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.
 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 //
 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     InstanceRefKlassKind,
 74     InstanceMirrorKlassKind,
 75     InstanceClassLoaderKlassKind,
 76     InstanceStackChunkKlassKind,
 77     TypeArrayKlassKind,
 78     ObjArrayKlassKind,
 79     UnknownKlassKind
 80   };
 81 
 82   static const uint KLASS_KIND_COUNT = ObjArrayKlassKind + 1;
 83  protected:
 84 
 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
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 private:
171   // This is an index into FileMapHeader::_shared_path_table[], to
172   // associate this class with the JAR file where it's loaded from during
173   // dump time. If a class is not loaded from the shared archive, this field is
174   // -1.
175   s2 _shared_class_path_index;
176 
177 #if INCLUDE_CDS
178   // Various attributes for shared classes. Should be zero for a non-shared class.
179   u2     _shared_class_flags;
180   enum CDSSharedClassFlags {
181     _is_shared_class                       = 1 << 0,  // shadows MetaspaceObj::is_shared
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   Klass(KlassKind kind);
197   Klass();
198 
199   void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw();
200 
201  public:
202   int kind() { return _kind; }
203 
204   enum class DefaultsLookupMode { find, skip };
205   enum class OverpassLookupMode { find, skip };
206   enum class StaticLookupMode   { find, skip };
207   enum class PrivateLookupMode  { find, skip };
208 
209   virtual bool is_klass() const { return true; }
210 
211   // super() cannot be InstanceKlass* -- Java arrays are covariant, and _super is used
212   // to implement that. NB: the _super of "[Ljava/lang/Integer;" is "[Ljava/lang/Number;"
213   // If this is not what your code expects, you're probably looking for Klass::java_super().
214   Klass* super() const               { return _super; }
215   void set_super(Klass* k)           { _super = k; }
216 
217   // initializes _super link, _primary_supers & _secondary_supers arrays
218   void initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS);
219 
220   // klass-specific helper for initializing _secondary_supers
221   virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots,
222                                                           Array<InstanceKlass*>* transitive_interfaces);
223 
224   // java_super is the Java-level super type as specified by Class.getSuperClass.
225   virtual InstanceKlass* java_super() const  { return nullptr; }
226 
227   juint    super_check_offset() const  { return _super_check_offset; }
228   void set_super_check_offset(juint o) { _super_check_offset = o; }
229 
230   Klass* secondary_super_cache() const     { return _secondary_super_cache; }
231   void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; }
232 
233   Array<Klass*>* secondary_supers() const { return _secondary_supers; }
234   void set_secondary_supers(Array<Klass*>* k) { _secondary_supers = k; }
235 
236   // Return the element of the _super chain of the given depth.
237   // If there is no such element, return either null or this.
238   Klass* primary_super_of_depth(juint i) const {
239     assert(i < primary_super_limit(), "oob");
240     Klass* super = _primary_supers[i];
241     assert(super == nullptr || super->super_depth() == i, "correct display");
242     return super;
243   }
244 
245   // Can this klass be a primary super?  False for interfaces and arrays of
246   // interfaces.  False also for arrays or classes with long super chains.
247   bool can_be_primary_super() const {
248     const juint secondary_offset = in_bytes(secondary_super_cache_offset());
249     return super_check_offset() != secondary_offset;
250   }
251   virtual bool can_be_primary_super_slow() const;
252 
253   // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit].
254   juint super_depth() const {
255     if (!can_be_primary_super()) {
256       return primary_super_limit();
257     } else {
258       juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*);
259       assert(d < primary_super_limit(), "oob");
260       assert(_primary_supers[d] == this, "proper init");
261       return d;
262     }
263   }
264 
265   // java mirror
266   oop java_mirror() const;
267   oop java_mirror_no_keepalive() const;
268   void set_java_mirror(Handle m);
269 
270   oop archived_java_mirror() NOT_CDS_JAVA_HEAP_RETURN_(nullptr);
271   void set_archived_java_mirror(int mirror_index) NOT_CDS_JAVA_HEAP_RETURN;
272 
273   // Temporary mirror switch used by RedefineClasses
274   OopHandle java_mirror_handle() const { return _java_mirror; }
275   void swap_java_mirror_handle(OopHandle& mirror) { _java_mirror.swap(mirror); }
276 
277   // Set java mirror OopHandle to null for CDS
278   // This leaves the OopHandle in the CLD, but that's ok, you can't release them.
