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 *
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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
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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 markWord _prototype_header; // Used to initialize objects' header
169
170 int _vtable_len; // vtable length. This field may be read very often when we
171 // have lots of itable dispatches (e.g., lambdas and streams).
172 // Keep it away from the beginning of a Klass to avoid cacheline
173 // contention that may happen when a nearby object is modified.
174 AccessFlags _access_flags; // Access flags. The class/interface distinction is stored here.
175 // Some flags created by the JVM, not in the class file itself,
176 // are in _misc_flags below.
177
178 JFR_ONLY(DEFINE_TRACE_ID_FIELD;)
179
180 private:
181 // This is an index into FileMapHeader::_shared_path_table[], to
182 // associate this class with the JAR file where it's loaded from during
183 // dump time. If a class is not loaded from the shared archive, this field is
184 // -1.
185 s2 _shared_class_path_index;
186
187 #if INCLUDE_CDS
188 // Various attributes for shared classes. Should be zero for a non-shared class.
189 u2 _shared_class_flags;
190 enum CDSSharedClassFlags {
191 _is_shared_class = 1 << 0, // shadows MetaspaceObj::is_shared
192 _archived_lambda_proxy_is_available = 1 << 1,
193 _has_value_based_class_annotation = 1 << 2,
194 _verified_at_dump_time = 1 << 3,
195 _has_archived_enum_objs = 1 << 4,
196 // This class was not loaded from a classfile in the module image
197 // or classpath.
198 _is_generated_shared_class = 1 << 5,
199 // archived mirror already initialized by AOT-cache assembly: no further need to call <clinit>
200 _has_aot_initialized_mirror = 1 << 6,
201 // If this class has been aot-inititalized, do we need to call its runtimeSetup()
202 // method during the production run?
203 _is_runtime_setup_required = 1 << 7,
204 };
205 #endif
206
207 KlassFlags _misc_flags;
208
209 CDS_JAVA_HEAP_ONLY(int _archived_mirror_index;)
210
211 protected:
212
213 Klass(KlassKind kind);
214 Klass();
215
216 public:
217 int kind() { return _kind; }
218
219 enum class DefaultsLookupMode { find, skip };
220 enum class OverpassLookupMode { find, skip };
221 enum class StaticLookupMode { find, skip };
222 enum class PrivateLookupMode { find, skip };
223
224 virtual bool is_klass() const { return true; }
225
226 // super() cannot be InstanceKlass* -- Java arrays are covariant, and _super is used
227 // to implement that. NB: the _super of "[Ljava/lang/Integer;" is "[Ljava/lang/Number;"
228 // If this is not what your code expects, you're probably looking for Klass::java_super().
229 Klass* super() const { return _super; }
230 void set_super(Klass* k) { _super = k; }
231
232 // initializes _super link, _primary_supers & _secondary_supers arrays
233 void initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS);
234
235 // klass-specific helper for initializing _secondary_supers
236 virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots,
237 Array<InstanceKlass*>* transitive_interfaces);
238
239 // java_super is the Java-level super type as specified by Class.getSuperClass.
240 virtual InstanceKlass* java_super() const { return nullptr; }
241
242 juint super_check_offset() const { return _super_check_offset; }
243 void set_super_check_offset(juint o) { _super_check_offset = o; }
244
245 Klass* secondary_super_cache() const { return _secondary_super_cache; }
246 void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; }
247
248 Array<Klass*>* secondary_supers() const { return _secondary_supers; }
249 void set_secondary_supers(Array<Klass*>* k, uintx bitmap);
250
251 uint8_t hash_slot() const { return _hash_slot; }
252
253 // Return the element of the _super chain of the given depth.
254 // If there is no such element, return either null or this.
