49 // a vtbl and does the C++ dispatch depending on the object's
50 // actual type. (See oop.inline.hpp for some of the forwarding code.)
51 // ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"!
52
53 // Forward declarations.
54 template <class T> class Array;
55 template <class T> class GrowableArray;
56 class ClassLoaderData;
57 class fieldDescriptor;
58 class klassVtable;
59 class ModuleEntry;
60 class PackageEntry;
61 class vtableEntry;
62
63 class Klass : public Metadata {
64
65 friend class VMStructs;
66 friend class JVMCIVMStructs;
67 public:
68 // Klass Kinds for all subclasses of Klass
69 enum KlassKind : u2 {
70 InstanceKlassKind,
71 InstanceRefKlassKind,
72 InstanceMirrorKlassKind,
73 InstanceClassLoaderKlassKind,
74 InstanceStackChunkKlassKind,
75 TypeArrayKlassKind,
76 ObjArrayKlassKind,
77 UnknownKlassKind
78 };
79
80 static const uint KLASS_KIND_COUNT = ObjArrayKlassKind + 1;
81 protected:
82
83 // If you add a new field that points to any metaspace object, you
84 // must add this field to Klass::metaspace_pointers_do().
85
86 // note: put frequently-used fields together at start of klass structure
87 // for better cache behavior (may not make much of a difference but sure won't hurt)
88 enum { _primary_super_limit = 8 };
89
90 // The "layout helper" is a combined descriptor of object layout.
91 // For klasses which are neither instance nor array, the value is zero.
92 //
93 // For instances, layout helper is a positive number, the instance size.
94 // This size is already passed through align_object_size and scaled to bytes.
95 // The low order bit is set if instances of this class cannot be
96 // allocated using the fastpath.
97 //
98 // For arrays, layout helper is a negative number, containing four
99 // distinct bytes, as follows:
100 // MSB:[tag, hsz, ebt, log2(esz)]:LSB
101 // where:
102 // tag is 0x80 if the elements are oops, 0xC0 if non-oops
103 // hsz is array header size in bytes (i.e., offset of first element)
104 // ebt is the BasicType of the elements
105 // esz is the element size in bytes
106 // This packed word is arranged so as to be quickly unpacked by the
107 // various fast paths that use the various subfields.
108 //
109 // The esz bits can be used directly by a SLL instruction, without masking.
110 //
111 // Note that the array-kind tag looks like 0x00 for instance klasses,
112 // since their length in bytes is always less than 24Mb.
113 //
114 // Final note: This comes first, immediately after C++ vtable,
115 // because it is frequently queried.
116 jint _layout_helper;
117
118 // Klass kind used to resolve the runtime type of the instance.
119 // - Used to implement devirtualized oop closure dispatching.
120 // - Various type checking in the JVM
121 const KlassKind _kind;
122
185 // or classpath.
186 _is_generated_shared_class = 1 << 5,
187 // archived mirror already initialized by AOT-cache assembly: no further need to call <clinit>
188 _has_aot_initialized_mirror = 1 << 6,
189 };
190 #endif
191
192 int _vtable_len; // vtable length. This field may be read very often when we
193 // have lots of itable dispatches (e.g., lambdas and streams).
194 // Keep it away from the beginning of a Klass to avoid cacheline
195 // contention that may happen when a nearby object is modified.
196
197 CDS_JAVA_HEAP_ONLY(int _archived_mirror_index;)
198
199 public:
200
201 JFR_ONLY(DEFINE_TRACE_ID_FIELD;)
202
203 protected:
204
205 Klass(KlassKind kind);
206 Klass();
207
208 public:
209 int kind() { return _kind; }
210
211 enum class DefaultsLookupMode { find, skip };
212 enum class OverpassLookupMode { find, skip };
213 enum class StaticLookupMode { find, skip };
214 enum class PrivateLookupMode { find, skip };
215
216 virtual bool is_klass() const { return true; }
217
218 // super() cannot be InstanceKlass* -- Java arrays are covariant, and _super is used
219 // to implement that. NB: the _super of "[Ljava/lang/Integer;" is "[Ljava/lang/Number;"
220 // If this is not what your code expects, you're probably looking for:
221 // - Klass::java_super() - if you have a Klass*
222 // - InstanceKlass::super() - if you have an InstanceKlass* ik, ik->super() returns InstanceKlass*.