279   void clear_java_mirror_handle() { _java_mirror = OopHandle(); }
280 
281   // modifier flags
282   jint modifier_flags() const          { return _modifier_flags; }
283   void set_modifier_flags(jint flags)  { _modifier_flags = flags; }
284 
285   // size helper
286   int layout_helper() const            { return _layout_helper; }
287   void set_layout_helper(int lh)       { _layout_helper = lh; }
288 
289   // Note: for instances layout_helper() may include padding.
290   // Use InstanceKlass::contains_field_offset to classify field offsets.
291 
292   // sub/superklass links
293   Klass* subklass(bool log = false) const;
294   Klass* next_sibling(bool log = false) const;
295 
296   InstanceKlass* superklass() const;
297   void append_to_sibling_list();           // add newly created receiver to superklass' subklass list
298 
299   void set_next_link(Klass* k) { _next_link = k; }
300   Klass* next_link() const { return _next_link; }   // The next klass defined by the class loader.
301   Klass** next_link_addr() { return &_next_link; }
302 
303   // class loader data
304   ClassLoaderData* class_loader_data() const               { return _class_loader_data; }
305   void set_class_loader_data(ClassLoaderData* loader_data) {  _class_loader_data = loader_data; }
306 
307   s2 shared_classpath_index() const   {
308     return _shared_class_path_index;
309   };
310 
311   void set_shared_classpath_index(s2 index) {
312     _shared_class_path_index = index;
313   };
314 
315   bool has_archived_mirror_index() const {
316     CDS_JAVA_HEAP_ONLY(return _archived_mirror_index >= 0;)
317     NOT_CDS_JAVA_HEAP(return false);
318   }
319 
320   void clear_archived_mirror_index() NOT_CDS_JAVA_HEAP_RETURN;
321 
322   void set_lambda_proxy_is_available() {
323     CDS_ONLY(_shared_class_flags |= _archived_lambda_proxy_is_available;)
324   }
325   void clear_lambda_proxy_is_available() {
326     CDS_ONLY(_shared_class_flags &= (u2)(~_archived_lambda_proxy_is_available);)
327   }
328   bool lambda_proxy_is_available() const {
329     CDS_ONLY(return (_shared_class_flags & _archived_lambda_proxy_is_available) != 0;)
330     NOT_CDS(return false;)
331   }
332 
333   void set_has_value_based_class_annotation() {
334     CDS_ONLY(_shared_class_flags |= _has_value_based_class_annotation;)
335   }
336   void clear_has_value_based_class_annotation() {
337     CDS_ONLY(_shared_class_flags &= (u2)(~_has_value_based_class_annotation);)
338   }
339   bool has_value_based_class_annotation() const {
340     CDS_ONLY(return (_shared_class_flags & _has_value_based_class_annotation) != 0;)
341     NOT_CDS(return false;)
342   }
343 
344   void set_verified_at_dump_time() {
345     CDS_ONLY(_shared_class_flags |= _verified_at_dump_time;)
346   }
347   bool verified_at_dump_time() const {
348     CDS_ONLY(return (_shared_class_flags & _verified_at_dump_time) != 0;)
349     NOT_CDS(return false;)
350   }
351 
352   void set_has_archived_enum_objs() {
353     CDS_ONLY(_shared_class_flags |= _has_archived_enum_objs;)
354   }
355   bool has_archived_enum_objs() const {
356     CDS_ONLY(return (_shared_class_flags & _has_archived_enum_objs) != 0;)
357     NOT_CDS(return false;)
358   }
359 
360   void set_is_generated_shared_class() {
361     CDS_ONLY(_shared_class_flags |= _is_generated_shared_class;)
362   }
363   bool is_generated_shared_class() const {
364     CDS_ONLY(return (_shared_class_flags & _is_generated_shared_class) != 0;)
365     NOT_CDS(return false;)
366   }
367 








368   bool is_shared() const                { // shadows MetaspaceObj::is_shared)()
369     CDS_ONLY(return (_shared_class_flags & _is_shared_class) != 0;)
370     NOT_CDS(return false;)
371   }
372 
373   void set_is_shared() {
374     CDS_ONLY(_shared_class_flags |= _is_shared_class;)
375   }
376 
377   // Obtain the module or package for this class
378   virtual ModuleEntry* module() const = 0;
379   virtual PackageEntry* package() const = 0;
380 
381  protected:                                // internal accessors
382   void     set_subklass(Klass* s);
