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
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 };
393 static ByteSize secondary_supers_offset() { return byte_offset_of(Klass, _secondary_supers); }
394 static ByteSize java_mirror_offset() { return byte_offset_of(Klass, _java_mirror); }
395 static ByteSize class_loader_data_offset() { return byte_offset_of(Klass, _class_loader_data); }
396 static ByteSize modifier_flags_offset() { return byte_offset_of(Klass, _modifier_flags); }
397 static ByteSize layout_helper_offset() { return byte_offset_of(Klass, _layout_helper); }
398 static ByteSize access_flags_offset() { return byte_offset_of(Klass, _access_flags); }
399 #if INCLUDE_JVMCI
400 static ByteSize subklass_offset() { return byte_offset_of(Klass, _subklass); }
401 static ByteSize next_sibling_offset() { return byte_offset_of(Klass, _next_sibling); }
402 #endif
403
404 // Unpacking layout_helper:
405 static const int _lh_neutral_value = 0; // neutral non-array non-instance value
406 static const int _lh_instance_slow_path_bit = 0x01;
407 static const int _lh_log2_element_size_shift = BitsPerByte*0;
408 static const int _lh_log2_element_size_mask = BitsPerLong-1;
409 static const int _lh_element_type_shift = BitsPerByte*1;
410 static const int _lh_element_type_mask = right_n_bits(BitsPerByte); // shifted mask
411 static const int _lh_header_size_shift = BitsPerByte*2;
412 static const int _lh_header_size_mask = right_n_bits(BitsPerByte); // shifted mask
413 static const int _lh_array_tag_bits = 2;
414 static const int _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits;
415 static const int _lh_array_tag_obj_value = ~0x01; // 0x80000000 >> 30
416
417 static const unsigned int _lh_array_tag_type_value = 0Xffffffff; // ~0x00, // 0xC0000000 >> 30
418
419 static int layout_helper_size_in_bytes(jint lh) {
420 assert(lh > (jint)_lh_neutral_value, "must be instance");
421 return (int) lh & ~_lh_instance_slow_path_bit;
422 }
423 static bool layout_helper_needs_slow_path(jint lh) {
424 assert(lh > (jint)_lh_neutral_value, "must be instance");
425 return (lh & _lh_instance_slow_path_bit) != 0;
426 }
427 static bool layout_helper_is_instance(jint lh) {
428 return (jint)lh > (jint)_lh_neutral_value;
429 }
430 static bool layout_helper_is_array(jint lh) {
431 return (jint)lh < (jint)_lh_neutral_value;
432 }
433 static bool layout_helper_is_typeArray(jint lh) {
434 // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
435 return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
436 }
437 static bool layout_helper_is_objArray(jint lh) {
438 // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
439 return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
440 }
441 static int layout_helper_header_size(jint lh) {
442 assert(lh < (jint)_lh_neutral_value, "must be array");
443 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
444 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
445 return hsize;
446 }
447 static BasicType layout_helper_element_type(jint lh) {
448 assert(lh < (jint)_lh_neutral_value, "must be array");
449 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
450 assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
451 return (BasicType) btvalue;
452 }
453
454 // Want a pattern to quickly diff against layout header in register
455 // find something less clever!
456 static int layout_helper_boolean_diffbit() {
457 jint zlh = array_layout_helper(T_BOOLEAN);
458 jint blh = array_layout_helper(T_BYTE);
459 assert(zlh != blh, "array layout helpers must differ");
460 int diffbit = 1;
461 while ((diffbit & (zlh ^ blh)) == 0 && (diffbit & zlh) == 0) {
462 diffbit <<= 1;
463 assert(diffbit != 0, "make sure T_BOOLEAN has a different bit than T_BYTE");
464 }
465 return diffbit;
466 }
467
468 static int layout_helper_log2_element_size(jint lh) {
469 assert(lh < (jint)_lh_neutral_value, "must be array");
470 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
471 assert(l2esz <= LogBytesPerLong,
472 "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh);
473 return l2esz;
474 }
475 static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
476 return (tag << _lh_array_tag_shift)
477 | (hsize << _lh_header_size_shift)
478 | ((int)etype << _lh_element_type_shift)
479 | (log2_esize << _lh_log2_element_size_shift);
480 }
481 static jint instance_layout_helper(jint size, bool slow_path_flag) {
482 return (size << LogBytesPerWord)
483 | (slow_path_flag ? _lh_instance_slow_path_bit : 0);
484 }
485 static int layout_helper_to_size_helper(jint lh) {
486 assert(lh > (jint)_lh_neutral_value, "must be instance");
487 // Note that the following expression discards _lh_instance_slow_path_bit.
