35 #include "jfr/support/jfrTraceIdExtension.hpp"
36 #endif
37
38 //
39 // A Klass provides:
40 // 1: language level class object (method dictionary etc.)
41 // 2: provide vm dispatch behavior for the object
42 // Both functions are combined into one C++ class.
43
44 // One reason for the oop/klass dichotomy in the implementation is
45 // that we don't want a C++ vtbl pointer in every object. Thus,
46 // normal oops don't have any virtual functions. Instead, they
47 // forward all "virtual" functions to their klass, which does have
48 // a vtbl and does the C++ dispatch depending on the object's
49 // actual type. (See oop.inline.hpp for some of the forwarding code.)
50 // ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"!
51
52 // Forward declarations.
53 template <class T> class Array;
54 template <class T> class GrowableArray;
55 class ClassLoaderData;
56 class fieldDescriptor;
57 class klassVtable;
58 class ModuleEntry;
59 class PackageEntry;
60 class vtableEntry;
61
62 class Klass : public Metadata {
63
64 friend class VMStructs;
65 public:
66 // Klass Kinds for all subclasses of Klass
67 enum KlassKind : u2 {
68 InstanceKlassKind,
69 InstanceRefKlassKind,
70 InstanceMirrorKlassKind,
71 InstanceClassLoaderKlassKind,
72 InstanceStackChunkKlassKind,
73 TypeArrayKlassKind,
74 ObjArrayKlassKind,
75 UnknownKlassKind
76 };
77
78 static const uint KLASS_KIND_COUNT = ObjArrayKlassKind + 1;
79 protected:
80
81 // If you add a new field that points to any metaspace object, you
82 // must add this field to Klass::metaspace_pointers_do().
83
84 // note: put frequently-used fields together at start of klass structure
85 // for better cache behavior (may not make much of a difference but sure won't hurt)
86 enum { _primary_super_limit = 8 };
87
88 // The "layout helper" is a combined descriptor of object layout.
89 // For klasses which are neither instance nor array, the value is zero.
90 //
91 // For instances, layout helper is a positive number, the instance size.
92 // This size is already passed through align_object_size and scaled to bytes.
93 // The low order bit is set if instances of this class cannot be
94 // allocated using the fastpath.
95 //
96 // For arrays, layout helper is a negative number, containing four
97 // distinct bytes, as follows:
98 // MSB:[tag, hsz, ebt, log2(esz)]:LSB
99 // where:
100 // tag is 0x80 if the elements are oops, 0xC0 if non-oops
101 // hsz is array header size in bytes (i.e., offset of first element)
102 // ebt is the BasicType of the elements
103 // esz is the element size in bytes
104 // This packed word is arranged so as to be quickly unpacked by the
105 // various fast paths that use the various subfields.
106 //
107 // The esz bits can be used directly by a SLL instruction, without masking.
108 //
109 // Note that the array-kind tag looks like 0x00 for instance klasses,
110 // since their length in bytes is always less than 24Mb.
111 //
112 // Final note: This comes first, immediately after C++ vtable,
113 // because it is frequently queried.
114 jint _layout_helper;
115
116 // Klass kind used to resolve the runtime type of the instance.
117 // - Used to implement devirtualized oop closure dispatching.
118 // - Various type checking in the JVM
119 const KlassKind _kind;
120
184 // no further need to call <clinit>
185 _has_aot_safe_initializer = 1 << 7, // has @AOTSafeClassInitializer annotation
186 _is_runtime_setup_required = 1 << 8, // has a runtimeSetup method to be called when
187 // this class is loaded from AOT cache
188 };
189 #endif
190
191 int _vtable_len; // vtable length. This field may be read very often when we
192 // have lots of itable dispatches (e.g., lambdas and streams).
193 // Keep it away from the beginning of a Klass to avoid cacheline
194 // contention that may happen when a nearby object is modified.
