual Klass* array_klass(TRAPS) = 0;
552
553 // These will return NULL instead of allocating on the heap:
554 virtual Klass* array_klass_or_null(int rank) = 0;
555 virtual Klass* array_klass_or_null() = 0;
556
557 virtual oop protection_domain() const = 0;
558
559 oop class_loader() const;
560
561 inline oop klass_holder() const;
562
563 protected:
564
565 // Error handling when length > max_length or length < 0
566 static void check_array_allocation_length(int length, int max_length, TRAPS);
567
568 void set_vtable_length(int len) { _vtable_len= len; }
569
570 vtableEntry* start_of_vtable() const;
571 #if INCLUDE_CDS
572 void restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS);
573 #endif
574 public:
575 Method* method_at_vtable(int index);
576
577 static ByteSize vtable_start_offset();
578 static ByteSize vtable_length_offset() {
579 return byte_offset_of(Klass, _vtable_len);
580 }
581
582 #if INCLUDE_CDS
583 // CDS support - remove and restore oops from metadata. Oops are not shared.
584 virtual void remove_unshareable_info();
585 virtual void remove_java_mirror();
586
587 bool is_unshareable_info_restored() const {
588 assert(is_shared(), "use this for shared classes only");
589 if (has_archived_mirror_index()) {
590 // _java_mirror is not a valid OopHandle but rather an encoded reference in the shared heap
591 return false;
592 } else if (_java_mirror.ptr_raw() == NULL) {
593 return false;
594 } else {
595 return true;
596 }
597 }
598 #endif // INCLUDE_CDS
599
600 public:
601 // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
602 // These functions describe behavior for the oop not the KLASS.
603
604 // actual oop size of obj in memory in word size.
605 virtual size_t oop_size(oop obj) const = 0;
606
607 // Size of klass in word size.
608 virtual int size() const = 0;
609
610 // Returns the Java name for a class (Resource allocated)
611 // For arrays, this returns the name of the element with a leading '['.
612 // For classes, this returns the name with the package separators
613 // turned into '.'s.
614 const char* external_name() const;
615 // Returns the name for a class (Resource allocated) as the class
616 // would appear in a signature.
617 // For arrays, this returns the name of the element with a leading '['.
618 // For classes, this returns the name with a leading 'L' and a trailing ';'
619 // and the package separators as '/'.
620 virtual const char* signature_name() const;
621
622 const char* joint_in_module_of_loader(const Klass* class2, bool include_parent_loader = false) const;
623 const char* class_in_module_of_loader(bool use_are = false, bool include_parent_loader = false) const;
624
625 // Returns "interface", "abstract class" or "class".
626 const char* external_kind() const;
627
628 // type testing operations
629 #ifdef ASSERT
630 protected:
631 virtual bool is_instance_klass_slow() const { return false; }
632 virtual bool is_array_klass_slow() const { return false; }
633 virtual bool is_objArray_klass_slow() const { return false; }
634 virtual bool is_typeArray_klass_slow() const { return false; }
635 virtual bool is_flatArray_klass_slow() const { return false; }
636 #endif // ASSERT
637 // current implementation uses this method even in non debug builds
638 virtual bool is_inline_klass_slow() const { return false; }
639 public:
640
641 // Fast non-virtual versions
642 #ifndef ASSERT
643 #define assert_same_query(xval, xcheck) xval
644 #else
645 private:
646 static bool assert_same_query(bool xval, bool xslow) {
647 assert(xval == xslow, "slow and fast queries agree");
648 return xval;
649 }
650 public:
651 #endif
652
653 bool is_instance_klass() const { return assert_same_query(_kind <= InstanceStackChunkKlassKind, is_instance_klass_slow()); }
654 bool is_inline_klass() const { return is_inline_klass_slow(); } //temporary hack
655 // Other is anything that is not one of the more specialized kinds of InstanceKlass.