223 Klass* super() const { return _super; }
224 void set_super(Klass* k) { _super = k; }
225
433 static ByteSize layout_helper_offset() { return byte_offset_of(Klass, _layout_helper); }
434 static ByteSize access_flags_offset() { return byte_offset_of(Klass, _access_flags); }
435 #if INCLUDE_JVMCI
436 static ByteSize subklass_offset() { return byte_offset_of(Klass, _subklass); }
437 static ByteSize next_sibling_offset() { return byte_offset_of(Klass, _next_sibling); }
438 #endif
439 static ByteSize secondary_supers_bitmap_offset()
440 { return byte_offset_of(Klass, _secondary_supers_bitmap); }
441 static ByteSize hash_slot_offset() { return byte_offset_of(Klass, _hash_slot); }
442 static ByteSize misc_flags_offset() { return byte_offset_of(Klass, _misc_flags._flags); }
443
444 // Unpacking layout_helper:
445 static const int _lh_neutral_value = 0; // neutral non-array non-instance value
446 static const int _lh_instance_slow_path_bit = 0x01;
447 static const int _lh_log2_element_size_shift = BitsPerByte*0;
448 static const int _lh_log2_element_size_mask = BitsPerLong-1;
449 static const int _lh_element_type_shift = BitsPerByte*1;
450 static const int _lh_element_type_mask = right_n_bits(BitsPerByte); // shifted mask
451 static const int _lh_header_size_shift = BitsPerByte*2;
452 static const int _lh_header_size_mask = right_n_bits(BitsPerByte); // shifted mask
453 static const int _lh_array_tag_bits = 2;
454 static const int _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits;
455 static const int _lh_array_tag_obj_value = ~0x01; // 0x80000000 >> 30
456
457 static const unsigned int _lh_array_tag_type_value = 0Xffffffff; // ~0x00, // 0xC0000000 >> 30
458
459 static int layout_helper_size_in_bytes(jint lh) {
460 assert(lh > (jint)_lh_neutral_value, "must be instance");
461 return (int) lh & ~_lh_instance_slow_path_bit;
462 }
463 static bool layout_helper_needs_slow_path(jint lh) {
464 assert(lh > (jint)_lh_neutral_value, "must be instance");
465 return (lh & _lh_instance_slow_path_bit) != 0;
466 }
467 static bool layout_helper_is_instance(jint lh) {
468 return (jint)lh > (jint)_lh_neutral_value;
469 }
470 static bool layout_helper_is_array(jint lh) {
471 return (jint)lh < (jint)_lh_neutral_value;
472 }
473 static bool layout_helper_is_typeArray(jint lh) {
474 // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
475 return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
476 }
477 static bool layout_helper_is_objArray(jint lh) {
478 // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
479 return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
480 }
481 static int layout_helper_header_size(jint lh) {
482 assert(lh < (jint)_lh_neutral_value, "must be array");
483 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
484 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
485 return hsize;
486 }
487 static BasicType layout_helper_element_type(jint lh) {
488 assert(lh < (jint)_lh_neutral_value, "must be array");
489 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
490 assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
491 return (BasicType) btvalue;
492 }
493
494 // Want a pattern to quickly diff against layout header in register
495 // find something less clever!
496 static int layout_helper_boolean_diffbit() {
497 jint zlh = array_layout_helper(T_BOOLEAN);
498 jint blh = array_layout_helper(T_BYTE);
499 assert(zlh != blh, "array layout helpers must differ");
500 int diffbit = 1;
501 while ((diffbit & (zlh ^ blh)) == 0 && (diffbit & zlh) == 0) {
502 diffbit <<= 1;
503 assert(diffbit != 0, "make sure T_BOOLEAN has a different bit than T_BYTE");
504 }
505 return diffbit;
506 }
507
508 static int layout_helper_log2_element_size(jint lh) {
509 assert(lh < (jint)_lh_neutral_value, "must be array");
510 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
511 assert(l2esz <= LogBytesPerLong,
512 "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh);
513 return l2esz;
514 }
515 static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
516 return (tag << _lh_array_tag_shift)
517 | (hsize << _lh_header_size_shift)
518 | ((int)etype << _lh_element_type_shift)
519 | (log2_esize << _lh_log2_element_size_shift);
520 }
521 static jint instance_layout_helper(jint size, bool slow_path_flag) {
522 return (size << LogBytesPerWord)
523 | (slow_path_flag ? _lh_instance_slow_path_bit : 0);
524 }
525 static int layout_helper_to_size_helper(jint lh) {
526 assert(lh > (jint)_lh_neutral_value, "must be instance");
527 // Note that the following expression discards _lh_instance_slow_path_bit.