195
196 CDS_JAVA_HEAP_ONLY(int _archived_mirror_index;)
197
198 public:
199
200 JFR_ONLY(DEFINE_TRACE_ID_FIELD;)
201
202 protected:
203
204 Klass(KlassKind kind);
205 Klass();
206
207 void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw();
208
209 public:
210 int kind() { return _kind; }
211
212 enum class DefaultsLookupMode { find, skip };
213 enum class OverpassLookupMode { find, skip };
214 enum class StaticLookupMode { find, skip };
215 enum class PrivateLookupMode { find, skip };
216
217 bool is_klass() const override { return true; }
218
219 // super() cannot be InstanceKlass* -- Java arrays are covariant, and _super is used
220 // to implement that. NB: the _super of "[Ljava/lang/Integer;" is "[Ljava/lang/Number;"
221 // If this is not what your code expects, you're probably looking for:
222 // - Klass::java_super() - if you have a Klass*
223 // - InstanceKlass::super() - if you have an InstanceKlass* ik, ik->super() returns InstanceKlass*.
224 Klass* super() const { return _super; }
447 static ByteSize primary_supers_offset() { return byte_offset_of(Klass, _primary_supers); }
448 static ByteSize secondary_super_cache_offset() { return byte_offset_of(Klass, _secondary_super_cache); }
449 static ByteSize secondary_supers_offset() { return byte_offset_of(Klass, _secondary_supers); }
450 static ByteSize java_mirror_offset() { return byte_offset_of(Klass, _java_mirror); }
451 static ByteSize class_loader_data_offset() { return byte_offset_of(Klass, _class_loader_data); }
452 static ByteSize layout_helper_offset() { return byte_offset_of(Klass, _layout_helper); }
453 static ByteSize secondary_supers_bitmap_offset()
454 { return byte_offset_of(Klass, _secondary_supers_bitmap); }
455 static ByteSize hash_slot_offset() { return byte_offset_of(Klass, _hash_slot); }
456 static ByteSize misc_flags_offset() { return byte_offset_of(Klass, _misc_flags._flags); }
457
458 // Unpacking layout_helper:
459 static const int _lh_neutral_value = 0; // neutral non-array non-instance value
460 static const int _lh_instance_slow_path_bit = 0x01;
461 static const int _lh_log2_element_size_shift = BitsPerByte*0;
462 static const int _lh_log2_element_size_mask = BitsPerLong-1;
463 static const int _lh_element_type_shift = BitsPerByte*1;
464 static const int _lh_element_type_mask = right_n_bits<int>(BitsPerByte); // shifted mask
465 static const int _lh_header_size_shift = BitsPerByte*2;
466 static const int _lh_header_size_mask = right_n_bits<int>(BitsPerByte); // shifted mask
467 static const int _lh_array_tag_bits = 2;
468 static const int _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits;
469 static const int _lh_array_tag_obj_value = ~0x01; // 0x80000000 >> 30
470
471 static const unsigned int _lh_array_tag_type_value = 0Xffffffff; // ~0x00, // 0xC0000000 >> 30
472
473 static int layout_helper_size_in_bytes(jint lh) {
474 assert(lh > (jint)_lh_neutral_value, "must be instance");
475 return (int) lh & ~_lh_instance_slow_path_bit;
476 }
477 static bool layout_helper_needs_slow_path(jint lh) {
478 assert(lh > (jint)_lh_neutral_value, "must be instance");
479 return (lh & _lh_instance_slow_path_bit) != 0;
480 }
481 static bool layout_helper_is_instance(jint lh) {
482 return (jint)lh > (jint)_lh_neutral_value;
483 }
484 static bool layout_helper_is_array(jint lh) {
485 return (jint)lh < (jint)_lh_neutral_value;
486 }
487 static bool layout_helper_is_typeArray(jint lh) {
488 // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
489 return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
490 }
491 static bool layout_helper_is_objArray(jint lh) {
492 // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
493 return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
494 }
495 static int layout_helper_header_size(jint lh) {
496 assert(lh < (jint)_lh_neutral_value, "must be array");
497 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
498 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
499 return hsize;
500 }
501 static BasicType layout_helper_element_type(jint lh) {
502 assert(lh < (jint)_lh_neutral_value, "must be array");
503 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
504 assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
505 return (BasicType) btvalue;
506 }
507
508 // Return a value containing a single set bit that is in the bitset difference between the
509 // layout helpers for array-of-boolean and array-of-byte.