255 Klass* primary_super_of_depth(juint i) const {
256 assert(i < primary_super_limit(), "oob");
257 Klass* super = _primary_supers[i];
258 assert(super == nullptr || super->super_depth() == i, "correct display");
259 return super;
260 }
261
262 // Can this klass be a primary super? False for interfaces and arrays of
263 // interfaces. False also for arrays or classes with long super chains.
264 bool can_be_primary_super() const {
265 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
266 return super_check_offset() != secondary_offset;
267 }
268 virtual bool can_be_primary_super_slow() const;
269
270 // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit].
271 juint super_depth() const {
272 if (!can_be_primary_super()) {
273 return primary_super_limit();
274 } else {
275 juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*);
276 assert(d < primary_super_limit(), "oob");
277 assert(_primary_supers[d] == this, "proper init");
278 return d;
279 }
280 }
281
282 // java mirror
283 oop java_mirror() const;
284 oop java_mirror_no_keepalive() const;
285 void set_java_mirror(Handle m);
286
287 oop archived_java_mirror() NOT_CDS_JAVA_HEAP_RETURN_(nullptr);
288 void set_archived_java_mirror(int mirror_index) NOT_CDS_JAVA_HEAP_RETURN;
289
290 // Temporary mirror switch used by RedefineClasses
291 OopHandle java_mirror_handle() const { return _java_mirror; }
292 void swap_java_mirror_handle(OopHandle& mirror) { _java_mirror.swap(mirror); }
293
294 // Set java mirror OopHandle to null for CDS
295 // This leaves the OopHandle in the CLD, but that's ok, you can't release them.
296 void clear_java_mirror_handle() { _java_mirror = OopHandle(); }
297
298 // modifier flags
299 jint modifier_flags() const { return _modifier_flags; }
300 void set_modifier_flags(jint flags) { _modifier_flags = flags; }
301
302 // size helper
303 int layout_helper() const { return _layout_helper; }
304 void set_layout_helper(int lh) { _layout_helper = lh; }
305
306 // Note: for instances layout_helper() may include padding.
307 // Use InstanceKlass::contains_field_offset to classify field offsets.
308
309 // sub/superklass links
310 Klass* subklass(bool log = false) const;
311 Klass* next_sibling(bool log = false) const;
312
313 InstanceKlass* superklass() const;
314 void append_to_sibling_list(); // add newly created receiver to superklass' subklass list
315
316 void set_next_link(Klass* k) { _next_link = k; }
317 Klass* next_link() const { return _next_link; } // The next klass defined by the class loader.
318 Klass** next_link_addr() { return &_next_link; }
319
320 // class loader data
321 ClassLoaderData* class_loader_data() const { return _class_loader_data; }
322 void set_class_loader_data(ClassLoaderData* loader_data) { _class_loader_data = loader_data; }
323
324 s2 shared_classpath_index() const {
325 return _shared_class_path_index;
326 };
327
328 void set_shared_classpath_index(s2 index) {
329 _shared_class_path_index = index;
330 };
331
332 bool has_archived_mirror_index() const {
333 CDS_JAVA_HEAP_ONLY(return _archived_mirror_index >= 0;)
334 NOT_CDS_JAVA_HEAP(return false);
335 }
336
337 void clear_archived_mirror_index() NOT_CDS_JAVA_HEAP_RETURN;
338
339 void set_lambda_proxy_is_available() {
340 CDS_ONLY(_shared_class_flags |= _archived_lambda_proxy_is_available;)
341 }
342 void clear_lambda_proxy_is_available() {
343 CDS_ONLY(_shared_class_flags &= (u2)(~_archived_lambda_proxy_is_available);)
344 }
345 bool lambda_proxy_is_available() const {
346 CDS_ONLY(return (_shared_class_flags & _archived_lambda_proxy_is_available) != 0;)
347 NOT_CDS(return false;)
348 }
349
350 void set_has_value_based_class_annotation() {
351 CDS_ONLY(_shared_class_flags |= _has_value_based_class_annotation;)