528 return lh >> LogBytesPerWord;
529 }
530 // Out-of-line version computes everything based on the etype:
531 static jint array_layout_helper(BasicType etype);
532
533 // What is the maximum number of primary superclasses any klass can have?
534 static juint primary_super_limit() { return _primary_super_limit; }
535
536 // vtables
639 const char* external_name() const;
640 // Returns the name for a class (Resource allocated) as the class
641 // would appear in a signature.
642 // For arrays, this returns the name of the element with a leading '['.
643 // For classes, this returns the name with a leading 'L' and a trailing ';'
644 // and the package separators as '/'.
645 virtual const char* signature_name() const;
646
647 const char* joint_in_module_of_loader(const Klass* class2, bool include_parent_loader = false) const;
648 const char* class_in_module_of_loader(bool use_are = false, bool include_parent_loader = false) const;
649
650 // Returns "interface", "abstract class" or "class".
651 const char* external_kind() const;
652
653 // type testing operations
654 #ifdef ASSERT
655 protected:
656 virtual bool is_instance_klass_slow() const { return false; }
657 virtual bool is_array_klass_slow() const { return false; }
658 virtual bool is_objArray_klass_slow() const { return false; }
659 virtual bool is_typeArray_klass_slow() const { return false; }
660 #endif // ASSERT
661 public:
662
663 // Fast non-virtual versions
664 #ifndef ASSERT
665 #define assert_same_query(xval, xcheck) xval
666 #else
667 private:
668 static bool assert_same_query(bool xval, bool xslow) {
669 assert(xval == xslow, "slow and fast queries agree");
670 return xval;
671 }
672 public:
673 #endif
674
675 bool is_instance_klass() const { return assert_same_query(_kind <= InstanceStackChunkKlassKind, is_instance_klass_slow()); }
676 // Other is anything that is not one of the more specialized kinds of InstanceKlass.
677 bool is_other_instance_klass() const { return _kind == InstanceKlassKind; }
678 bool is_reference_instance_klass() const { return _kind == InstanceRefKlassKind; }
679 bool is_mirror_instance_klass() const { return _kind == InstanceMirrorKlassKind; }
680 bool is_class_loader_instance_klass() const { return _kind == InstanceClassLoaderKlassKind; }
681 bool is_array_klass() const { return assert_same_query( _kind >= TypeArrayKlassKind, is_array_klass_slow()); }
682 bool is_stack_chunk_instance_klass() const { return _kind == InstanceStackChunkKlassKind; }
683 bool is_objArray_klass() const { return assert_same_query( _kind == ObjArrayKlassKind, is_objArray_klass_slow()); }
684 bool is_typeArray_klass() const { return assert_same_query( _kind == TypeArrayKlassKind, is_typeArray_klass_slow()); }
685 #undef assert_same_query
686
687 // Access flags
688 AccessFlags access_flags() const { return _access_flags; }
689 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
690
691 bool is_public() const { return _access_flags.is_public(); }
692 bool is_final() const { return _access_flags.is_final(); }
693 bool is_interface() const { return _access_flags.is_interface(); }
694 bool is_abstract() const { return _access_flags.is_abstract(); }
695 bool is_super() const { return _access_flags.is_super(); }
696 bool is_synthetic() const { return _access_flags.is_synthetic(); }
697 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
698 bool has_finalizer() const { return _misc_flags.has_finalizer(); }
699 void set_has_finalizer() { _misc_flags.set_has_finalizer(true); }
700 bool is_hidden() const { return _misc_flags.is_hidden_class(); }
701 void set_is_hidden() { _misc_flags.set_is_hidden_class(true); }
702 bool is_value_based() const { return _misc_flags.is_value_based_class(); }
703 void set_is_value_based() { _misc_flags.set_is_value_based_class(true); }
704
705 klass_flags_t misc_flags() const { return _misc_flags.value(); }
706
707 inline bool is_non_strong_hidden() const;
708
709 bool is_cloneable() const;
710 void set_is_cloneable();
711
712 inline markWord prototype_header() const;
713 inline void set_prototype_header(markWord header);
714 static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); }
715
716 JFR_ONLY(DEFINE_TRACE_ID_METHODS;)
717
718 virtual void metaspace_pointers_do(MetaspaceClosure* iter);
719 virtual MetaspaceObj::Type type() const { return ClassType; }
720
721 inline bool is_loader_alive() const;
722 inline bool is_loader_present_and_alive() const;
723
724 void clean_subklass();
725
726 // Clean out unnecessary weak klass links from the whole klass hierarchy.