510 static int layout_helper_boolean_diffbit() {
511 uint zlh = static_cast<uint>(array_layout_helper(T_BOOLEAN));
512 uint blh = static_cast<uint>(array_layout_helper(T_BYTE));
513 // get all the bits that are set in zlh and clear in blh
514 uint candidates = (zlh & ~blh);
515 assert(candidates != 0, "must be"); // must be some if there is a solution.
516 // Use well known bit hack to isolate the low bit of candidates.
517 uint result = candidates & (-candidates);
518 assert(is_power_of_2(result), "must be power of 2");
519 assert((result & zlh) != 0, "must be set in alh of T_BOOLEAN");
520 assert((result & blh) == 0, "must be clear in alh of T_BYTE");
521 return static_cast<int>(result);
522 }
523
524 static int layout_helper_log2_element_size(jint lh) {
525 assert(lh < (jint)_lh_neutral_value, "must be array");
526 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
527 assert(l2esz <= LogBytesPerLong,
528 "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh);
529 return l2esz;
530 }
531 static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
532 return (tag << _lh_array_tag_shift)
533 | (hsize << _lh_header_size_shift)
534 | ((int)etype << _lh_element_type_shift)
535 | (log2_esize << _lh_log2_element_size_shift);
536 }
537 static jint instance_layout_helper(jint size, bool slow_path_flag) {
538 return (size << LogBytesPerWord)
539 | (slow_path_flag ? _lh_instance_slow_path_bit : 0);
540 }
541 static int layout_helper_to_size_helper(jint lh) {
542 assert(lh > (jint)_lh_neutral_value, "must be instance");
543 // Note that the following expression discards _lh_instance_slow_path_bit.
544 return lh >> LogBytesPerWord;
545 }
546 // Out-of-line version computes everything based on the etype:
547 static jint array_layout_helper(BasicType etype);
548
549 // What is the maximum number of primary superclasses any klass can have?
550 static juint primary_super_limit() { return _primary_super_limit; }
551
552 // vtables
653 const char* external_name() const;
654 // Returns the name for a class (Resource allocated) as the class
655 // would appear in a signature.
656 // For arrays, this returns the name of the element with a leading '['.
657 // For classes, this returns the name with a leading 'L' and a trailing ';'
658 // and the package separators as '/'.
659 virtual const char* signature_name() const;
660
661 const char* joint_in_module_of_loader(const Klass* class2, bool include_parent_loader = false) const;
662 const char* class_in_module_of_loader(bool use_are = false, bool include_parent_loader = false) const;
663
664 // Returns "interface", "abstract class" or "class".
665 const char* external_kind() const;
666
667 // type testing operations
668 #ifdef ASSERT
669 protected:
670 virtual bool is_instance_klass_slow() const { return false; }
671 virtual bool is_array_klass_slow() const { return false; }
672 virtual bool is_objArray_klass_slow() const { return false; }
673 virtual bool is_typeArray_klass_slow() const { return false; }
674 #endif // ASSERT
675 public:
676
677 // Fast non-virtual versions
678 #ifndef ASSERT
679 #define assert_same_query(xval, xcheck) xval
680 #else
681 private:
682 static bool assert_same_query(bool xval, bool xslow) {
683 assert(xval == xslow, "slow and fast queries agree");
684 return xval;
685 }
686 public:
687 #endif
688
689 bool is_instance_klass() const { return assert_same_query(_kind <= InstanceStackChunkKlassKind, is_instance_klass_slow()); }
690 // Other is anything that is not one of the more specialized kinds of InstanceKlass.