656 bool is_other_instance_klass() const { return _kind <= InlineKlassKind; }
657 bool is_reference_instance_klass() const { return _kind == InstanceRefKlassKind; }
658 bool is_mirror_instance_klass() const { return _kind == InstanceMirrorKlassKind; }
659 bool is_class_loader_instance_klass() const { return _kind == InstanceClassLoaderKlassKind; }
660 bool is_array_klass() const { return assert_same_query( _kind >= TypeArrayKlassKind, is_array_klass_slow()); }
661 bool is_stack_chunk_instance_klass() const { return _kind == InstanceStackChunkKlassKind; }
662 bool is_flatArray_klass() const { return assert_same_query( _kind == FlatArrayKlassKind, is_flatArray_klass_slow()); }
663 bool is_objArray_klass() const { return assert_same_query( _kind == ObjArrayKlassKind, is_objArray_klass_slow()); }
664 bool is_typeArray_klass() const { return assert_same_query( _kind == TypeArrayKlassKind, is_typeArray_klass_slow()); }
665 #undef assert_same_query
666
667 inline bool is_null_free_array_klass() const { return layout_helper_is_null_free(layout_helper()); }
668
669 // Access flags
670 AccessFlags access_flags() const { return _access_flags; }
671 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
672
673 bool is_public() const { return _access_flags.is_public(); }
674 bool is_final() const { return _access_flags.is_final(); }
675 bool is_interface() const { return _access_flags.is_interface(); }
676 bool is_abstract() const { return _access_flags.is_abstract(); }
677 bool is_synthetic() const { return _access_flags.is_synthetic(); }
678 bool is_value_class() const { return _access_flags.is_value_class(); }
679 bool is_identity_class() const { return _access_flags.is_identity_class(); }
680 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
681 bool has_finalizer() const { return _access_flags.has_finalizer(); }
682 bool has_final_method() const { return _access_flags.has_final_method(); }
683 void set_has_finalizer() { _access_flags.set_has_finalizer(); }
684 void set_has_final_method() { _access_flags.set_has_final_method(); }
685 bool has_vanilla_constructor() const { return _access_flags.has_vanilla_constructor(); }
686 void set_has_vanilla_constructor() { _access_flags.set_has_vanilla_constructor(); }
687 bool has_miranda_methods () const { return access_flags().has_miranda_methods(); }
688 void set_has_miranda_methods() { _access_flags.set_has_miranda_methods(); }
689 bool is_shared() const { return access_flags().is_shared_class(); } // shadows MetaspaceObj::is_shared)()
690 void set_is_shared() { _access_flags.set_is_shared_class(); }
691 bool is_hidden() const { return access_flags().is_hidden_class(); }
692 void set_is_hidden() { _access_flags.set_is_hidden_class(); }
693 bool is_value_based() { return _access_flags.is_value_based_class(); }
694 void set_is_value_based() { _access_flags.set_is_value_based_class(); }
695
696 inline bool is_non_strong_hidden() const;
697
698 bool is_cloneable() const;
699 void set_is_cloneable();
700
701 // inline types and inline type array patterns
702 markWord prototype_header() const {
703 return _prototype_header;
704 }
705 static inline markWord default_prototype_header(Klass* k) {
706 return (k == NULL) ? markWord::prototype() : k->prototype_header();
707 }
708
709 inline void set_prototype_header(markWord header);
710 static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); }
711
712 JFR_ONLY(DEFINE_TRACE_ID_METHODS;)
713
714 virtual void metaspace_pointers_do(MetaspaceClosure* iter);
715 virtual MetaspaceObj::Type type() const { return ClassType; }
716
717 inline bool is_loader_alive() const;
718
719 void clean_subklass();
720
721 static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true);
722 static void clean_subklass_tree() {
723 clean_weak_klass_links(/*unloading_occurred*/ true , /* clean_alive_klasses */ false);
724 }
725
726 // Return self, except for abstract classes with exactly 1
727 // implementor. Then return the 1 concrete implementation.
728 Klass *up_cast_abstract();
729
730 // klass name
731 Symbol* name() const { return _name; }
732 void set_name(Symbol* n);
733
734 virtual void release_C_heap_structures(bool release_constant_pool = true);
735
736 public:
737 virtual jint compute_modifier_flags() const = 0;
738
739 // JVMTI support
740 virtual jint jvmti_class_status() const;
741
742 // Printing
743 virtual void print_on(outputStream* st) const;
744
745 virtual void oop_print_value_on(oop obj, outputStream* st);
746 virtual void oop_print_on (oop obj, outputStream* st);
747
748 virtual const char* internal_name() const = 0;
749
750 // Verification
751 virtual void verify_on(outputStream* st);
752 void verify() { verify_on(tty); }
753
754 #ifndef PRODUCT
755 bool verify_vtable_index(int index);
756 #endif
757
758 virtual void oop_verify_on(oop obj, outputStream* st);
759
760 // for error reporting
761 static bool is_valid(Klass* k);
762 };
763
764 #endif // SHARE_OOPS_KLASS_HPP