727 static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true);
728 // Clean out unnecessary weak klass links from the given InstanceKlass.
729 static void clean_weak_instanceklass_links(InstanceKlass* ik);
730
731 // Return self, except for abstract classes with exactly 1
732 // implementor. Then return the 1 concrete implementation.
733 Klass *up_cast_abstract();
734
|
49 // a vtbl and does the C++ dispatch depending on the object's
50 // actual type. (See oop.inline.hpp for some of the forwarding code.)
51 // ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"!
52
53 // Forward declarations.
54 template <class T> class Array;
55 template <class T> class GrowableArray;
56 class ClassLoaderData;
57 class fieldDescriptor;
58 class klassVtable;
59 class ModuleEntry;
60 class PackageEntry;
61 class vtableEntry;
62
63 class Klass : public Metadata {
64
65 friend class VMStructs;
66 friend class JVMCIVMStructs;
67 public:
68 // Klass Kinds for all subclasses of Klass
69 enum KlassKind : u2
70 {
71 InstanceKlassKind,
72 InlineKlassKind,
73 InstanceRefKlassKind,
74 InstanceMirrorKlassKind,
75 InstanceClassLoaderKlassKind,
76 InstanceStackChunkKlassKind,
77 TypeArrayKlassKind,
78 ObjArrayKlassKind,
79 RefArrayKlassKind,
80 FlatArrayKlassKind,
81 UnknownKlassKind
82 };
83
84 static const uint KLASS_KIND_COUNT = FlatArrayKlassKind + 1;
85 protected:
86
87 // If you add a new field that points to any metaspace object, you
88 // must add this field to Klass::metaspace_pointers_do().
89
90 // note: put frequently-used fields together at start of klass structure
91 // for better cache behavior (may not make much of a difference but sure won't hurt)
92 enum { _primary_super_limit = 8 };
93
94 // The "layout helper" is a combined descriptor of object layout.
95 // For klasses which are neither instance nor array, the value is zero.
96 //
97 // For instances, layout helper is a positive number, the instance size.
98 // This size is already passed through align_object_size and scaled to bytes.
99 // The low order bit is set if instances of this class cannot be
100 // allocated using the fastpath.
101 //
102 // For arrays, layout helper is a negative number, containing four
103 // distinct bytes, as follows:
104 // MSB:[tag, hsz, ebt, log2(esz)]:LSB
105 // where:
106 // tag is 0x80 if the elements are oops, 0xC0 if non-oops, 0xA0 if value types
107 // hsz is array header size in bytes (i.e., offset of first element)
108 // ebt is the BasicType of the elements
109 // esz is the element size in bytes
110 // This packed word is arranged so as to be quickly unpacked by the
111 // various fast paths that use the various subfields.
112 //
113 // The esz bits can be used directly by a SLL instruction, without masking.
114 //
115 // Note that the array-kind tag looks like 0x00 for instance klasses,
116 // since their length in bytes is always less than 24Mb.
117 //
118 // Final note: This comes first, immediately after C++ vtable,
119 // because it is frequently queried.
120 jint _layout_helper;
121
122 // Klass kind used to resolve the runtime type of the instance.
123 // - Used to implement devirtualized oop closure dispatching.
124 // - Various type checking in the JVM
125 const KlassKind _kind;
126
189 // or classpath.