691 bool is_other_instance_klass() const { return _kind == InstanceKlassKind; }
692 bool is_reference_instance_klass() const { return _kind == InstanceRefKlassKind; }
693 bool is_mirror_instance_klass() const { return _kind == InstanceMirrorKlassKind; }
694 bool is_class_loader_instance_klass() const { return _kind == InstanceClassLoaderKlassKind; }
695 bool is_array_klass() const { return assert_same_query( _kind >= TypeArrayKlassKind, is_array_klass_slow()); }
696 bool is_stack_chunk_instance_klass() const { return _kind == InstanceStackChunkKlassKind; }
697 bool is_objArray_klass() const { return assert_same_query( _kind == ObjArrayKlassKind, is_objArray_klass_slow()); }
698 bool is_typeArray_klass() const { return assert_same_query( _kind == TypeArrayKlassKind, is_typeArray_klass_slow()); }
699 #undef assert_same_query
700
701
702 virtual bool is_interface() const { return false; }
703 virtual bool is_abstract() const { return false; }
704
705 bool has_finalizer() const { return _misc_flags.has_finalizer(); }
706 void set_has_finalizer() { _misc_flags.set_has_finalizer(true); }
707 bool is_hidden() const { return _misc_flags.is_hidden_class(); }
708 void set_is_hidden() { _misc_flags.set_is_hidden_class(true); }
709 bool is_value_based() const { return _misc_flags.is_value_based_class(); }
710 void set_is_value_based() { _misc_flags.set_is_value_based_class(true); }
711
712 klass_flags_t misc_flags() const { return _misc_flags.value(); }
713
714 inline bool is_non_strong_hidden() const;
715
716 bool is_cloneable() const;
717 void set_is_cloneable_fast() { _misc_flags.set_is_cloneable_fast(true); }
718
719 inline markWord prototype_header() const;
720 inline void set_prototype_header(markWord header);
721 static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); }
722
723 JFR_ONLY(DEFINE_TRACE_ID_METHODS;)
724
725 void metaspace_pointers_do(MetaspaceClosure* iter) override;
726 MetaspaceObj::Type type() const override { return ClassType; }
727
728 inline bool is_loader_alive() const;
729 inline bool is_loader_present_and_alive() const;
730
731 Klass* clean_subklass(bool log = false);
732
733 // Clean out unnecessary weak klass links from the whole klass hierarchy.
734 static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true);
735 // Clean out unnecessary weak klass links from the given InstanceKlass.
736 static void clean_weak_instanceklass_links(InstanceKlass* ik);
737
738 // Return self, except for abstract classes with exactly 1
739 // implementor. Then return the 1 concrete implementation.
740 Klass *up_cast_abstract();
741
758 virtual jint jvmti_class_status() const;
759
760 // Printing
761 void print_on(outputStream* st) const override;
762
763 virtual void oop_print_value_on(oop obj, outputStream* st);
764 virtual void oop_print_on (oop obj, outputStream* st);
765
766 void print_secondary_supers_on(outputStream* st) const;
767
768 // Verification
769 virtual void verify_on(outputStream* st);
770 void verify() { verify_on(tty); }
771
772 #ifndef PRODUCT
773 bool verify_vtable_index(int index);
774 #endif
775
776 virtual void oop_verify_on(oop obj, outputStream* st);
777
778 // for error reporting
779 static bool is_valid(Klass* k);
780
781 static void on_secondary_supers_verification_failure(Klass* super, Klass* sub, bool linear_result, bool table_result, const char* msg);
782 };
783
784 #endif // SHARE_OOPS_KLASS_HPP
|
35 #include "jfr/support/jfrTraceIdExtension.hpp"
36 #endif
37
38 //
39 // A Klass provides:
40 // 1: language level class object (method dictionary etc.)
41 // 2: provide vm dispatch behavior for the object
42 // Both functions are combined into one C++ class.
43
44 // One reason for the oop/klass dichotomy in the implementation is
45 // that we don't want a C++ vtbl pointer in every object. Thus,
46 // normal oops don't have any virtual functions. Instead, they
47 // forward all "virtual" functions to their klass, which does have
48 // a vtbl and does the C++ dispatch depending on the object's
49 // actual type. (See oop.inline.hpp for some of the forwarding code.)
50 // ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"!
51
52 // Forward declarations.
