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src/hotspot/share/oops/klass.hpp

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   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_VM_OOPS_KLASS_HPP
  26 #define SHARE_VM_OOPS_KLASS_HPP
  27 
  28 #include "classfile/classLoaderData.hpp"
  29 #include "gc/shared/specialized_oop_closures.hpp"
  30 #include "memory/iterator.hpp"
  31 #include "memory/memRegion.hpp"
  32 #include "oops/metadata.hpp"
  33 #include "oops/oop.hpp"
  34 #include "oops/oopHandle.hpp"
  35 #include "utilities/accessFlags.hpp"
  36 #include "utilities/macros.hpp"
  37 #if INCLUDE_JFR
  38 #include "jfr/support/jfrTraceIdExtension.hpp"
  39 #endif
  40 
  41 //
  42 // A Klass provides:
  43 //  1: language level class object (method dictionary etc.)
  44 //  2: provide vm dispatch behavior for the object
  45 // Both functions are combined into one C++ class.
  46 
  47 // One reason for the oop/klass dichotomy in the implementation is
  48 // that we don't want a C++ vtbl pointer in every object.  Thus,
  49 // normal oops don't have any virtual functions.  Instead, they


  86   // For arrays, layout helper is a negative number, containing four
  87   // distinct bytes, as follows:
  88   //    MSB:[tag, hsz, ebt, log2(esz)]:LSB
  89   // where:
  90   //    tag is 0x80 if the elements are oops, 0xC0 if non-oops
  91   //    hsz is array header size in bytes (i.e., offset of first element)
  92   //    ebt is the BasicType of the elements
  93   //    esz is the element size in bytes
  94   // This packed word is arranged so as to be quickly unpacked by the
  95   // various fast paths that use the various subfields.
  96   //
  97   // The esz bits can be used directly by a SLL instruction, without masking.
  98   //
  99   // Note that the array-kind tag looks like 0x00 for instance klasses,
 100   // since their length in bytes is always less than 24Mb.
 101   //
 102   // Final note:  This comes first, immediately after C++ vtable,
 103   // because it is frequently queried.
 104   jint        _layout_helper;
 105 



 106   // The fields _super_check_offset, _secondary_super_cache, _secondary_supers
 107   // and _primary_supers all help make fast subtype checks.  See big discussion
 108   // in doc/server_compiler/checktype.txt
 109   //
 110   // Where to look to observe a supertype (it is &_secondary_super_cache for
 111   // secondary supers, else is &_primary_supers[depth()].
 112   juint       _super_check_offset;
 113 
 114   // Class name.  Instance classes: java/lang/String, etc.  Array classes: [I,
 115   // [Ljava/lang/String;, etc.  Set to zero for all other kinds of classes.
 116   Symbol*     _name;
 117 
 118   // Cache of last observed secondary supertype
 119   Klass*      _secondary_super_cache;
 120   // Array of all secondary supertypes
 121   Array<Klass*>* _secondary_supers;
 122   // Ordered list of all primary supertypes
 123   Klass*      _primary_supers[_primary_super_limit];
 124   // java/lang/Class instance mirroring this class
 125   OopHandle _java_mirror;


 156   // associate this class with the JAR file where it's loaded from during
 157   // dump time. If a class is not loaded from the shared archive, this field is
 158   // -1.
 159   jshort _shared_class_path_index;
 160 
 161 #if INCLUDE_CDS
 162   // Flags of the current shared class.
 163   u2     _shared_class_flags;
 164   enum {
 165     _has_raw_archived_mirror = 1,
 166     _has_signer_and_not_archived = 1 << 2
 167   };
 168 #endif
 169   // The _archived_mirror is set at CDS dump time pointing to the cached mirror
 170   // in the open archive heap region when archiving java object is supported.
 171   CDS_JAVA_HEAP_ONLY(narrowOop _archived_mirror;)
 172 
 173 protected:
 174 
 175   // Constructor
 176   Klass();

 177 
 178   void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw();
 179 
 180  public:


 181   enum DefaultsLookupMode { find_defaults, skip_defaults };
 182   enum OverpassLookupMode { find_overpass, skip_overpass };
 183   enum StaticLookupMode   { find_static,   skip_static };
 184   enum PrivateLookupMode  { find_private,  skip_private };
 185 
 186   bool is_klass() const volatile { return true; }
 187 
 188   // super
 189   Klass* super() const               { return _super; }
 190   void set_super(Klass* k)           { _super = k; }
 191 
 192   // initializes _super link, _primary_supers & _secondary_supers arrays
 193   void initialize_supers(Klass* k, Array<Klass*>* transitive_interfaces, TRAPS);
 194   void initialize_supers_impl1(Klass* k);
 195   void initialize_supers_impl2(Klass* k);
 196 
 197   // klass-specific helper for initializing _secondary_supers
 198   virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots,
 199                                                           Array<Klass*>* transitive_interfaces);
 200 