488 return lh >> LogBytesPerWord;
489 }
490 // Out-of-line version computes everything based on the etype:
491 static jint array_layout_helper(BasicType etype);
492
493 // What is the maximum number of primary superclasses any klass can have?
494 static juint primary_super_limit() { return _primary_super_limit; }
495
496 // vtables
609 // Returns the name for a class (Resource allocated) as the class
610 // would appear in a signature.
611 // For arrays, this returns the name of the element with a leading '['.
612 // For classes, this returns the name with a leading 'L' and a trailing ';'
613 // and the package separators as '/'.
614 virtual const char* signature_name() const;
615
616 const char* joint_in_module_of_loader(const Klass* class2, bool include_parent_loader = false) const;
617 const char* class_in_module_of_loader(bool use_are = false, bool include_parent_loader = false) const;
618
619 // Returns "interface", "abstract class" or "class".
620 const char* external_kind() const;
621
622 // type testing operations
623 #ifdef ASSERT
624 protected:
625 virtual bool is_instance_klass_slow() const { return false; }
626 virtual bool is_array_klass_slow() const { return false; }
627 virtual bool is_objArray_klass_slow() const { return false; }
628 virtual bool is_typeArray_klass_slow() const { return false; }
629 #endif // ASSERT
630 public:
631
632 // Fast non-virtual versions
633 #ifndef ASSERT
634 #define assert_same_query(xval, xcheck) xval
635 #else
636 private:
637 static bool assert_same_query(bool xval, bool xslow) {
638 assert(xval == xslow, "slow and fast queries agree");
639 return xval;
640 }
641 public:
642 #endif
643
644 bool is_instance_klass() const { return assert_same_query(_kind <= InstanceStackChunkKlassKind, is_instance_klass_slow()); }
645 // Other is anything that is not one of the more specialized kinds of InstanceKlass.
646 bool is_other_instance_klass() const { return _kind == InstanceKlassKind; }
647 bool is_reference_instance_klass() const { return _kind == InstanceRefKlassKind; }
648 bool is_mirror_instance_klass() const { return _kind == InstanceMirrorKlassKind; }
649 bool is_class_loader_instance_klass() const { return _kind == InstanceClassLoaderKlassKind; }
650 bool is_array_klass() const { return assert_same_query( _kind >= TypeArrayKlassKind, is_array_klass_slow()); }
651 bool is_stack_chunk_instance_klass() const { return _kind == InstanceStackChunkKlassKind; }
652 bool is_objArray_klass() const { return assert_same_query( _kind == ObjArrayKlassKind, is_objArray_klass_slow()); }
653 bool is_typeArray_klass() const { return assert_same_query( _kind == TypeArrayKlassKind, is_typeArray_klass_slow()); }
654 #undef assert_same_query
655
656 // Access flags
657 AccessFlags access_flags() const { return _access_flags; }
658 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
659
660 bool is_public() const { return _access_flags.is_public(); }
661 bool is_final() const { return _access_flags.is_final(); }
662 bool is_interface() const { return _access_flags.is_interface(); }
663 bool is_abstract() const { return _access_flags.is_abstract(); }
664 bool is_super() const { return _access_flags.is_super(); }
665 bool is_synthetic() const { return _access_flags.is_synthetic(); }
666 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
667 bool has_finalizer() const { return _access_flags.has_finalizer(); }
668 void set_has_finalizer() { _access_flags.set_has_finalizer(); }
669 bool is_hidden() const { return access_flags().is_hidden_class(); }
670 void set_is_hidden() { _access_flags.set_is_hidden_class(); }
671 bool is_value_based() { return _access_flags.is_value_based_class(); }
672 void set_is_value_based() { _access_flags.set_is_value_based_class(); }
673
674 inline bool is_non_strong_hidden() const;
675
676 bool is_cloneable() const;
677 void set_is_cloneable();
678
679 JFR_ONLY(DEFINE_TRACE_ID_METHODS;)
680
681 virtual void metaspace_pointers_do(MetaspaceClosure* iter);
682 virtual MetaspaceObj::Type type() const { return ClassType; }
683
684 inline bool is_loader_alive() const;
685
686 void clean_subklass();
687
688 static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true);
689 static void clean_subklass_tree() {
690 clean_weak_klass_links(/*unloading_occurred*/ true , /* clean_alive_klasses */ false);
691 }
692
693 // Return self, except for abstract classes with exactly 1
694 // implementor. Then return the 1 concrete implementation.