53 template <class T> class Array;
54 template <class T> class GrowableArray;
55 class ArrayDescription;
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 public:
67 // Klass Kinds for all subclasses of Klass
68 enum KlassKind : u2
69 {
70 InstanceKlassKind,
71 InlineKlassKind,
72 InstanceRefKlassKind,
73 InstanceMirrorKlassKind,
74 InstanceClassLoaderKlassKind,
75 InstanceStackChunkKlassKind,
76 TypeArrayKlassKind,
77 ObjArrayKlassKind,
78 RefArrayKlassKind,
79 FlatArrayKlassKind,
80 UnknownKlassKind
81 };
82
83 static const uint KLASS_KIND_COUNT = FlatArrayKlassKind + 1;
84 protected:
85
86 // If you add a new field that points to any metaspace object, you
87 // must add this field to Klass::metaspace_pointers_do().
88
89 // note: put frequently-used fields together at start of klass structure
90 // for better cache behavior (may not make much of a difference but sure won't hurt)
91 enum { _primary_super_limit = 8 };
92
93 // The "layout helper" is a combined descriptor of object layout.
94 // For klasses which are neither instance nor array, the value is zero.
95 //
96 // For instances, layout helper is a positive number, the instance size.
97 // This size is already passed through align_object_size and scaled to bytes.
98 // The low order bit is set if instances of this class cannot be
99 // allocated using the fastpath.
100 //
101 // For arrays, layout helper is a negative number, containing four
102 // distinct bytes, as follows:
103 // MSB:[tag, hsz, ebt, log2(esz)]:LSB
104 // where:
105 // tag is 0x80 if the elements are oops, 0xC0 if non-oops, 0xA0 if value types
106 // hsz is array header size in bytes (i.e., offset of first element)
107 // ebt is the BasicType of the elements
108 // esz is the element size in bytes
109 // This packed word is arranged so as to be quickly unpacked by the
110 // various fast paths that use the various subfields.
111 //
112 // The esz bits can be used directly by a SLL instruction, without masking.
113 //
114 // Note that the array-kind tag looks like 0x00 for instance klasses,
115 // since their length in bytes is always less than 24Mb.
116 //
117 // Final note: This comes first, immediately after C++ vtable,
118 // because it is frequently queried.
119 jint _layout_helper;
120
121 // Klass kind used to resolve the runtime type of the instance.
122 // - Used to implement devirtualized oop closure dispatching.
123 // - Various type checking in the JVM
124 const KlassKind _kind;
125
189 // no further need to call <clinit>
190 _has_aot_safe_initializer = 1 << 7, // has @AOTSafeClassInitializer annotation
191 _is_runtime_setup_required = 1 << 8, // has a runtimeSetup method to be called when
192 // this class is loaded from AOT cache
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 void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw();
213
214 public:
215 int kind() { return _kind; }
216
217 enum class DefaultsLookupMode { find, skip };
218 enum class OverpassLookupMode { find, skip };
219 enum class StaticLookupMode { find, skip };
220 enum class PrivateLookupMode { find, skip };
221
222 bool is_klass() const override { return true; }
223
224 // super() cannot be InstanceKlass* -- Java arrays are covariant, and _super is used
225 // to implement that. NB: the _super of "[Ljava/lang/Integer;" is "[Ljava/lang/Number;"
226 // If this is not what your code expects, you're probably looking for:
227 // - Klass::java_super() - if you have a Klass*
228 // - InstanceKlass::super() - if you have an InstanceKlass* ik, ik->super() returns InstanceKlass*.