383   void     set_next_sibling(Klass* s);
384 
385  public:
386 
387   // Compiler support
388   static ByteSize super_offset()                 { return byte_offset_of(Klass, _super); }
389   static ByteSize super_check_offset_offset()    { return byte_offset_of(Klass, _super_check_offset); }
390   static ByteSize primary_supers_offset()        { return byte_offset_of(Klass, _primary_supers); }
391   static ByteSize secondary_super_cache_offset() { return byte_offset_of(Klass, _secondary_super_cache); }
392   static ByteSize secondary_supers_offset()      { return byte_offset_of(Klass, _secondary_supers); }
393   static ByteSize java_mirror_offset()           { return byte_offset_of(Klass, _java_mirror); }
394   static ByteSize class_loader_data_offset()     { return byte_offset_of(Klass, _class_loader_data); }
395   static ByteSize modifier_flags_offset()        { return byte_offset_of(Klass, _modifier_flags); }
396   static ByteSize layout_helper_offset()         { return byte_offset_of(Klass, _layout_helper); }
397   static ByteSize access_flags_offset()          { return byte_offset_of(Klass, _access_flags); }
398 #if INCLUDE_JVMCI
399   static ByteSize subklass_offset()              { return byte_offset_of(Klass, _subklass); }
400   static ByteSize next_sibling_offset()          { return byte_offset_of(Klass, _next_sibling); }
401 #endif
402 
403   // Unpacking layout_helper:
404   static const int _lh_neutral_value           = 0;  // neutral non-array non-instance value
405   static const int _lh_instance_slow_path_bit  = 0x01;
406   static const int _lh_log2_element_size_shift = BitsPerByte*0;
407   static const int _lh_log2_element_size_mask  = BitsPerLong-1;
408   static const int _lh_element_type_shift      = BitsPerByte*1;
409   static const int _lh_element_type_mask       = right_n_bits(BitsPerByte);  // shifted mask
410   static const int _lh_header_size_shift       = BitsPerByte*2;
411   static const int _lh_header_size_mask        = right_n_bits(BitsPerByte);  // shifted mask
412   static const int _lh_array_tag_bits          = 2;
413   static const int _lh_array_tag_shift         = BitsPerInt - _lh_array_tag_bits;
414   static const int _lh_array_tag_obj_value     = ~0x01;   // 0x80000000 >> 30
415 
416   static const unsigned int _lh_array_tag_type_value = 0Xffffffff; // ~0x00,  // 0xC0000000 >> 30
417 
418   static int layout_helper_size_in_bytes(jint lh) {
419     assert(lh > (jint)_lh_neutral_value, "must be instance");
420     return (int) lh & ~_lh_instance_slow_path_bit;
421   }
422   static bool layout_helper_needs_slow_path(jint lh) {
423     assert(lh > (jint)_lh_neutral_value, "must be instance");
424     return (lh & _lh_instance_slow_path_bit) != 0;
425   }
426   static bool layout_helper_is_instance(jint lh) {
427     return (jint)lh > (jint)_lh_neutral_value;
428   }
429   static bool layout_helper_is_array(jint lh) {
430     return (jint)lh < (jint)_lh_neutral_value;
431   }
432   static bool layout_helper_is_typeArray(jint lh) {
433     // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
434     return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
435   }
436   static bool layout_helper_is_objArray(jint lh) {
437     // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
438     return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
439   }
440   static int layout_helper_header_size(jint lh) {
441     assert(lh < (jint)_lh_neutral_value, "must be array");
442     int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
443     assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
444     return hsize;
445   }
446   static BasicType layout_helper_element_type(jint lh) {
447     assert(lh < (jint)_lh_neutral_value, "must be array");
448     int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
449     assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
450     return (BasicType) btvalue;
451   }
452 
453   // Want a pattern to quickly diff against layout header in register
454   // find something less clever!
