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
187 // no further need to call <clinit>
188 _has_aot_safe_initializer = 1 << 7, // has @AOTSafeClassInitializer annotation
189 _is_runtime_setup_required = 1 << 8, // has a runtimeSetup method to be called when
190 // this class is loaded from AOT cache
191 };
192 #endif
193
194 int _vtable_len; // vtable length. This field may be read very often when we
195 // have lots of itable dispatches (e.g., lambdas and streams).
196 // Keep it away from the beginning of a Klass to avoid cacheline
197 // contention that may happen when a nearby object is modified.
198
199 CDS_JAVA_HEAP_ONLY(int _archived_mirror_index;)
200
201 public:
202
203 JFR_ONLY(DEFINE_TRACE_ID_FIELD;)
204
205 protected:
206
207 Klass(KlassKind kind);
208 Klass();
209
210 void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw();
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; }
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
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_typeArray_klass_slow() const { return false; }
682 #endif // ASSERT
683 public:
684
685 // Fast non-virtual versions
686 #ifndef ASSERT
687 #define assert_same_query(xval, xcheck) xval
688 #else
689 private:
690 static bool assert_same_query(bool xval, bool xslow) {
691 assert(xval == xslow, "slow and fast queries agree");
692 return xval;
693 }
694 public:
695 #endif
696
697 bool is_instance_klass() const { return assert_same_query(_kind <= InstanceStackChunkKlassKind, is_instance_klass_slow()); }
698 // Other is anything that is not one of the more specialized kinds of InstanceKlass.
699 bool is_other_instance_klass() const { return _kind == InstanceKlassKind; }
700 bool is_reference_instance_klass() const { return _kind == InstanceRefKlassKind; }
701 bool is_mirror_instance_klass() const { return _kind == InstanceMirrorKlassKind; }
702 bool is_class_loader_instance_klass() const { return _kind == InstanceClassLoaderKlassKind; }
703 bool is_array_klass() const { return assert_same_query( _kind >= TypeArrayKlassKind, is_array_klass_slow()); }
704 bool is_stack_chunk_instance_klass() const { return _kind == InstanceStackChunkKlassKind; }
705 bool is_objArray_klass() const { return assert_same_query( _kind == ObjArrayKlassKind, is_objArray_klass_slow()); }
706 bool is_typeArray_klass() const { return assert_same_query( _kind == TypeArrayKlassKind, is_typeArray_klass_slow()); }
707 #undef assert_same_query
708
709 // Access flags
710 AccessFlags access_flags() const { return _access_flags; }
711 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
712
713 bool is_public() const { return _access_flags.is_public(); }
714 bool is_final() const { return _access_flags.is_final(); }
715 bool is_interface() const { return _access_flags.is_interface(); }
716 bool is_abstract() const { return _access_flags.is_abstract(); }
717 bool is_super() const { return _access_flags.is_super(); }
718 bool is_synthetic() const { return _access_flags.is_synthetic(); }
719 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
720 bool has_finalizer() const { return _misc_flags.has_finalizer(); }
721 void set_has_finalizer() { _misc_flags.set_has_finalizer(true); }
722 bool is_hidden() const { return _misc_flags.is_hidden_class(); }
723 void set_is_hidden() { _misc_flags.set_is_hidden_class(true); }
724 bool is_value_based() const { return _misc_flags.is_value_based_class(); }
725 void set_is_value_based() { _misc_flags.set_is_value_based_class(true); }
726
727 klass_flags_t misc_flags() const { return _misc_flags.value(); }
728
729 inline bool is_non_strong_hidden() const;
730
731 bool is_cloneable() const;
732 void set_is_cloneable();
733
734 inline markWord prototype_header() const;
735 inline void set_prototype_header(markWord header);
736 static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); }
737
738 JFR_ONLY(DEFINE_TRACE_ID_METHODS;)
739
740 virtual void metaspace_pointers_do(MetaspaceClosure* iter);
741 virtual MetaspaceObj::Type type() const { return ClassType; }
742
743 inline bool is_loader_alive() const;
744 inline bool is_loader_present_and_alive() const;
745
746 Klass* clean_subklass(bool log = false);
747
748 // Clean out unnecessary weak klass links from the whole klass hierarchy.
749 static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true);
750 // Clean out unnecessary weak klass links from the given InstanceKlass.