190 _is_generated_shared_class = 1 << 5,
191 // archived mirror already initialized by AOT-cache assembly: no further need to call <clinit>
192 _has_aot_initialized_mirror = 1 << 6,
193 };
194 #endif
195
196 int _vtable_len; // vtable length. This field may be read very often when we
197 // have lots of itable dispatches (e.g., lambdas and streams).
198 // Keep it away from the beginning of a Klass to avoid cacheline
199 // contention that may happen when a nearby object is modified.
200
201 CDS_JAVA_HEAP_ONLY(int _archived_mirror_index;)
202
203 public:
204
205 JFR_ONLY(DEFINE_TRACE_ID_FIELD;)
206
207 protected:
208
209 Klass(KlassKind kind, markWord prototype_header = markWord::prototype());
210 Klass();
211
212 public:
213 int kind() { return _kind; }
214
215 enum class DefaultsLookupMode { find, skip };
216 enum class OverpassLookupMode { find, skip };
217 enum class StaticLookupMode { find, skip };
218 enum class PrivateLookupMode { find, skip };
219
220 virtual bool is_klass() const { return true; }
221
222 // super() cannot be InstanceKlass* -- Java arrays are covariant, and _super is used
223 // to implement that. NB: the _super of "[Ljava/lang/Integer;" is "[Ljava/lang/Number;"
224 // If this is not what your code expects, you're probably looking for:
225 // - Klass::java_super() - if you have a Klass*
226 // - InstanceKlass::super() - if you have an InstanceKlass* ik, ik->super() returns InstanceKlass*.
227 Klass* super() const { return _super; }
228 void set_super(Klass* k) { _super = k; }
229
437 static ByteSize layout_helper_offset() { return byte_offset_of(Klass, _layout_helper); }
438 static ByteSize access_flags_offset() { return byte_offset_of(Klass, _access_flags); }
439 #if INCLUDE_JVMCI
440 static ByteSize subklass_offset() { return byte_offset_of(Klass, _subklass); }
441 static ByteSize next_sibling_offset() { return byte_offset_of(Klass, _next_sibling); }
442 #endif
443 static ByteSize secondary_supers_bitmap_offset()
444 { return byte_offset_of(Klass, _secondary_supers_bitmap); }
445 static ByteSize hash_slot_offset() { return byte_offset_of(Klass, _hash_slot); }
446 static ByteSize misc_flags_offset() { return byte_offset_of(Klass, _misc_flags._flags); }
447
448 // Unpacking layout_helper:
449 static const int _lh_neutral_value = 0; // neutral non-array non-instance value
450 static const int _lh_instance_slow_path_bit = 0x01;
451 static const int _lh_log2_element_size_shift = BitsPerByte*0;
452 static const int _lh_log2_element_size_mask = BitsPerLong-1;
453 static const int _lh_element_type_shift = BitsPerByte*1;
454 static const int _lh_element_type_mask = right_n_bits(BitsPerByte); // shifted mask
455 static const int _lh_header_size_shift = BitsPerByte*2;
456 static const int _lh_header_size_mask = right_n_bits(BitsPerByte); // shifted mask
457 static const int _lh_array_tag_bits = 4;
458 static const int _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits;
459
460 static const unsigned int _lh_array_tag_type_value = 0Xfffffffc;
461 static const unsigned int _lh_array_tag_flat_value = 0Xfffffffa;
462 static const unsigned int _lh_array_tag_ref_value = 0Xfffffff8;
463
464 // null-free array flag bit under the array tag bits, shift one more to get array tag value
465 static const int _lh_null_free_shift = _lh_array_tag_shift - 1;
466 static const int _lh_null_free_mask = 1;
467
468 static const jint _lh_array_tag_flat_value_bit_inplace = (jint) (1 << (_lh_array_tag_shift + 1));
469
470 static int layout_helper_size_in_bytes(jint lh) {
471 assert(lh > (jint)_lh_neutral_value, "must be instance");
472 return (int) lh & ~_lh_instance_slow_path_bit;