352 }
353 void clear_has_value_based_class_annotation() {
354 CDS_ONLY(_shared_class_flags &= (u2)(~_has_value_based_class_annotation);)
355 }
356 bool has_value_based_class_annotation() const {
357 CDS_ONLY(return (_shared_class_flags & _has_value_based_class_annotation) != 0;)
358 NOT_CDS(return false;)
359 }
360
361 void set_verified_at_dump_time() {
362 CDS_ONLY(_shared_class_flags |= _verified_at_dump_time;)
363 }
364 bool verified_at_dump_time() const {
365 CDS_ONLY(return (_shared_class_flags & _verified_at_dump_time) != 0;)
366 NOT_CDS(return false;)
367 }
368
369 void set_has_archived_enum_objs() {
370 CDS_ONLY(_shared_class_flags |= _has_archived_enum_objs;)
371 }
372 bool has_archived_enum_objs() const {
373 CDS_ONLY(return (_shared_class_flags & _has_archived_enum_objs) != 0;)
374 NOT_CDS(return false;)
375 }
376
377 void set_is_generated_shared_class() {
378 CDS_ONLY(_shared_class_flags |= _is_generated_shared_class;)
379 }
380 bool is_generated_shared_class() const {
381 CDS_ONLY(return (_shared_class_flags & _is_generated_shared_class) != 0;)
382 NOT_CDS(return false;)
383 }
384
385 void set_has_aot_initialized_mirror() {
386 CDS_ONLY(_shared_class_flags |= _has_aot_initialized_mirror;)
387 }
388 bool has_aot_initialized_mirror() const {
389 CDS_ONLY(return (_shared_class_flags & _has_aot_initialized_mirror) != 0;)
390 NOT_CDS(return false;)
391 }
392
393 void set_is_runtime_setup_required() {
394 assert(has_aot_initialized_mirror(), "sanity");
395 CDS_ONLY(_shared_class_flags |= _is_runtime_setup_required;)
396 }
397 bool is_runtime_setup_required() const {
398 CDS_ONLY(return (_shared_class_flags & _is_runtime_setup_required) != 0;)
399 NOT_CDS(return false;)
400 }
401
402 bool is_shared() const { // shadows MetaspaceObj::is_shared)()
403 CDS_ONLY(return (_shared_class_flags & _is_shared_class) != 0;)
404 NOT_CDS(return false;)
405 }
406
407 void set_is_shared() {
408 CDS_ONLY(_shared_class_flags |= _is_shared_class;)
409 }
410
411 // Obtain the module or package for this class
412 virtual ModuleEntry* module() const = 0;
413 virtual PackageEntry* package() const = 0;
414
415 protected: // internal accessors
416 void set_subklass(Klass* s);
417 void set_next_sibling(Klass* s);
418
419 private:
420 static uint8_t compute_hash_slot(Symbol* s);
421 static void hash_insert(Klass* klass, GrowableArray<Klass*>* secondaries, uintx& bitmap);
422 static uintx hash_secondary_supers(Array<Klass*>* secondaries, bool rewrite);
423
424 bool search_secondary_supers(Klass* k) const;
425 bool lookup_secondary_supers_table(Klass *k) const;
426 bool linear_search_secondary_supers(const Klass* k) const;
427 bool fallback_search_secondary_supers(const Klass* k, int index, uintx rotated_bitmap) const;
428
429 public:
430 // Secondary supers table support
431 static Array<Klass*>* pack_secondary_supers(ClassLoaderData* loader_data,
432 GrowableArray<Klass*>* primaries,
433 GrowableArray<Klass*>* secondaries,
434 uintx& bitmap,
435 TRAPS);
436
437 static uintx compute_secondary_supers_bitmap(Array<Klass*>* secondary_supers);
438 static uint8_t compute_home_slot(Klass* k, uintx bitmap);
439
440 static constexpr int SECONDARY_SUPERS_TABLE_SIZE = sizeof(_secondary_supers_bitmap) * 8;
441 static constexpr int SECONDARY_SUPERS_TABLE_MASK = SECONDARY_SUPERS_TABLE_SIZE - 1;
442
443 static constexpr uintx SECONDARY_SUPERS_BITMAP_EMPTY = 0;
444 static constexpr uintx SECONDARY_SUPERS_BITMAP_FULL = ~(uintx)0;
445
446 // Compiler support
447 static ByteSize super_offset() { return byte_offset_of(Klass, _super); }
448 static ByteSize super_check_offset_offset() { return byte_offset_of(Klass, _super_check_offset); }