751 static void clean_weak_instanceklass_links(InstanceKlass* ik);
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
|
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
191 // no further need to call <clinit>
192 _has_aot_safe_initializer = 1 << 7, // has @AOTSafeClassInitializer annotation
193 _is_runtime_setup_required = 1 << 8, // has a runtimeSetup method to be called when
194 // this class is loaded from AOT cache
195 };
196 #endif
197
198 int _vtable_len; // vtable length. This field may be read very often when we
199 // have lots of itable dispatches (e.g., lambdas and streams).
200 // Keep it away from the beginning of a Klass to avoid cacheline
201 // contention that may happen when a nearby object is modified.
202
203 CDS_JAVA_HEAP_ONLY(int _archived_mirror_index;)
204
205 public:
206
207 JFR_ONLY(DEFINE_TRACE_ID_FIELD;)
208
209 protected:
210
211 Klass(KlassKind kind, markWord prototype_header = markWord::prototype());
212 Klass();
213
214 void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw();
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:
229 // - Klass::java_super() - if you have a Klass*
230 // - InstanceKlass::super() - if you have an InstanceKlass* ik, ik->super() returns InstanceKlass*.
231 Klass* super() const { return _super; }
459 static ByteSize layout_helper_offset() { return byte_offset_of(Klass, _layout_helper); }
460 static ByteSize access_flags_offset() { return byte_offset_of(Klass, _access_flags); }
461 #if INCLUDE_JVMCI
462 static ByteSize subklass_offset() { return byte_offset_of(Klass, _subklass); }
463 static ByteSize next_sibling_offset() { return byte_offset_of(Klass, _next_sibling); }
464 #endif
465 static ByteSize secondary_supers_bitmap_offset()
466 { return byte_offset_of(Klass, _secondary_supers_bitmap); }
467 static ByteSize hash_slot_offset() { return byte_offset_of(Klass, _hash_slot); }
468 static ByteSize misc_flags_offset() { return byte_offset_of(Klass, _misc_flags._flags); }
469
470 // Unpacking layout_helper:
471 static const int _lh_neutral_value = 0; // neutral non-array non-instance value
472 static const int _lh_instance_slow_path_bit = 0x01;
473 static const int _lh_log2_element_size_shift = BitsPerByte*0;
474 static const int _lh_log2_element_size_mask = BitsPerLong-1;
475 static const int _lh_element_type_shift = BitsPerByte*1;
476 static const int _lh_element_type_mask = right_n_bits(BitsPerByte); // shifted mask
477 static const int _lh_header_size_shift = BitsPerByte*2;
478 static const int _lh_header_size_mask = right_n_bits(BitsPerByte); // shifted mask
479 static const int _lh_array_tag_bits = 4;
480 static const int _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits;
481
482 static const unsigned int _lh_array_tag_type_value = 0Xfffffffc;
483 static const unsigned int _lh_array_tag_flat_value = 0Xfffffffa;
484 static const unsigned int _lh_array_tag_ref_value = 0Xfffffff8;
485
486 // null-free array flag bit under the array tag bits, shift one more to get array tag value
487 static const int _lh_null_free_shift = _lh_array_tag_shift - 1;
488 static const int _lh_null_free_mask = 1;
489
490 static const jint _lh_array_tag_flat_value_bit_inplace = (jint) (1 << (_lh_array_tag_shift + 1));
491
492 static int layout_helper_size_in_bytes(jint lh) {
493 assert(lh > (jint)_lh_neutral_value, "must be instance");
494 return (int) lh & ~_lh_instance_slow_path_bit;
495 }
496 static bool layout_helper_needs_slow_path(jint lh) {
497 assert(lh > (jint)_lh_neutral_value, "must be instance");
498 return (lh & _lh_instance_slow_path_bit) != 0;
499 }
500 static bool layout_helper_is_instance(jint lh) {
501 return (jint)lh > (jint)_lh_neutral_value;
502 }
503 static bool layout_helper_is_array(jint lh) {
504 return (jint)lh < (jint)_lh_neutral_value;
505 }
506 static bool layout_helper_is_typeArray(jint lh) {
507 return (juint) _lh_array_tag_type_value == (juint)(lh >> _lh_array_tag_shift);
508 }
509 static bool layout_helper_is_refArray(jint lh) {
510 return (juint)_lh_array_tag_ref_value == (juint)(lh >> _lh_array_tag_shift);
511 }
512 static bool layout_helper_is_flatArray(jint lh) {
513 return (juint)_lh_array_tag_flat_value == (juint)(lh >> _lh_array_tag_shift);
514 }
515 static bool layout_helper_is_null_free(jint lh) {
516 assert(layout_helper_is_flatArray(lh) || layout_helper_is_refArray(lh), "must be array of inline types");
517 return ((lh >> _lh_null_free_shift) & _lh_null_free_mask);
518 }
519 static jint layout_helper_set_null_free(jint lh) {
520 lh |= (_lh_null_free_mask << _lh_null_free_shift);
521 assert(layout_helper_is_null_free(lh), "Bad encoding");
522 return lh;
523 }
524 static int layout_helper_header_size(jint lh) {
525 assert(lh < (jint)_lh_neutral_value, "must be array");
526 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
527 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
528 return hsize;
529 }
530 static BasicType layout_helper_element_type(jint lh) {
531 assert(lh < (jint)_lh_neutral_value, "must be array");
532 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
533 assert((btvalue >= T_BOOLEAN && btvalue <= T_OBJECT) || btvalue == T_FLAT_ELEMENT, "sanity");
534 return (BasicType) btvalue;
535 }
536
537 // Want a pattern to quickly diff against layout header in register
538 // find something less clever!