 636 
 637   // Iff the class loader (or mirror for anonymous classes) is alive the
 638   // Klass is considered alive.  Has already been marked as unloading.
 639   bool is_loader_alive() const { return !class_loader_data()->is_unloading(); }
 640 
 641   static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true);
 642   static void clean_subklass_tree() {
 643     clean_weak_klass_links(/*unloading_occurred*/ true , /* clean_alive_klasses */ false);
 644   }
 645 
 646   // GC specific object visitors
 647   //
 648 #if INCLUDE_PARALLELGC
 649   // Parallel Scavenge
 650   virtual void oop_ps_push_contents(  oop obj, PSPromotionManager* pm)   = 0;
 651   // Parallel Compact
 652   virtual void oop_pc_follow_contents(oop obj, ParCompactionManager* cm) = 0;
 653   virtual void oop_pc_update_pointers(oop obj, ParCompactionManager* cm) = 0;
 654 #endif
 655 
 656   // Iterators specialized to particular subtypes
 657   // of ExtendedOopClosure, to avoid closure virtual calls.
 658 #define Klass_OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix)                                           \
 659   virtual void oop_oop_iterate##nv_suffix(oop obj, OopClosureType* closure) = 0;                        \
 660   /* Iterates "closure" over all the oops in "obj" (of type "this") within "mr". */                     \
 661   virtual void oop_oop_iterate_bounded##nv_suffix(oop obj, OopClosureType* closure, MemRegion mr) = 0;
 662 
 663   ALL_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_DECL)
 664   ALL_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_DECL)
 665 
 666 #if INCLUDE_OOP_OOP_ITERATE_BACKWARDS
 667 #define Klass_OOP_OOP_ITERATE_DECL_BACKWARDS(OopClosureType, nv_suffix)                     \
 668   virtual void oop_oop_iterate_backwards##nv_suffix(oop obj, OopClosureType* closure) = 0;
 669 
 670   ALL_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_DECL_BACKWARDS)
 671   ALL_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_DECL_BACKWARDS)
 672 #endif
 673 
 674   virtual void array_klasses_do(void f(Klass* k)) {}
 675 
 676   // Return self, except for abstract classes with exactly 1
 677   // implementor.  Then return the 1 concrete implementation.
 678   Klass *up_cast_abstract();
 679 
 680   // klass name
 681   Symbol* name() const                   { return _name; }
 682   void set_name(Symbol* n);
 683 
 684  public:
 685   // jvm support
 686   virtual jint compute_modifier_flags(TRAPS) const;
 687 
 688   // JVMTI support
 689   virtual jint jvmti_class_status() const;
 690 
 691   // Printing
 692   virtual void print_on(outputStream* st) const;
 693 


 701   void verify() { verify_on(tty); }
 702 
 703 #ifndef PRODUCT
 704   bool verify_vtable_index(int index);
 705   bool verify_itable_index(int index);
 706 #endif
 707 
 708   virtual void oop_verify_on(oop obj, outputStream* st);
 709 
 710   static bool is_null(narrowKlass obj);
 711   static bool is_null(Klass* obj);
 712 
 713   // klass encoding for klass pointer in objects.
 714   static narrowKlass encode_klass_not_null(Klass* v);
 715   static narrowKlass encode_klass(Klass* v);
 716 
 717   static Klass* decode_klass_not_null(narrowKlass v);
 718   static Klass* decode_klass(narrowKlass v);
 719 };
 720 
 721 // Helper to convert the oop iterate macro suffixes into bool values that can be used by template functions.
 722 #define nvs_nv_to_bool true
 723 #define nvs_v_to_bool  false
 724 #define nvs_to_bool(nv_suffix) nvs##nv_suffix##_to_bool
 725 
 726 // Oop iteration macros for declarations.
 727 // Used to generate declarations in the *Klass header files.
 728 
 729 #define OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix)                                    \
 730   void oop_oop_iterate##nv_suffix(oop obj, OopClosureType* closure);                        \
 731   void oop_oop_iterate_bounded##nv_suffix(oop obj, OopClosureType* closure, MemRegion mr);
 732 
 733 #if INCLUDE_OOP_OOP_ITERATE_BACKWARDS
 734 #define OOP_OOP_ITERATE_DECL_BACKWARDS(OopClosureType, nv_suffix)               \
 735   void oop_oop_iterate_backwards##nv_suffix(oop obj, OopClosureType* closure);
 736 #endif
 737 
 738 
 739 // Oop iteration macros for definitions.
 740 // Used to generate definitions in the *Klass.inline.hpp files.
 741 
 742 #define OOP_OOP_ITERATE_DEFN(KlassType, OopClosureType, nv_suffix)              \
 743 void KlassType::oop_oop_iterate##nv_suffix(oop obj, OopClosureType* closure) {  \
 744   oop_oop_iterate<nvs_to_bool(nv_suffix)>(obj, closure);                        \
 745 }
 746 
 747 #if INCLUDE_OOP_OOP_ITERATE_BACKWARDS
 748 #define OOP_OOP_ITERATE_DEFN_BACKWARDS(KlassType, OopClosureType, nv_suffix)              \
 749 void KlassType::oop_oop_iterate_backwards##nv_suffix(oop obj, OopClosureType* closure) {  \
 750   oop_oop_iterate_reverse<nvs_to_bool(nv_suffix)>(obj, closure);                          \
 751 }
 752 #else
 753 #define OOP_OOP_ITERATE_DEFN_BACKWARDS(KlassType, OopClosureType, nv_suffix)
 754 #endif
 755 
 756 #define OOP_OOP_ITERATE_DEFN_BOUNDED(KlassType, OopClosureType, nv_suffix)                            \
 757 void KlassType::oop_oop_iterate_bounded##nv_suffix(oop obj, OopClosureType* closure, MemRegion mr) {  \
 758   oop_oop_iterate_bounded<nvs_to_bool(nv_suffix)>(obj, closure, mr);                                  \
 759 }
 760 
 761 #endif // SHARE_VM_OOPS_KLASS_HPP