473 }
474 static bool layout_helper_needs_slow_path(jint lh) {
475 assert(lh > (jint)_lh_neutral_value, "must be instance");
476 return (lh & _lh_instance_slow_path_bit) != 0;
477 }
478 static bool layout_helper_is_instance(jint lh) {
479 return (jint)lh > (jint)_lh_neutral_value;
480 }
481 static bool layout_helper_is_array(jint lh) {
482 return (jint)lh < (jint)_lh_neutral_value;
483 }
484 static bool layout_helper_is_typeArray(jint lh) {
485 return (juint) _lh_array_tag_type_value == (juint)(lh >> _lh_array_tag_shift);
486 }
487 static bool layout_helper_is_refArray(jint lh) {
488 return (juint)_lh_array_tag_ref_value == (juint)(lh >> _lh_array_tag_shift);
489 }
490 static bool layout_helper_is_flatArray(jint lh) {
491 return (juint)_lh_array_tag_flat_value == (juint)(lh >> _lh_array_tag_shift);
492 }
493 static bool layout_helper_is_null_free(jint lh) {
494 assert(layout_helper_is_flatArray(lh) || layout_helper_is_refArray(lh), "must be array of inline types");
495 return ((lh >> _lh_null_free_shift) & _lh_null_free_mask);
496 }
497 static jint layout_helper_set_null_free(jint lh) {
498 lh |= (_lh_null_free_mask << _lh_null_free_shift);
499 assert(layout_helper_is_null_free(lh), "Bad encoding");
500 return lh;
501 }
502 static int layout_helper_header_size(jint lh) {
503 assert(lh < (jint)_lh_neutral_value, "must be array");
504 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
505 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
506 return hsize;
507 }
508 static BasicType layout_helper_element_type(jint lh) {
509 assert(lh < (jint)_lh_neutral_value, "must be array");
510 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
511 assert((btvalue >= T_BOOLEAN && btvalue <= T_OBJECT) || btvalue == T_FLAT_ELEMENT, "sanity");
512 return (BasicType) btvalue;
513 }
514
515 // Want a pattern to quickly diff against layout header in register
516 // find something less clever!
517 static int layout_helper_boolean_diffbit() {
518 jint zlh = array_layout_helper(T_BOOLEAN);
519 jint blh = array_layout_helper(T_BYTE);
520 assert(zlh != blh, "array layout helpers must differ");
521 int diffbit = 1;
522 while ((diffbit & (zlh ^ blh)) == 0 && (diffbit & zlh) == 0) {
523 diffbit <<= 1;
524 assert(diffbit != 0, "make sure T_BOOLEAN has a different bit than T_BYTE");
525 }
526 return diffbit;
527 }
528
529 static int layout_helper_log2_element_size(jint lh) {
530 assert(lh < (jint)_lh_neutral_value, "must be array");
531 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
532 assert(layout_helper_element_type(lh) == T_FLAT_ELEMENT || l2esz <= LogBytesPerLong,
533 "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh);
534 return l2esz;
535 }
536 static jint array_layout_helper(jint tag, bool null_free, int hsize, BasicType etype, int log2_esize) {
537 return (tag << _lh_array_tag_shift)
538 | ((null_free ? 1 : 0) << _lh_null_free_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
661 const char* external_name() const;
662 // Returns the name for a class (Resource allocated) as the class
663 // would appear in a signature.
664 // For arrays, this returns the name of the element with a leading '['.
665 // For classes, this returns the name with a leading 'L' and a trailing ';'
666 // and the package separators as '/'.
667 virtual const char* signature_name() const;
668
669 const char* joint_in_module_of_loader(const Klass* class2, bool include_parent_loader = false) const;
670 const char* class_in_module_of_loader(bool use_are = false, bool include_parent_loader = false) const;
671
672 // Returns "interface", "abstract class" or "class".