695 Klass *up_cast_abstract();
696
697 // klass name
698 Symbol* name() const { return _name; }
|
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 InlineKlassKind,
74 InstanceRefKlassKind,
75 InstanceMirrorKlassKind,
76 InstanceClassLoaderKlassKind,
77 InstanceStackChunkKlassKind,
78 TypeArrayKlassKind,
79 FlatArrayKlassKind,
80 ObjArrayKlassKind,
81 UnknownKlassKind
82 };
83
84 static const uint KLASS_KIND_COUNT = ObjArrayKlassKind + 1;
85 protected:
86
87 // If you add a new field that points to any metaspace object, you
88 // must add this field to Klass::metaspace_pointers_do().
89
90 // note: put frequently-used fields together at start of klass structure
91 // for better cache behavior (may not make much of a difference but sure won't hurt)
92 enum { _primary_super_limit = 8 };
93
94 // The "layout helper" is a combined descriptor of object layout.
95 // For klasses which are neither instance nor array, the value is zero.
96 //
97 // For instances, layout helper is a positive number, the instance size.
98 // This size is already passed through align_object_size and scaled to bytes.
99 // The low order bit is set if instances of this class cannot be
100 // allocated using the fastpath.
101 //
102 // For arrays, layout helper is a negative number, containing four
103 // distinct bytes, as follows:
104 // MSB:[tag, hsz, ebt, log2(esz)]:LSB
105 // where:
106 // tag is 0x80 if the elements are oops, 0xC0 if non-oops, 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
152 // First subclass (null if none); _subklass->next_sibling() is next one
153 Klass* volatile _subklass;
154 // Sibling link (or null); links all subklasses of a klass
155 Klass* volatile _next_sibling;
156
157 // All klasses loaded by a class loader are chained through these links
158 Klass* _next_link;
159
160 // The VM's representation of the ClassLoader used to load this class.
161 // Provide access the corresponding instance java.lang.ClassLoader.
162 ClassLoaderData* _class_loader_data;
163
164 int _vtable_len; // vtable length. This field may be read very often when we
165 // have lots of itable dispatches (e.g., lambdas and streams).
166 // Keep it away from the beginning of a Klass to avoid cacheline
167 // contention that may happen when a nearby object is modified.
168 AccessFlags _access_flags; // Access flags. The class/interface distinction is stored here.
169
170 JFR_ONLY(DEFINE_TRACE_ID_FIELD;)
171
172 markWord _prototype_header; // inline type and inline array mark patterns
173 private:
174 // This is an index into FileMapHeader::_shared_path_table[], to
175 // associate this class with the JAR file where it's loaded from during
176 // dump time. If a class is not loaded from the shared archive, this field is
177 // -1.
178 s2 _shared_class_path_index;
179
180 #if INCLUDE_CDS
181 // Various attributes for shared classes. Should be zero for a non-shared class.