   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_VM_OOPS_KLASS_HPP
  26 #define SHARE_VM_OOPS_KLASS_HPP
  27 
  28 #include "classfile/classLoaderData.hpp"

  29 #include "memory/iterator.hpp"
  30 #include "memory/memRegion.hpp"
  31 #include "oops/metadata.hpp"
  32 #include "oops/oop.hpp"
  33 #include "oops/oopHandle.hpp"
  34 #include "utilities/accessFlags.hpp"
  35 #include "utilities/macros.hpp"
  36 #if INCLUDE_JFR
  37 #include "jfr/support/jfrTraceIdExtension.hpp"
  38 #endif
  39 
  40 //
  41 // A Klass provides:
  42 //  1: language level class object (method dictionary etc.)
  43 //  2: provide vm dispatch behavior for the object
  44 // Both functions are combined into one C++ class.
  45 
  46 // One reason for the oop/klass dichotomy in the implementation is
  47 // that we don't want a C++ vtbl pointer in every object.  Thus,
  48 // normal oops don't have any virtual functions.  Instead, they


  85   // For arrays, layout helper is a negative number, containing four
  86   // distinct bytes, as follows:
  87   //    MSB:[tag, hsz, ebt, log2(esz)]:LSB
  88   // where:
  89   //    tag is 0x80 if the elements are oops, 0xC0 if non-oops
  90   //    hsz is array header size in bytes (i.e., offset of first element)
  91   //    ebt is the BasicType of the elements
  92   //    esz is the element size in bytes
  93   // This packed word is arranged so as to be quickly unpacked by the
  94   // various fast paths that use the various subfields.
  95   //
  96   // The esz bits can be used directly by a SLL instruction, without masking.
  97   //
  98   // Note that the array-kind tag looks like 0x00 for instance klasses,
  99   // since their length in bytes is always less than 24Mb.
 100   //
 101   // Final note:  This comes first, immediately after C++ vtable,
 102   // because it is frequently queried.
 103   jint        _layout_helper;
 104 
 105   // Klass identifier used to implement devirtualized oop closure dispatching.
 106   const int   _id;
 107 
 108   // The fields _super_check_offset, _secondary_super_cache, _secondary_supers
 109   // and _primary_supers all help make fast subtype checks.  See big discussion
 110   // in doc/server_compiler/checktype.txt
 111   //
 112   // Where to look to observe a supertype (it is &_secondary_super_cache for
 113   // secondary supers, else is &_primary_supers[depth()].
 114   juint       _super_check_offset;
 115 
 116   // Class name.  Instance classes: java/lang/String, etc.  Array classes: [I,
 117   // [Ljava/lang/String;, etc.  Set to zero for all other kinds of classes.
 118   Symbol*     _name;
 119 
 120   // Cache of last observed secondary supertype
 121   Klass*      _secondary_super_cache;
 122   // Array of all secondary supertypes
 123   Array<Klass*>* _secondary_supers;
 124   // Ordered list of all primary supertypes
 125   Klass*      _primary_supers[_primary_super_limit];
 126   // java/lang/Class instance mirroring this class
 127   OopHandle _java_mirror;