229 Klass* super() const { return _super; }
452 static ByteSize primary_supers_offset() { return byte_offset_of(Klass, _primary_supers); }
453 static ByteSize secondary_super_cache_offset() { return byte_offset_of(Klass, _secondary_super_cache); }
454 static ByteSize secondary_supers_offset() { return byte_offset_of(Klass, _secondary_supers); }
455 static ByteSize java_mirror_offset() { return byte_offset_of(Klass, _java_mirror); }
456 static ByteSize class_loader_data_offset() { return byte_offset_of(Klass, _class_loader_data); }
457 static ByteSize layout_helper_offset() { return byte_offset_of(Klass, _layout_helper); }
458 static ByteSize secondary_supers_bitmap_offset()
459 { return byte_offset_of(Klass, _secondary_supers_bitmap); }
460 static ByteSize hash_slot_offset() { return byte_offset_of(Klass, _hash_slot); }
461 static ByteSize misc_flags_offset() { return byte_offset_of(Klass, _misc_flags._flags); }
462
463 // Unpacking layout_helper:
464 static const int _lh_neutral_value = 0; // neutral non-array non-instance value
465 static const int _lh_instance_slow_path_bit = 0x01;
466 static const int _lh_log2_element_size_shift = BitsPerByte*0;
467 static const int _lh_log2_element_size_mask = BitsPerLong-1;
468 static const int _lh_element_type_shift = BitsPerByte*1;
469 static const int _lh_element_type_mask = right_n_bits<int>(BitsPerByte); // shifted mask
470 static const int _lh_header_size_shift = BitsPerByte*2;
471 static const int _lh_header_size_mask = right_n_bits<int>(BitsPerByte); // shifted mask
472 static const int _lh_array_tag_bits = 4;
473 static const int _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits;
474
475 static const unsigned int _lh_array_tag_type_value = 0Xfffffffc;
476 static const unsigned int _lh_array_tag_flat_value = 0Xfffffffa;
477 static const unsigned int _lh_array_tag_ref_value = 0Xfffffff8;
478
479 // null-free array flag bit under the array tag bits, shift one more to get array tag value
480 static const int _lh_null_free_shift = _lh_array_tag_shift - 1;
481 static const int _lh_null_free_mask = 1;
482
483 static const jint _lh_array_tag_flat_value_bit_inplace = (jint) (1 << (_lh_array_tag_shift + 1));
484
485 static int layout_helper_size_in_bytes(jint lh) {
486 assert(lh > (jint)_lh_neutral_value, "must be instance");
487 return (int) lh & ~_lh_instance_slow_path_bit;
488 }
489 static bool layout_helper_needs_slow_path(jint lh) {
490 assert(lh > (jint)_lh_neutral_value, "must be instance");
491 return (lh & _lh_instance_slow_path_bit) != 0;
492 }
493 static bool layout_helper_is_instance(jint lh) {
494 return (jint)lh > (jint)_lh_neutral_value;
495 }
496 static bool layout_helper_is_array(jint lh) {
497 return (jint)lh < (jint)_lh_neutral_value;
498 }
499 static bool layout_helper_is_typeArray(jint lh) {
500 return (juint) _lh_array_tag_type_value == (juint)(lh >> _lh_array_tag_shift);
501 }
502 static bool layout_helper_is_refArray(jint lh) {
503 return (juint)_lh_array_tag_ref_value == (juint)(lh >> _lh_array_tag_shift);
504 }
505 static bool layout_helper_is_flatArray(jint lh) {
506 return (juint)_lh_array_tag_flat_value == (juint)(lh >> _lh_array_tag_shift);
507 }
508 static bool layout_helper_is_null_free(jint lh) {
509 assert(layout_helper_is_flatArray(lh) || layout_helper_is_refArray(lh), "must be array of inline types");
510 return ((lh >> _lh_null_free_shift) & _lh_null_free_mask);
511 }
512 static jint layout_helper_set_null_free(jint lh) {
513 lh |= (_lh_null_free_mask << _lh_null_free_shift);
514 assert(layout_helper_is_null_free(lh), "Bad encoding");
515 return lh;
516 }
517 static int layout_helper_header_size(jint lh) {
518 assert(lh < (jint)_lh_neutral_value, "must be array");
519 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
520 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
521 return hsize;
522 }
523 static BasicType layout_helper_element_type(jint lh) {
524 assert(lh < (jint)_lh_neutral_value, "must be array");
525 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
526 assert((btvalue >= T_BOOLEAN && btvalue <= T_OBJECT) || btvalue == T_FLAT_ELEMENT, "sanity");
527 return (BasicType) btvalue;
528 }
529
530 // Return a value containing a single set bit that is in the bitset difference between the
531 // layout helpers for array-of-boolean and array-of-byte.
532 static int layout_helper_boolean_diffbit() {
533 uint zlh = static_cast<uint>(array_layout_helper(T_BOOLEAN));
534 uint blh = static_cast<uint>(array_layout_helper(T_BYTE));
535 // get all the bits that are set in zlh and clear in blh
536 uint candidates = (zlh & ~blh);
537 assert(candidates != 0, "must be"); // must be some if there is a solution.