182 u2 _shared_class_flags;
183 enum CDSSharedClassFlags {
184 _is_shared_class = 1 << 0, // shadows MetaspaceObj::is_shared
185 _archived_lambda_proxy_is_available = 1 << 1,
186 _has_value_based_class_annotation = 1 << 2,
187 _verified_at_dump_time = 1 << 3,
188 _has_archived_enum_objs = 1 << 4,
189 // This class was not loaded from a classfile in the module image
190 // or classpath.
191 _is_generated_shared_class = 1 << 5
192 };
396 static ByteSize secondary_supers_offset() { return byte_offset_of(Klass, _secondary_supers); }
397 static ByteSize java_mirror_offset() { return byte_offset_of(Klass, _java_mirror); }
398 static ByteSize class_loader_data_offset() { return byte_offset_of(Klass, _class_loader_data); }
399 static ByteSize modifier_flags_offset() { return byte_offset_of(Klass, _modifier_flags); }
400 static ByteSize layout_helper_offset() { return byte_offset_of(Klass, _layout_helper); }
401 static ByteSize access_flags_offset() { return byte_offset_of(Klass, _access_flags); }
402 #if INCLUDE_JVMCI
403 static ByteSize subklass_offset() { return byte_offset_of(Klass, _subklass); }
404 static ByteSize next_sibling_offset() { return byte_offset_of(Klass, _next_sibling); }
405 #endif
406
407 // Unpacking layout_helper:
408 static const int _lh_neutral_value = 0; // neutral non-array non-instance value
409 static const int _lh_instance_slow_path_bit = 0x01;
410 static const int _lh_log2_element_size_shift = BitsPerByte*0;
411 static const int _lh_log2_element_size_mask = BitsPerLong-1;
412 static const int _lh_element_type_shift = BitsPerByte*1;
413 static const int _lh_element_type_mask = right_n_bits(BitsPerByte); // shifted mask
414 static const int _lh_header_size_shift = BitsPerByte*2;
415 static const int _lh_header_size_mask = right_n_bits(BitsPerByte); // shifted mask
416 static const int _lh_array_tag_bits = 3;
417 static const int _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits;
418
419 static const unsigned int _lh_array_tag_type_value = 0Xfffffffc;
420 static const unsigned int _lh_array_tag_vt_value = 0Xfffffffd;
421 static const unsigned int _lh_array_tag_obj_value = 0Xfffffffe;
422
423 // null-free array flag bit under the array tag bits, shift one more to get array tag value
424 static const int _lh_null_free_shift = _lh_array_tag_shift - 1;
425 static const int _lh_null_free_mask = 1;
426
427 static const jint _lh_array_tag_flat_value_bit_inplace = (jint) (1 << _lh_array_tag_shift);
428 static const jint _lh_null_free_array_bit_inplace = (jint) (_lh_null_free_mask << _lh_null_free_shift);
429
430 static int layout_helper_size_in_bytes(jint lh) {
431 assert(lh > (jint)_lh_neutral_value, "must be instance");
432 return (int) lh & ~_lh_instance_slow_path_bit;
433 }
434 static bool layout_helper_needs_slow_path(jint lh) {
435 assert(lh > (jint)_lh_neutral_value, "must be instance");
436 return (lh & _lh_instance_slow_path_bit) != 0;
437 }
438 static bool layout_helper_is_instance(jint lh) {
439 return (jint)lh > (jint)_lh_neutral_value;
440 }
441 static bool layout_helper_is_array(jint lh) {
442 return (jint)lh < (jint)_lh_neutral_value;
443 }
444 static bool layout_helper_is_typeArray(jint lh) {
445 return (juint) _lh_array_tag_type_value == (juint)(lh >> _lh_array_tag_shift);
446 }
447 static bool layout_helper_is_objArray(jint lh) {
448 return (juint)_lh_array_tag_obj_value == (juint)(lh >> _lh_array_tag_shift);
449 }
450 static bool layout_helper_is_flatArray(jint lh) {
451 return (juint)_lh_array_tag_vt_value == (juint)(lh >> _lh_array_tag_shift);
452 }
453 static bool layout_helper_is_null_free(jint lh) {
454 assert(layout_helper_is_flatArray(lh) || layout_helper_is_objArray(lh), "must be array of inline types");
455 return ((lh >> _lh_null_free_shift) & _lh_null_free_mask);
456 }
457 static jint layout_helper_set_null_free(jint lh) {
458 lh |= (_lh_null_free_mask << _lh_null_free_shift);
459 assert(layout_helper_is_null_free(lh), "Bad encoding");
460 return lh;
461 }
462 static int layout_helper_header_size(jint lh) {
463 assert(lh < (jint)_lh_neutral_value, "must be array");
464 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
465 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
466 return hsize;
467 }
468 static BasicType layout_helper_element_type(jint lh) {
469 assert(lh < (jint)_lh_neutral_value, "must be array");
470 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
471 assert((btvalue >= T_BOOLEAN && btvalue <= T_OBJECT) || btvalue == T_PRIMITIVE_OBJECT, "sanity");
472 return (BasicType) btvalue;
473 }
474
475 // Want a pattern to quickly diff against layout header in register
476 // find something less clever!