449 static ByteSize primary_supers_offset() { return byte_offset_of(Klass, _primary_supers); }
450 static ByteSize secondary_super_cache_offset() { return byte_offset_of(Klass, _secondary_super_cache); }
451 static ByteSize secondary_supers_offset() { return byte_offset_of(Klass, _secondary_supers); }
452 static ByteSize java_mirror_offset() { return byte_offset_of(Klass, _java_mirror); }
453 static ByteSize class_loader_data_offset() { return byte_offset_of(Klass, _class_loader_data); }
454 static ByteSize modifier_flags_offset() { return byte_offset_of(Klass, _modifier_flags); }
455 static ByteSize layout_helper_offset() { return byte_offset_of(Klass, _layout_helper); }
456 static ByteSize access_flags_offset() { return byte_offset_of(Klass, _access_flags); }
457 #if INCLUDE_JVMCI
458 static ByteSize subklass_offset() { return byte_offset_of(Klass, _subklass); }
459 static ByteSize next_sibling_offset() { return byte_offset_of(Klass, _next_sibling); }
460 #endif
461 static ByteSize secondary_supers_bitmap_offset()
462 { return byte_offset_of(Klass, _secondary_supers_bitmap); }
463 static ByteSize hash_slot_offset() { return byte_offset_of(Klass, _hash_slot); }
464 static ByteSize misc_flags_offset() { return byte_offset_of(Klass, _misc_flags._flags); }
465
466 // Unpacking layout_helper:
467 static const int _lh_neutral_value = 0; // neutral non-array non-instance value
468 static const int _lh_instance_slow_path_bit = 0x01;
469 static const int _lh_log2_element_size_shift = BitsPerByte*0;
470 static const int _lh_log2_element_size_mask = BitsPerLong-1;
471 static const int _lh_element_type_shift = BitsPerByte*1;
472 static const int _lh_element_type_mask = right_n_bits(BitsPerByte); // shifted mask
473 static const int _lh_header_size_shift = BitsPerByte*2;
474 static const int _lh_header_size_mask = right_n_bits(BitsPerByte); // shifted mask
475 static const int _lh_array_tag_bits = 2;
476 static const int _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits;
477 static const int _lh_array_tag_obj_value = ~0x01; // 0x80000000 >> 30
478
479 static const unsigned int _lh_array_tag_type_value = 0Xffffffff; // ~0x00, // 0xC0000000 >> 30
480
481 static int layout_helper_size_in_bytes(jint lh) {
482 assert(lh > (jint)_lh_neutral_value, "must be instance");
483 return (int) lh & ~_lh_instance_slow_path_bit;
484 }
485 static bool layout_helper_needs_slow_path(jint lh) {
486 assert(lh > (jint)_lh_neutral_value, "must be instance");
487 return (lh & _lh_instance_slow_path_bit) != 0;
488 }
489 static bool layout_helper_is_instance(jint lh) {
490 return (jint)lh > (jint)_lh_neutral_value;
491 }
492 static bool layout_helper_is_array(jint lh) {
493 return (jint)lh < (jint)_lh_neutral_value;
494 }
495 static bool layout_helper_is_typeArray(jint lh) {
496 // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
497 return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
498 }
499 static bool layout_helper_is_objArray(jint lh) {
500 // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
501 return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
502 }
503 static int layout_helper_header_size(jint lh) {
504 assert(lh < (jint)_lh_neutral_value, "must be array");
505 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
506 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
507 return hsize;
508 }
509 static BasicType layout_helper_element_type(jint lh) {
510 assert(lh < (jint)_lh_neutral_value, "must be array");
511 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
512 assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
513 return (BasicType) btvalue;
514 }
515
516 // Want a pattern to quickly diff against layout header in register
517 // find something less clever!