 158   // associate this class with the JAR file where it's loaded from during
 159   // dump time. If a class is not loaded from the shared archive, this field is
 160   // -1.
 161   jshort _shared_class_path_index;
 162 
 163 #if INCLUDE_CDS
 164   // Flags of the current shared class.
 165   u2     _shared_class_flags;
 166   enum {
 167     _has_raw_archived_mirror = 1,
 168     _has_signer_and_not_archived = 1 << 2
 169   };
 170 #endif
 171   // The _archived_mirror is set at CDS dump time pointing to the cached mirror
 172   // in the open archive heap region when archiving java object is supported.
 173   CDS_JAVA_HEAP_ONLY(narrowOop _archived_mirror;)
 174 
 175 protected:
 176 
 177   // Constructor
 178   Klass(int id);
 179   Klass() : _id(-1) { assert(DumpSharedSpaces || UseSharedSpaces, "only for cds"); }
 180 
 181   void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw();
 182 
 183  public:
 184   int id() { return _id; }
 185 
 186   enum DefaultsLookupMode { find_defaults, skip_defaults };
 187   enum OverpassLookupMode { find_overpass, skip_overpass };
 188   enum StaticLookupMode   { find_static,   skip_static };
 189   enum PrivateLookupMode  { find_private,  skip_private };
 190 
 191   bool is_klass() const volatile { return true; }
 192 
 193   // super
 194   Klass* super() const               { return _super; }
 195   void set_super(Klass* k)           { _super = k; }
 196 
 197   // initializes _super link, _primary_supers & _secondary_supers arrays
 198   void initialize_supers(Klass* k, Array<Klass*>* transitive_interfaces, TRAPS);
 199   void initialize_supers_impl1(Klass* k);
 200   void initialize_supers_impl2(Klass* k);
 201 
 202   // klass-specific helper for initializing _secondary_supers
 203   virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots,
 204                                                           Array<Klass*>* transitive_interfaces);
 205 


 641 
 642   // Iff the class loader (or mirror for anonymous classes) is alive the
 643   // Klass is considered alive.  Has already been marked as unloading.
 644   bool is_loader_alive() const { return !class_loader_data()->is_unloading(); }
 645 
 646   static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true);
 647   static void clean_subklass_tree() {
 648     clean_weak_klass_links(/*unloading_occurred*/ true , /* clean_alive_klasses */ false);
 649   }
 650 
 651   // GC specific object visitors
 652   //
 653 #if INCLUDE_PARALLELGC
 654   // Parallel Scavenge
 655   virtual void oop_ps_push_contents(  oop obj, PSPromotionManager* pm)   = 0;
 656   // Parallel Compact
 657   virtual void oop_pc_follow_contents(oop obj, ParCompactionManager* cm) = 0;
 658   virtual void oop_pc_update_pointers(oop obj, ParCompactionManager* cm) = 0;
 659 #endif
 660 


















 661   virtual void array_klasses_do(void f(Klass* k)) {}
 662 
 663   // Return self, except for abstract classes with exactly 1
 664   // implementor.  Then return the 1 concrete implementation.
 665   Klass *up_cast_abstract();
 666 
 667   // klass name
 668   Symbol* name() const                   { return _name; }
 669   void set_name(Symbol* n);
 670 
 671  public:
 672   // jvm support
 673   virtual jint compute_modifier_flags(TRAPS) const;
 674 
 675   // JVMTI support
 676   virtual jint jvmti_class_status() const;
 677 
 678   // Printing
 679   virtual void print_on(outputStream* st) const;
 680 


 688   void verify() { verify_on(tty); }
 689 
 690 #ifndef PRODUCT
 691   bool verify_vtable_index(int index);
 692   bool verify_itable_index(int index);
 693 #endif
 694 
 695   virtual void oop_verify_on(oop obj, outputStream* st);
 696 
 697   static bool is_null(narrowKlass obj);
 698   static bool is_null(Klass* obj);
 699 
 700   // klass encoding for klass pointer in objects.
 701   static narrowKlass encode_klass_not_null(Klass* v);
 702   static narrowKlass encode_klass(Klass* v);
 703 
 704   static Klass* decode_klass_not_null(narrowKlass v);
 705   static Klass* decode_klass(narrowKlass v);
 706 };
 707 
 708 enum KlassID {
 709   InstanceKlassID,
 710   InstanceRefKlassID,
 711   InstanceMirrorKlassID,
 712   InstanceClassLoaderKlassID,
 713   TypeArrayKlassID,
 714   ObjArrayKlassID
 715 };































 716 
 717 #endif // SHARE_VM_OOPS_KLASS_HPP
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