477 static int layout_helper_boolean_diffbit() {
478 jint zlh = array_layout_helper(T_BOOLEAN);
479 jint blh = array_layout_helper(T_BYTE);
480 assert(zlh != blh, "array layout helpers must differ");
481 int diffbit = 1;
482 while ((diffbit & (zlh ^ blh)) == 0 && (diffbit & zlh) == 0) {
483 diffbit <<= 1;
484 assert(diffbit != 0, "make sure T_BOOLEAN has a different bit than T_BYTE");
485 }
486 return diffbit;
487 }
488
489 static int layout_helper_log2_element_size(jint lh) {
490 assert(lh < (jint)_lh_neutral_value, "must be array");
491 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
492 assert(layout_helper_element_type(lh) == T_PRIMITIVE_OBJECT || l2esz <= LogBytesPerLong,
493 "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh);
494 return l2esz;
495 }
496 static jint array_layout_helper(jint tag, bool null_free, int hsize, BasicType etype, int log2_esize) {
497 return (tag << _lh_array_tag_shift)
498 | ((null_free ? 1 : 0) << _lh_null_free_shift)
499 | (hsize << _lh_header_size_shift)
500 | ((int)etype << _lh_element_type_shift)
501 | (log2_esize << _lh_log2_element_size_shift);
502 }
503 static jint instance_layout_helper(jint size, bool slow_path_flag) {
504 return (size << LogBytesPerWord)
505 | (slow_path_flag ? _lh_instance_slow_path_bit : 0);
506 }
507 static int layout_helper_to_size_helper(jint lh) {
508 assert(lh > (jint)_lh_neutral_value, "must be instance");
509 // Note that the following expression discards _lh_instance_slow_path_bit.
510 return lh >> LogBytesPerWord;
511 }
512 // Out-of-line version computes everything based on the etype:
513 static jint array_layout_helper(BasicType etype);
514
515 // What is the maximum number of primary superclasses any klass can have?
516 static juint primary_super_limit() { return _primary_super_limit; }
517
518 // vtables
631 // Returns the name for a class (Resource allocated) as the class
632 // would appear in a signature.
633 // For arrays, this returns the name of the element with a leading '['.
634 // For classes, this returns the name with a leading 'L' and a trailing ';'
635 // and the package separators as '/'.
636 virtual const char* signature_name() const;
637
638 const char* joint_in_module_of_loader(const Klass* class2, bool include_parent_loader = false) const;
639 const char* class_in_module_of_loader(bool use_are = false, bool include_parent_loader = false) const;
640
641 // Returns "interface", "abstract class" or "class".