539 static int layout_helper_boolean_diffbit() {
540 jint zlh = array_layout_helper(T_BOOLEAN);
541 jint blh = array_layout_helper(T_BYTE);
542 assert(zlh != blh, "array layout helpers must differ");
543 int diffbit = 1;
544 while ((diffbit & (zlh ^ blh)) == 0 && (diffbit & zlh) == 0) {
545 diffbit <<= 1;
546 assert(diffbit != 0, "make sure T_BOOLEAN has a different bit than T_BYTE");
547 }
548 return diffbit;
549 }
550
551 static int layout_helper_log2_element_size(jint lh) {
552 assert(lh < (jint)_lh_neutral_value, "must be array");
553 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
554 assert(layout_helper_element_type(lh) == T_FLAT_ELEMENT || l2esz <= LogBytesPerLong,
555 "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh);
556 return l2esz;
557 }
558 static jint array_layout_helper(jint tag, bool null_free, int hsize, BasicType etype, int log2_esize) {
559 return (tag << _lh_array_tag_shift)
560 | ((null_free ? 1 : 0) << _lh_null_free_shift)
561 | (hsize << _lh_header_size_shift)
562 | ((int)etype << _lh_element_type_shift)
563 | (log2_esize << _lh_log2_element_size_shift);
564 }
565 static jint instance_layout_helper(jint size, bool slow_path_flag) {
566 return (size << LogBytesPerWord)
567 | (slow_path_flag ? _lh_instance_slow_path_bit : 0);
568 }
569 static int layout_helper_to_size_helper(jint lh) {
570 assert(lh > (jint)_lh_neutral_value, "must be instance");
571 // Note that the following expression discards _lh_instance_slow_path_bit.
572 return lh >> LogBytesPerWord;
573 }
574 // Out-of-line version computes everything based on the etype:
575 static jint array_layout_helper(BasicType etype);
576
577 // What is the maximum number of primary superclasses any klass can have?
578 static juint primary_super_limit() { return _primary_super_limit; }
579
580 // vtables
683 const char* external_name() const;
684 // Returns the name for a class (Resource allocated) as the class
685 // would appear in a signature.
686 // For arrays, this returns the name of the element with a leading '['.
687 // For classes, this returns the name with a leading 'L' and a trailing ';'
688 // and the package separators as '/'.
689 virtual const char* signature_name() const;
690
691 const char* joint_in_module_of_loader(const Klass* class2, bool include_parent_loader = false) const;
692 const char* class_in_module_of_loader(bool use_are = false, bool include_parent_loader = false) const;
693
694 // Returns "interface", "abstract class" or "class".