673 const char* external_kind() const;
674
675 // type testing operations
676 #ifdef ASSERT
677 protected:
678 virtual bool is_instance_klass_slow() const { return false; }
679 virtual bool is_array_klass_slow() const { return false; }
680 virtual bool is_objArray_klass_slow() const { return false; }
681 virtual bool is_refArray_klass_slow() const { return false; }
682 virtual bool is_typeArray_klass_slow() const { return false; }
683 virtual bool is_flatArray_klass_slow() const { return false; }
684 #endif // ASSERT
685 // current implementation uses this method even in non debug builds
686 virtual bool is_inline_klass_slow() const { return false; }
687 public:
688
689 // Fast non-virtual versions
690 #ifndef ASSERT
691 #define assert_same_query(xval, xcheck) xval
692 #else
693 private:
694 static bool assert_same_query(bool xval, bool xslow) {
695 assert(xval == xslow, "slow and fast queries agree");
696 return xval;
697 }
698 public:
699 #endif
700
701 bool is_instance_klass() const { return assert_same_query(_kind <= InstanceStackChunkKlassKind, is_instance_klass_slow()); }
702 bool is_inline_klass() const { return assert_same_query(_kind == InlineKlassKind, is_inline_klass_slow()); }
703 bool is_reference_instance_klass() const { return _kind == InstanceRefKlassKind; }
704 bool is_mirror_instance_klass() const { return _kind == InstanceMirrorKlassKind; }
705 bool is_class_loader_instance_klass() const { return _kind == InstanceClassLoaderKlassKind; }
706 bool is_array_klass() const { return assert_same_query( _kind >= TypeArrayKlassKind, is_array_klass_slow()); }
707 bool is_stack_chunk_instance_klass() const { return _kind == InstanceStackChunkKlassKind; }
708 bool is_flatArray_klass() const { return assert_same_query( _kind == FlatArrayKlassKind, is_flatArray_klass_slow()); }
709 bool is_objArray_klass() const { return assert_same_query( _kind == ObjArrayKlassKind || _kind == RefArrayKlassKind || _kind == FlatArrayKlassKind, is_objArray_klass_slow()); }
710 bool is_refArray_klass() const { return assert_same_query( _kind == RefArrayKlassKind, is_refArray_klass_slow()); }
711 bool is_typeArray_klass() const { return assert_same_query( _kind == TypeArrayKlassKind, is_typeArray_klass_slow()); }
712 bool is_refined_objArray_klass() const { return is_refArray_klass() || is_flatArray_klass(); }
713 #undef assert_same_query
714
715 inline bool is_null_free_array_klass() const { return !is_typeArray_klass() && layout_helper_is_null_free(layout_helper()); }
716
717 // Access flags
718 AccessFlags access_flags() const { return _access_flags; }
719 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
720
721 bool is_public() const { return _access_flags.is_public(); }
722 bool is_final() const { return _access_flags.is_final(); }
723 bool is_interface() const { return _access_flags.is_interface(); }
724 bool is_abstract() const { return _access_flags.is_abstract(); }
725 bool is_synthetic() const { return _access_flags.is_synthetic(); }
726 bool is_identity_class() const { assert(is_instance_klass(), "only for instanceKlass"); return _access_flags.is_identity_class(); }
727 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
728 bool has_finalizer() const { return _misc_flags.has_finalizer(); }
729 void set_has_finalizer() { _misc_flags.set_has_finalizer(true); }
730 bool is_hidden() const { return _misc_flags.is_hidden_class(); }
731 void set_is_hidden() { _misc_flags.set_is_hidden_class(true); }
732 bool is_value_based() const { return _misc_flags.is_value_based_class(); }
733 void set_is_value_based() { _misc_flags.set_is_value_based_class(true); }
734
735 klass_flags_t misc_flags() const { return _misc_flags.value(); }
736
737 inline bool is_non_strong_hidden() const;
738
739 bool is_cloneable() const;
740 void set_is_cloneable();
741
742 static inline markWord make_prototype_header(const Klass* kls, markWord prototype = markWord::prototype());
743 inline markWord prototype_header() const;
744 inline void set_prototype_header(markWord header);
745 static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); }
746 inline void set_prototype_header_klass(narrowKlass klass);
747
748 JFR_ONLY(DEFINE_TRACE_ID_METHODS;)
749
750 virtual void metaspace_pointers_do(MetaspaceClosure* iter);
751 virtual MetaspaceObj::Type type() const { return ClassType; }
752
753 inline bool is_loader_alive() const;
754 inline bool is_loader_present_and_alive() const;
755
756 void clean_subklass();
757
758 // Clean out unnecessary weak klass links from the whole klass hierarchy.
759 static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true);
760 // Clean out unnecessary weak klass links from the given InstanceKlass.
761 static void clean_weak_instanceklass_links(InstanceKlass* ik);
762
763 // Return self, except for abstract classes with exactly 1
764 // implementor. Then return the 1 concrete implementation.
765 Klass *up_cast_abstract();
766
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