642 const char* external_kind() const;
643
644 // type testing operations
645 #ifdef ASSERT
646 protected:
647 virtual bool is_instance_klass_slow() const { return false; }
648 virtual bool is_array_klass_slow() const { return false; }
649 virtual bool is_objArray_klass_slow() const { return false; }
650 virtual bool is_typeArray_klass_slow() const { return false; }
651 virtual bool is_flatArray_klass_slow() const { return false; }
652 #endif // ASSERT
653 // current implementation uses this method even in non debug builds
654 virtual bool is_inline_klass_slow() const { return false; }
655 public:
656
657 // Fast non-virtual versions
658 #ifndef ASSERT
659 #define assert_same_query(xval, xcheck) xval
660 #else
661 private:
662 static bool assert_same_query(bool xval, bool xslow) {
663 assert(xval == xslow, "slow and fast queries agree");
664 return xval;
665 }
666 public:
667 #endif
668
669 bool is_instance_klass() const { return assert_same_query(_kind <= InstanceStackChunkKlassKind, is_instance_klass_slow()); }
670 bool is_inline_klass() const { return is_inline_klass_slow(); } //temporary hack
671 // Other is anything that is not one of the more specialized kinds of InstanceKlass.
672 bool is_other_instance_klass() const { return _kind <= InlineKlassKind; }
673 bool is_reference_instance_klass() const { return _kind == InstanceRefKlassKind; }
674 bool is_mirror_instance_klass() const { return _kind == InstanceMirrorKlassKind; }
675 bool is_class_loader_instance_klass() const { return _kind == InstanceClassLoaderKlassKind; }
676 bool is_array_klass() const { return assert_same_query( _kind >= TypeArrayKlassKind, is_array_klass_slow()); }
677 bool is_stack_chunk_instance_klass() const { return _kind == InstanceStackChunkKlassKind; }
678 bool is_flatArray_klass() const { return assert_same_query( _kind == FlatArrayKlassKind, is_flatArray_klass_slow()); }
679 bool is_objArray_klass() const { return assert_same_query( _kind == ObjArrayKlassKind, is_objArray_klass_slow()); }
680 bool is_typeArray_klass() const { return assert_same_query( _kind == TypeArrayKlassKind, is_typeArray_klass_slow()); }
681 #undef assert_same_query
682
683 inline bool is_null_free_array_klass() const { return layout_helper_is_null_free(layout_helper()); }
684
685 // Access flags
686 AccessFlags access_flags() const { return _access_flags; }
687 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
688
689 bool is_public() const { return _access_flags.is_public(); }
690 bool is_final() const { return _access_flags.is_final(); }
691 bool is_interface() const { return _access_flags.is_interface(); }
692 bool is_abstract() const { return _access_flags.is_abstract(); }
693 bool is_synthetic() const { return _access_flags.is_synthetic(); }
694 bool is_value_class() const { return _access_flags.is_value_class(); }
695 bool is_identity_class() const { return _access_flags.is_identity_class(); }
696 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
697 bool has_finalizer() const { return _access_flags.has_finalizer(); }
698 void set_has_finalizer() { _access_flags.set_has_finalizer(); }
699 bool is_hidden() const { return access_flags().is_hidden_class(); }
700 void set_is_hidden() { _access_flags.set_is_hidden_class(); }
701 bool is_value_based() { return _access_flags.is_value_based_class(); }
702 void set_is_value_based() { _access_flags.set_is_value_based_class(); }
703
704 inline bool is_non_strong_hidden() const;
705
706 bool is_cloneable() const;
707 void set_is_cloneable();
708
709 // inline types and inline type array patterns
710 markWord prototype_header() const {
711 return _prototype_header;
712 }
713 static inline markWord default_prototype_header(Klass* k) {
714 return (k == nullptr) ? markWord::prototype() : k->prototype_header();
715 }
716
717 inline void set_prototype_header(markWord header);
718 static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); }
719
720 JFR_ONLY(DEFINE_TRACE_ID_METHODS;)
721
722 virtual void metaspace_pointers_do(MetaspaceClosure* iter);
723 virtual MetaspaceObj::Type type() const { return ClassType; }
724
725 inline bool is_loader_alive() const;
726
727 void clean_subklass();
728
729 static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true);
730 static void clean_subklass_tree() {
731 clean_weak_klass_links(/*unloading_occurred*/ true , /* clean_alive_klasses */ false);
732 }
733
734 // Return self, except for abstract classes with exactly 1
735 // implementor. Then return the 1 concrete implementation.
736 Klass *up_cast_abstract();
737
738 // klass name
739 Symbol* name() const { return _name; }
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