455   static int layout_helper_boolean_diffbit() {
456     jint zlh = array_layout_helper(T_BOOLEAN);
457     jint blh = array_layout_helper(T_BYTE);
458     assert(zlh != blh, "array layout helpers must differ");
459     int diffbit = 1;
460     while ((diffbit & (zlh ^ blh)) == 0 && (diffbit & zlh) == 0) {
461       diffbit <<= 1;
462       assert(diffbit != 0, "make sure T_BOOLEAN has a different bit than T_BYTE");
463     }
464     return diffbit;
465   }
466 
467   static int layout_helper_log2_element_size(jint lh) {
468     assert(lh < (jint)_lh_neutral_value, "must be array");
469     int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
470     assert(l2esz <= LogBytesPerLong,
471            "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh);
472     return l2esz;
473   }
474   static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
475     return (tag        << _lh_array_tag_shift)
476       |    (hsize      << _lh_header_size_shift)
477       |    ((int)etype << _lh_element_type_shift)
478       |    (log2_esize << _lh_log2_element_size_shift);
479   }
480   static jint instance_layout_helper(jint size, bool slow_path_flag) {
481     return (size << LogBytesPerWord)
482       |    (slow_path_flag ? _lh_instance_slow_path_bit : 0);
483   }
484   static int layout_helper_to_size_helper(jint lh) {
485     assert(lh > (jint)_lh_neutral_value, "must be instance");
486     // Note that the following expression discards _lh_instance_slow_path_bit.
487     return lh >> LogBytesPerWord;
488   }
489   // Out-of-line version computes everything based on the etype:
490   static jint array_layout_helper(BasicType etype);
491 
492   // What is the maximum number of primary superclasses any klass can have?
493   static juint primary_super_limit()         { return _primary_super_limit; }
494 
495   // vtables
496   klassVtable vtable() const;
497   int vtable_length() const { return _vtable_len; }
498 
499   // subclass check
500   bool is_subclass_of(const Klass* k) const;
501   // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
502   bool is_subtype_of(Klass* k) const {
503     juint    off = k->super_check_offset();
504     Klass* sup = *(Klass**)( (address)this + off );
505     const juint secondary_offset = in_bytes(secondary_super_cache_offset());
506     if (sup == k) {
507       return true;
508     } else if (off != secondary_offset) {
509       return false;
510     } else {
511       return search_secondary_supers(k);
512     }
513   }
514 
515   bool search_secondary_supers(Klass* k) const;
516 
517   // Find LCA in class hierarchy
518   Klass *LCA( Klass *k );
519 
520   // Check whether reflection/jni/jvm code is allowed to instantiate this class;
521   // if not, throw either an Error or an Exception.