538 // Use well known bit hack to isolate the low bit of candidates.
539 uint result = candidates & (-candidates);
540 assert(is_power_of_2(result), "must be power of 2");
541 assert((result & zlh) != 0, "must be set in alh of T_BOOLEAN");
542 assert((result & blh) == 0, "must be clear in alh of T_BYTE");
543 return static_cast<int>(result);
544 }
545
546 static int layout_helper_log2_element_size(jint lh) {
547 assert(lh < (jint)_lh_neutral_value, "must be array");
548 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
549 assert(layout_helper_element_type(lh) == T_FLAT_ELEMENT || l2esz <= LogBytesPerLong,
550 "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh);
551 return l2esz;
552 }
553 static jint array_layout_helper(jint tag, bool null_free, int hsize, BasicType etype, int log2_esize) {
554 return (tag << _lh_array_tag_shift)
555 | ((null_free ? 1 : 0) << _lh_null_free_shift)
556 | (hsize << _lh_header_size_shift)
557 | ((int)etype << _lh_element_type_shift)
558 | (log2_esize << _lh_log2_element_size_shift);
559 }
560 static jint instance_layout_helper(jint size, bool slow_path_flag) {
561 return (size << LogBytesPerWord)
562 | (slow_path_flag ? _lh_instance_slow_path_bit : 0);
563 }
564 static int layout_helper_to_size_helper(jint lh) {
565 assert(lh > (jint)_lh_neutral_value, "must be instance");
566 // Note that the following expression discards _lh_instance_slow_path_bit.
567 return lh >> LogBytesPerWord;
568 }
569 // Out-of-line version computes everything based on the etype:
570 static jint array_layout_helper(BasicType etype);
571
572 // What is the maximum number of primary superclasses any klass can have?
573 static juint primary_super_limit() { return _primary_super_limit; }
574
575 // vtables
676 const char* external_name() const;
677 // Returns the name for a class (Resource allocated) as the class
678 // would appear in a signature.
679 // For arrays, this returns the name of the element with a leading '['.
680 // For classes, this returns the name with a leading 'L' and a trailing ';'
681 // and the package separators as '/'.
682 virtual const char* signature_name() const;
683
684 const char* joint_in_module_of_loader(const Klass* class2, bool include_parent_loader = false) const;
685 const char* class_in_module_of_loader(bool use_are = false, bool include_parent_loader = false) const;
686
687 // Returns "interface", "abstract class" or "class".
688 const char* external_kind() const;
689
690 // type testing operations
691 #ifdef ASSERT
692 protected:
693 virtual bool is_instance_klass_slow() const { return false; }
694 virtual bool is_array_klass_slow() const { return false; }
695 virtual bool is_objArray_klass_slow() const { return false; }
696 virtual bool is_refArray_klass_slow() const { return false; }
697 virtual bool is_typeArray_klass_slow() const { return false; }
698 virtual bool is_flatArray_klass_slow() const { return false; }
699 #endif // ASSERT
700 // current implementation uses this method even in non debug builds
701 virtual bool is_inline_klass_slow() const { return false; }
702 public:
703
704 // Fast non-virtual versions
705 #ifndef ASSERT
706 #define assert_same_query(xval, xcheck) xval
707 #else
708 private:
709 static bool assert_same_query(bool xval, bool xslow) {
710 assert(xval == xslow, "slow and fast queries agree");
711 return xval;
712 }
713 public:
714 #endif
715
716 bool is_instance_klass() const { return assert_same_query(_kind <= InstanceStackChunkKlassKind, is_instance_klass_slow()); }
717 bool is_inline_klass() const { return assert_same_query(_kind == InlineKlassKind, is_inline_klass_slow()); }
718 bool is_reference_instance_klass() const { return _kind == InstanceRefKlassKind; }
719 bool is_mirror_instance_klass() const { return _kind == InstanceMirrorKlassKind; }
720 bool is_class_loader_instance_klass() const { return _kind == InstanceClassLoaderKlassKind; }
721 bool is_array_klass() const { return assert_same_query( _kind >= TypeArrayKlassKind, is_array_klass_slow()); }