518 static int layout_helper_boolean_diffbit() {
519 jint zlh = array_layout_helper(T_BOOLEAN);
520 jint blh = array_layout_helper(T_BYTE);
521 assert(zlh != blh, "array layout helpers must differ");
522 int diffbit = 1;
523 while ((diffbit & (zlh ^ blh)) == 0 && (diffbit & zlh) == 0) {
524 diffbit <<= 1;
525 assert(diffbit != 0, "make sure T_BOOLEAN has a different bit than T_BYTE");
526 }
527 return diffbit;
528 }
529
530 static int layout_helper_log2_element_size(jint lh) {
531 assert(lh < (jint)_lh_neutral_value, "must be array");
532 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
533 assert(l2esz <= LogBytesPerLong,
534 "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh);
535 return l2esz;
536 }
537 static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
538 return (tag << _lh_array_tag_shift)
539 | (hsize << _lh_header_size_shift)
540 | ((int)etype << _lh_element_type_shift)
541 | (log2_esize << _lh_log2_element_size_shift);
542 }
543 static jint instance_layout_helper(jint size, bool slow_path_flag) {
544 return (size << LogBytesPerWord)
545 | (slow_path_flag ? _lh_instance_slow_path_bit : 0);
546 }
547 static int layout_helper_to_size_helper(jint lh) {
548 assert(lh > (jint)_lh_neutral_value, "must be instance");
549 // Note that the following expression discards _lh_instance_slow_path_bit.
550 return lh >> LogBytesPerWord;
551 }
552 // Out-of-line version computes everything based on the etype:
553 static jint array_layout_helper(BasicType etype);
554
555 // What is the maximum number of primary superclasses any klass can have?
556 static juint primary_super_limit() { return _primary_super_limit; }
557
558 // vtables
559 klassVtable vtable() const;
560 int vtable_length() const { return _vtable_len; }
561
562 // subclass check
563 bool is_subclass_of(const Klass* k) const;
564
565 // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
566 bool is_subtype_of(Klass* k) const;
567
568 public:
569 // Find LCA in class hierarchy
570 Klass *LCA( Klass *k );
571
572 // Check whether reflection/jni/jvm code is allowed to instantiate this class;
573 // if not, throw either an Error or an Exception.
574 virtual void check_valid_for_instantiation(bool throwError, TRAPS);
575
576 // array copying
577 virtual void copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
578
579 // tells if the class should be initialized
580 virtual bool should_be_initialized() const { return false; }
581 // initializes the klass
582 virtual void initialize(TRAPS);
583 virtual Klass* find_field(Symbol* name, Symbol* signature, fieldDescriptor* fd) const;
584 virtual Method* uncached_lookup_method(const Symbol* name, const Symbol* signature,
585 OverpassLookupMode overpass_mode,
586 PrivateLookupMode = PrivateLookupMode::find) const;
587 public:
588 Method* lookup_method(const Symbol* name, const Symbol* signature) const {
589 return uncached_lookup_method(name, signature, OverpassLookupMode::find);
590 }
591
592 // array class with specific rank
593 virtual ArrayKlass* array_klass(int rank, TRAPS) = 0;
594
595 // array class with this klass as element type
596 virtual ArrayKlass* array_klass(TRAPS) = 0;
597
598 // These will return null instead of allocating on the heap:
599 virtual ArrayKlass* array_klass_or_null(int rank) = 0;
600 virtual ArrayKlass* array_klass_or_null() = 0;
601
602 virtual oop protection_domain() const = 0;
603
604 oop class_loader() const;
605 Symbol* class_loader_name_and_id() const;
606
607 inline oop klass_holder() const;
608
609 inline void keep_alive() const;
610
611 protected:
612
613 // Error handling when length > max_length or length < 0
614 static void check_array_allocation_length(int length, int max_length, TRAPS);
615
616 void set_vtable_length(int len) { _vtable_len= len; }
617
618 vtableEntry* start_of_vtable() const;
619 #if INCLUDE_CDS
620 void restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS);
621 #endif
622 public:
623 Method* method_at_vtable(int index);
624
625 static ByteSize vtable_start_offset();
626 static ByteSize vtable_length_offset() {
627 return byte_offset_of(Klass, _vtable_len);
628 }
629
630 #if INCLUDE_CDS
631 // CDS support - remove and restore oops from metadata. Oops are not shared.