522   virtual void check_valid_for_instantiation(bool throwError, TRAPS);
523 
524   // array copying
525   virtual void  copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
526 
527   // tells if the class should be initialized
528   virtual bool should_be_initialized() const    { return false; }
529   // initializes the klass
530   virtual void initialize(TRAPS);
531   virtual Klass* find_field(Symbol* name, Symbol* signature, fieldDescriptor* fd) const;
532   virtual Method* uncached_lookup_method(const Symbol* name, const Symbol* signature,
533                                          OverpassLookupMode overpass_mode,
534                                          PrivateLookupMode = PrivateLookupMode::find) const;
535  public:
536   Method* lookup_method(const Symbol* name, const Symbol* signature) const {
537     return uncached_lookup_method(name, signature, OverpassLookupMode::find);
538   }
539 
540   // array class with specific rank
541   virtual ArrayKlass* array_klass(int rank, TRAPS) = 0;
542 
543   // array class with this klass as element type
544   virtual ArrayKlass* array_klass(TRAPS) = 0;
545 
546   // These will return null instead of allocating on the heap:
547   virtual ArrayKlass* array_klass_or_null(int rank) = 0;
548   virtual ArrayKlass* array_klass_or_null() = 0;
549 
550   virtual oop protection_domain() const = 0;
551 
552   oop class_loader() const;

553 
554   inline oop klass_holder() const;
555 
556  protected:
557 
558   // Error handling when length > max_length or length < 0
559   static void check_array_allocation_length(int length, int max_length, TRAPS);
560 
561   void set_vtable_length(int len) { _vtable_len= len; }
562 
563   vtableEntry* start_of_vtable() const;
564 #if INCLUDE_CDS
565   void restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS);
566 #endif
567  public:
568   Method* method_at_vtable(int index);
569 
570   static ByteSize vtable_start_offset();
571   static ByteSize vtable_length_offset() {
572     return byte_offset_of(Klass, _vtable_len);
573   }
574 
575 #if INCLUDE_CDS
576   // CDS support - remove and restore oops from metadata. Oops are not shared.
577   virtual void remove_unshareable_info();
578   virtual void remove_java_mirror();
579 
580   bool is_unshareable_info_restored() const {
581     assert(is_shared(), "use this for shared classes only");
582     if (has_archived_mirror_index()) {
583       // _java_mirror is not a valid OopHandle but rather an encoded reference in the shared heap
584       return false;
585     } else if (_java_mirror.is_empty()) {
586       return false;
587     } else {
588       return true;
589     }
590   }
591 #endif // INCLUDE_CDS
592 
593  public:
594   // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
595   // These functions describe behavior for the oop not the KLASS.
596 
597   // actual oop size of obj in memory in word size.
598   virtual size_t oop_size(oop obj) const = 0;
599 
600   // Size of klass in word size.
601   virtual int size() const = 0;
602 
603   // Returns the Java name for a class (Resource allocated)
604   // For arrays, this returns the name of the element with a leading '['.
605   // For classes, this returns the name with the package separators
606   //     turned into '.'s.
607   const char* external_name() const;
608   // Returns the name for a class (Resource allocated) as the class
609   // would appear in a signature.
610   // For arrays, this returns the name of the element with a leading '['.
611   // For classes, this returns the name with a leading 'L' and a trailing ';'
612   //     and the package separators as '/'.
613   virtual const char* signature_name() const;
614 
615   const char* joint_in_module_of_loader(const Klass* class2, bool include_parent_loader = false) const;
616   const char* class_in_module_of_loader(bool use_are = false, bool include_parent_loader = false) const;
617 
618   // Returns "interface", "abstract class" or "class".
619   const char* external_kind() const;
620 
621   // type testing operations
622 #ifdef ASSERT
623  protected:
624   virtual bool is_instance_klass_slow()     const { return false; }
625   virtual bool is_array_klass_slow()        const { return false; }
626   virtual bool is_objArray_klass_slow()     const { return false; }
627   virtual bool is_typeArray_klass_slow()    const { return false; }
628 #endif // ASSERT
629  public:
630 
631   // Fast non-virtual versions
632   #ifndef ASSERT
633   #define assert_same_query(xval, xcheck) xval
634   #else
635  private:
636   static bool assert_same_query(bool xval, bool xslow) {
637     assert(xval == xslow, "slow and fast queries agree");
638     return xval;
639   }
640  public:
641   #endif
642 
643   bool is_instance_klass()              const { return assert_same_query(_kind <= InstanceStackChunkKlassKind, is_instance_klass_slow()); }
644   // Other is anything that is not one of the more specialized kinds of InstanceKlass.