695 const char* external_kind() const;
696
697 // type testing operations
698 #ifdef ASSERT
699 protected:
700 virtual bool is_instance_klass_slow() const { return false; }
701 virtual bool is_array_klass_slow() const { return false; }
702 virtual bool is_objArray_klass_slow() const { return false; }
703 virtual bool is_refArray_klass_slow() const { return false; }
704 virtual bool is_typeArray_klass_slow() const { return false; }
705 virtual bool is_flatArray_klass_slow() const { return false; }
706 #endif // ASSERT
707 // current implementation uses this method even in non debug builds
708 virtual bool is_inline_klass_slow() const { return false; }
709 public:
710
711 // Fast non-virtual versions
712 #ifndef ASSERT
713 #define assert_same_query(xval, xcheck) xval
714 #else
715 private:
716 static bool assert_same_query(bool xval, bool xslow) {
717 assert(xval == xslow, "slow and fast queries agree");
718 return xval;
719 }
720 public:
721 #endif
722
723 bool is_instance_klass() const { return assert_same_query(_kind <= InstanceStackChunkKlassKind, is_instance_klass_slow()); }
724 bool is_inline_klass() const { return assert_same_query(_kind == InlineKlassKind, is_inline_klass_slow()); }
725 bool is_reference_instance_klass() const { return _kind == InstanceRefKlassKind; }
726 bool is_mirror_instance_klass() const { return _kind == InstanceMirrorKlassKind; }
727 bool is_class_loader_instance_klass() const { return _kind == InstanceClassLoaderKlassKind; }
728 bool is_array_klass() const { return assert_same_query( _kind >= TypeArrayKlassKind, is_array_klass_slow()); }
729 bool is_stack_chunk_instance_klass() const { return _kind == InstanceStackChunkKlassKind; }
730 bool is_flatArray_klass() const { return assert_same_query( _kind == FlatArrayKlassKind, is_flatArray_klass_slow()); }
731 bool is_objArray_klass() const { return assert_same_query( _kind == ObjArrayKlassKind || _kind == RefArrayKlassKind || _kind == FlatArrayKlassKind, is_objArray_klass_slow()); }
732 bool is_refArray_klass() const { return assert_same_query( _kind == RefArrayKlassKind, is_refArray_klass_slow()); }
733 bool is_typeArray_klass() const { return assert_same_query( _kind == TypeArrayKlassKind, is_typeArray_klass_slow()); }
734 bool is_refined_objArray_klass() const { return is_refArray_klass() || is_flatArray_klass(); }
735 #undef assert_same_query
736
737 inline bool is_null_free_array_klass() const { return !is_typeArray_klass() && layout_helper_is_null_free(layout_helper()); }
738
739 // Access flags
740 AccessFlags access_flags() const { return _access_flags; }
741 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
742
743 bool is_public() const { return _access_flags.is_public(); }
744 bool is_final() const { return _access_flags.is_final(); }
745 bool is_interface() const { return _access_flags.is_interface(); }
746 bool is_abstract() const { return _access_flags.is_abstract(); }
747 bool is_synthetic() const { return _access_flags.is_synthetic(); }
748 bool is_identity_class() const { assert(is_instance_klass(), "only for instanceKlass"); return _access_flags.is_identity_class(); }
749 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
750 bool has_finalizer() const { return _misc_flags.has_finalizer(); }
751 void set_has_finalizer() { _misc_flags.set_has_finalizer(true); }
752 bool is_hidden() const { return _misc_flags.is_hidden_class(); }
753 void set_is_hidden() { _misc_flags.set_is_hidden_class(true); }
754 bool is_value_based() const { return _misc_flags.is_value_based_class(); }
755 void set_is_value_based() { _misc_flags.set_is_value_based_class(true); }
756
757 klass_flags_t misc_flags() const { return _misc_flags.value(); }
758
759 inline bool is_non_strong_hidden() const;
760
761 bool is_cloneable() const;
762 void set_is_cloneable();
763
764 static inline markWord make_prototype_header(const Klass* kls, markWord prototype = markWord::prototype());
765 inline markWord prototype_header() const;
766 inline void set_prototype_header(markWord header);
767 static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); }
768 inline void set_prototype_header_klass(narrowKlass klass);
769
770 JFR_ONLY(DEFINE_TRACE_ID_METHODS;)
771
772 virtual void metaspace_pointers_do(MetaspaceClosure* iter);
773 virtual MetaspaceObj::Type type() const { return ClassType; }
774
775 inline bool is_loader_alive() const;
776 inline bool is_loader_present_and_alive() const;
777
778 Klass* clean_subklass(bool log = false);
779
780 // Clean out unnecessary weak klass links from the whole klass hierarchy.
781 static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true);
782 // Clean out unnecessary weak klass links from the given InstanceKlass.
783 static void clean_weak_instanceklass_links(InstanceKlass* ik);
784
785 // Return self, except for abstract classes with exactly 1
786 // implementor. Then return the 1 concrete implementation.
787 Klass *up_cast_abstract();
788
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