632 virtual void remove_unshareable_info();
633 virtual void remove_java_mirror();
634
635 bool is_unshareable_info_restored() const {
636 assert(is_shared(), "use this for shared classes only");
637 if (has_archived_mirror_index()) {
638 // _java_mirror is not a valid OopHandle but rather an encoded reference in the shared heap
639 return false;
640 } else if (_java_mirror.is_empty()) {
641 return false;
642 } else {
643 return true;
644 }
645 }
646 #endif // INCLUDE_CDS
647
648 public:
649 // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
650 // These functions describe behavior for the oop not the KLASS.
651
652 // actual oop size of obj in memory in word size.
653 virtual size_t oop_size(oop obj) const = 0;
654
655 // Size of klass in word size.
656 virtual int size() const = 0;
657
658 // Returns the Java name for a class (Resource allocated)
659 // For arrays, this returns the name of the element with a leading '['.
660 // For classes, this returns the name with the package separators
661 // turned into '.'s.
662 const char* external_name() const;
663 // Returns the name for a class (Resource allocated) as the class
664 // would appear in a signature.
665 // For arrays, this returns the name of the element with a leading '['.
666 // For classes, this returns the name with a leading 'L' and a trailing ';'
667 // and the package separators as '/'.
668 virtual const char* signature_name() const;
669
670 const char* joint_in_module_of_loader(const Klass* class2, bool include_parent_loader = false) const;
671 const char* class_in_module_of_loader(bool use_are = false, bool include_parent_loader = false) const;
672
673 // Returns "interface", "abstract class" or "class".
674 const char* external_kind() const;
675
676 // type testing operations
677 #ifdef ASSERT
678 protected:
679 virtual bool is_instance_klass_slow() const { return false; }
680 virtual bool is_array_klass_slow() const { return false; }
681 virtual bool is_objArray_klass_slow() const { return false; }
682 virtual bool is_typeArray_klass_slow() const { return false; }
683 #endif // ASSERT
684 public:
685
686 // Fast non-virtual versions
687 #ifndef ASSERT
688 #define assert_same_query(xval, xcheck) xval
689 #else
690 private:
691 static bool assert_same_query(bool xval, bool xslow) {
692 assert(xval == xslow, "slow and fast queries agree");
693 return xval;
694 }
695 public:
696 #endif
697
698 bool is_instance_klass() const { return assert_same_query(_kind <= InstanceStackChunkKlassKind, is_instance_klass_slow()); }
699 // Other is anything that is not one of the more specialized kinds of InstanceKlass.