645   bool is_other_instance_klass()        const { return _kind == InstanceKlassKind; }
646   bool is_reference_instance_klass()    const { return _kind == InstanceRefKlassKind; }
647   bool is_mirror_instance_klass()       const { return _kind == InstanceMirrorKlassKind; }
648   bool is_class_loader_instance_klass() const { return _kind == InstanceClassLoaderKlassKind; }
649   bool is_array_klass()                 const { return assert_same_query( _kind >= TypeArrayKlassKind, is_array_klass_slow()); }
650   bool is_stack_chunk_instance_klass()  const { return _kind == InstanceStackChunkKlassKind; }
651   bool is_objArray_klass()              const { return assert_same_query( _kind == ObjArrayKlassKind,  is_objArray_klass_slow()); }
652   bool is_typeArray_klass()             const { return assert_same_query( _kind == TypeArrayKlassKind, is_typeArray_klass_slow()); }
653   #undef assert_same_query
654 
655   // Access flags
656   AccessFlags access_flags() const         { return _access_flags;  }
657   void set_access_flags(AccessFlags flags) { _access_flags = flags; }
658 
659   bool is_public() const                { return _access_flags.is_public(); }
660   bool is_final() const                 { return _access_flags.is_final(); }
661   bool is_interface() const             { return _access_flags.is_interface(); }
662   bool is_abstract() const              { return _access_flags.is_abstract(); }
663   bool is_super() const                 { return _access_flags.is_super(); }
664   bool is_synthetic() const             { return _access_flags.is_synthetic(); }
665   void set_is_synthetic()               { _access_flags.set_is_synthetic(); }
666   bool has_finalizer() const            { return _access_flags.has_finalizer(); }
667   void set_has_finalizer()              { _access_flags.set_has_finalizer(); }
668   bool is_hidden() const                { return access_flags().is_hidden_class(); }
669   void set_is_hidden()                  { _access_flags.set_is_hidden_class(); }
670   bool is_value_based()                 { return _access_flags.is_value_based_class(); }
671   void set_is_value_based()             { _access_flags.set_is_value_based_class(); }
672 
673   inline bool is_non_strong_hidden() const;
674 
675   bool is_cloneable() const;
676   void set_is_cloneable();
677 
678   JFR_ONLY(DEFINE_TRACE_ID_METHODS;)
679 
680   virtual void metaspace_pointers_do(MetaspaceClosure* iter);
681   virtual MetaspaceObj::Type type() const { return ClassType; }
682 
683   inline bool is_loader_alive() const;
684 
685   void clean_subklass();
686 
687   static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true);
688   static void clean_subklass_tree() {
689     clean_weak_klass_links(/*unloading_occurred*/ true , /* clean_alive_klasses */ false);
690   }
691 
692   // Return self, except for abstract classes with exactly 1
693   // implementor.  Then return the 1 concrete implementation.
694   Klass *up_cast_abstract();
695 
696   // klass name
697   Symbol* name() const                   { return _name; }
698   void set_name(Symbol* n);
699 
700   virtual void release_C_heap_structures(bool release_constant_pool = true);
701 
702  public:
703   virtual jint compute_modifier_flags() const = 0;
704 
705   // JVMTI support
706   virtual jint jvmti_class_status() const;
707 
708   // Printing
709   virtual void print_on(outputStream* st) const;
710 
711   virtual void oop_print_value_on(oop obj, outputStream* st);
712   virtual void oop_print_on      (oop obj, outputStream* st);
713 
714   virtual const char* internal_name() const = 0;
715 
716   // Verification
717   virtual void verify_on(outputStream* st);
718   void verify() { verify_on(tty); }
719 
720 #ifndef PRODUCT
721   bool verify_vtable_index(int index);
722 #endif
723 
724   virtual void oop_verify_on(oop obj, outputStream* st);
725 
726   // for error reporting
727   static bool is_valid(Klass* k);
728 };
729 
730 #endif // SHARE_OOPS_KLASS_HPP
--- EOF ---