722 bool is_stack_chunk_instance_klass() const { return _kind == InstanceStackChunkKlassKind; }
723 bool is_flatArray_klass() const { return assert_same_query( _kind == FlatArrayKlassKind, is_flatArray_klass_slow()); }
724 bool is_objArray_klass() const { return assert_same_query( _kind == ObjArrayKlassKind || _kind == RefArrayKlassKind || _kind == FlatArrayKlassKind, is_objArray_klass_slow()); }
725 bool is_refArray_klass() const { return assert_same_query( _kind == RefArrayKlassKind, is_refArray_klass_slow()); }
726 bool is_typeArray_klass() const { return assert_same_query( _kind == TypeArrayKlassKind, is_typeArray_klass_slow()); }
727 bool is_refined_objArray_klass() const { return is_refArray_klass() || is_flatArray_klass(); }
728 bool is_unrefined_objArray_klass() const { return _kind == ObjArrayKlassKind; }
729 #undef assert_same_query
730
731 inline bool is_null_free_array_klass() const { return !is_typeArray_klass() && layout_helper_is_null_free(layout_helper()); }
732
733 virtual bool is_interface() const { return false; }
734 virtual bool is_abstract() const { return false; }
735 virtual bool is_identity_class() const { return false; }
736
737 bool has_finalizer() const { return _misc_flags.has_finalizer(); }
738 void set_has_finalizer() { _misc_flags.set_has_finalizer(true); }
739 bool is_hidden() const { return _misc_flags.is_hidden_class(); }
740 void set_is_hidden() { _misc_flags.set_is_hidden_class(true); }
741 bool is_value_based() const { return _misc_flags.is_value_based_class(); }
742 void set_is_value_based() { _misc_flags.set_is_value_based_class(true); }
743
744 klass_flags_t misc_flags() const { return _misc_flags.value(); }
745
746 inline bool is_non_strong_hidden() const;
747
748 bool is_cloneable() const;
749 void set_is_cloneable_fast() { _misc_flags.set_is_cloneable_fast(true); }
750
751 static inline markWord make_prototype_header(const Klass* kls, markWord prototype = markWord::prototype());
752 inline markWord prototype_header() const;
753 inline void set_prototype_header(markWord header);
754 static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); }
755 inline void set_prototype_header_klass(narrowKlass klass);
756
757 JFR_ONLY(DEFINE_TRACE_ID_METHODS;)
758
759 void metaspace_pointers_do(MetaspaceClosure* iter) override;
760 MetaspaceObj::Type type() const override { return ClassType; }
761
762 inline bool is_loader_alive() const;
763 inline bool is_loader_present_and_alive() const;
764
765 Klass* clean_subklass(bool log = false);
766
767 // Clean out unnecessary weak klass links from the whole klass hierarchy.
768 static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true);
769 // Clean out unnecessary weak klass links from the given InstanceKlass.
770 static void clean_weak_instanceklass_links(InstanceKlass* ik);
771
772 // Return self, except for abstract classes with exactly 1
773 // implementor. Then return the 1 concrete implementation.
774 Klass *up_cast_abstract();
775
792 virtual jint jvmti_class_status() const;
793
794 // Printing
795 void print_on(outputStream* st) const override;
796
797 virtual void oop_print_value_on(oop obj, outputStream* st);
798 virtual void oop_print_on (oop obj, outputStream* st);
799
800 void print_secondary_supers_on(outputStream* st) const;
801
802 // Verification
803 virtual void verify_on(outputStream* st);
804 void verify() { verify_on(tty); }
805
806 #ifndef PRODUCT
807 bool verify_vtable_index(int index);
808 #endif
809
810 virtual void oop_verify_on(oop obj, outputStream* st);
811
812 void validate_array_description(const ArrayDescription& ad) NOT_DEBUG_RETURN;
813
814 // for error reporting
815 static bool is_valid(Klass* k);
816
817 static void on_secondary_supers_verification_failure(Klass* super, Klass* sub, bool linear_result, bool table_result, const char* msg);
818 };
819
820 #endif // SHARE_OOPS_KLASS_HPP
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