700 bool is_other_instance_klass() const { return _kind == InstanceKlassKind; }
701 bool is_reference_instance_klass() const { return _kind == InstanceRefKlassKind; }
702 bool is_mirror_instance_klass() const { return _kind == InstanceMirrorKlassKind; }
703 bool is_class_loader_instance_klass() const { return _kind == InstanceClassLoaderKlassKind; }
704 bool is_array_klass() const { return assert_same_query( _kind >= TypeArrayKlassKind, is_array_klass_slow()); }
705 bool is_stack_chunk_instance_klass() const { return _kind == InstanceStackChunkKlassKind; }
706 bool is_objArray_klass() const { return assert_same_query( _kind == ObjArrayKlassKind, is_objArray_klass_slow()); }
707 bool is_typeArray_klass() const { return assert_same_query( _kind == TypeArrayKlassKind, is_typeArray_klass_slow()); }
708 #undef assert_same_query
709
710 // Access flags
711 AccessFlags access_flags() const { return _access_flags; }
712 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
713
714 bool is_public() const { return _access_flags.is_public(); }
715 bool is_final() const { return _access_flags.is_final(); }
716 bool is_interface() const { return _access_flags.is_interface(); }
717 bool is_abstract() const { return _access_flags.is_abstract(); }
718 bool is_super() const { return _access_flags.is_super(); }
719 bool is_synthetic() const { return _access_flags.is_synthetic(); }
720 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
721 bool has_finalizer() const { return _misc_flags.has_finalizer(); }
722 void set_has_finalizer() { _misc_flags.set_has_finalizer(true); }
723 bool is_hidden() const { return _misc_flags.is_hidden_class(); }
724 void set_is_hidden() { _misc_flags.set_is_hidden_class(true); }
725 bool is_value_based() const { return _misc_flags.is_value_based_class(); }
726 void set_is_value_based() { _misc_flags.set_is_value_based_class(true); }
727
728 klass_flags_t misc_flags() const { return _misc_flags.value(); }
729
730 inline bool is_non_strong_hidden() const;
731
732 bool is_cloneable() const;
733 void set_is_cloneable();
734
735 inline markWord prototype_header() const;
736 inline void set_prototype_header(markWord header);
737 static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); }
738
739 JFR_ONLY(DEFINE_TRACE_ID_METHODS;)
740
741 virtual void metaspace_pointers_do(MetaspaceClosure* iter);
742 virtual MetaspaceObj::Type type() const { return ClassType; }
743
744 inline bool is_loader_alive() const;
745
746 void clean_subklass();
747
748 static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true);
749 static void clean_subklass_tree() {
750 clean_weak_klass_links(/*unloading_occurred*/ true , /* clean_alive_klasses */ false);
751 }
752
753 // Return self, except for abstract classes with exactly 1
754 // implementor. Then return the 1 concrete implementation.
755 Klass *up_cast_abstract();
756
757 // klass name
758 Symbol* name() const { return _name; }
759 void set_name(Symbol* n);
760
761 virtual void release_C_heap_structures(bool release_constant_pool = true);
762
763 public:
764 virtual jint compute_modifier_flags() const = 0;
765
766 // JVMTI support
767 virtual jint jvmti_class_status() const;
768
769 // Printing
770 virtual void print_on(outputStream* st) const;
771
772 virtual void oop_print_value_on(oop obj, outputStream* st);
773 virtual void oop_print_on (oop obj, outputStream* st);
774
775 void print_secondary_supers_on(outputStream* st) const;
776
777 virtual const char* internal_name() const = 0;
778
779 // Verification
780 virtual void verify_on(outputStream* st);
781 void verify() { verify_on(tty); }
782
783 #ifndef PRODUCT
784 bool verify_vtable_index(int index);
785 #endif
786
787 virtual void oop_verify_on(oop obj, outputStream* st);
788
789 // for error reporting
790 static bool is_valid(Klass* k);
791
792 static void on_secondary_supers_verification_failure(Klass* super, Klass* sub, bool linear_result, bool table_result, const char* msg);
793
794 // Returns true if this Klass needs to be addressable via narrow Klass ID.
795 inline bool needs_narrow_id() const;
796
797 };
798
799 #endif // SHARE_OOPS_KLASS_HPP