1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   6  * under the terms of the GNU General Public License version 2 only, as
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  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).
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  20  * or visit www.oracle.com if you need additional information or have any
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  24 
  25 #ifndef SHARE_VM_OOPS_KLASSVTABLE_HPP
  26 #define SHARE_VM_OOPS_KLASSVTABLE_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "oops/oopsHierarchy.hpp"
  30 #include "runtime/handles.hpp"
  31 #include "utilities/growableArray.hpp"
  32 
  33 // A klassVtable abstracts the variable-length vtable that is embedded in InstanceKlass
  34 // and ArrayKlass.  klassVtable objects are used just as convenient transient accessors to the vtable,
  35 // not to actually hold the vtable data.
  36 // Note: the klassVtable should not be accessed before the class has been verified
  37 // (until that point, the vtable is uninitialized).
  38 
  39 // Currently a klassVtable contains a direct reference to the vtable data, and is therefore
  40 // not preserved across GCs.
  41 
  42 class vtableEntry;
  43 
  44 class klassVtable : public ResourceObj {
  45   Klass*       _klass;            // my klass
  46   int          _tableOffset;      // offset of start of vtable data within klass
  47   int          _length;           // length of vtable (number of entries)
  48 #ifndef PRODUCT
  49   int          _verify_count;     // to make verify faster
  50 #endif
  51 
  52   // Ordering important, so greater_than (>) can be used as an merge operator.
  53   enum AccessType {
  54     acc_private         = 0,
  55     acc_package_private = 1,
  56     acc_publicprotected = 2
  57   };
  58 
  59  public:
  60   klassVtable(Klass* klass, void* base, int length) : _klass(klass) {
  61     _tableOffset = (address)base - (address)klass; _length = length;
  62   }
  63 
  64   // accessors
  65   vtableEntry* table() const      { return (vtableEntry*)(address(_klass) + _tableOffset); }
  66   Klass* klass() const            { return _klass;  }
  67   int length() const              { return _length; }
  68   inline Method* method_at(int i) const;
  69   inline Method* unchecked_method_at(int i) const;
  70   inline Method** adr_method_at(int i) const;
  71 
  72   // searching; all methods return -1 if not found
  73   int index_of(Method* m) const                         { return index_of(m, _length); }
  74   int index_of_miranda(Symbol* name, Symbol* signature);
  75 
  76   void initialize_vtable(bool checkconstraints, TRAPS);   // initialize vtable of a new klass
  77 
  78   // CDS/RedefineClasses support - clear vtables so they can be reinitialized
  79   // at dump time.  Clearing gives us an easy way to tell if the vtable has
  80   // already been reinitialized at dump time (see dump.cpp).  Vtables can
  81   // be initialized at run time by RedefineClasses so dumping the right order
  82   // is necessary.
  83   void clear_vtable();
  84   bool is_initialized();
  85 
  86   // computes vtable length (in words) and the number of miranda methods
  87   static void compute_vtable_size_and_num_mirandas(int* vtable_length,
  88                                                    int* num_new_mirandas,
  89                                                    GrowableArray<Method*>* all_mirandas,
  90                                                    const Klass* super,
  91                                                    Array<Method*>* methods,
  92                                                    AccessFlags class_flags,
  93                                                    u2 major_version,
  94                                                    Handle classloader,
  95                                                    Symbol* classname,
  96                                                    Array<Klass*>* local_interfaces,
  97                                                    TRAPS);
  98 
  99 #if INCLUDE_JVMTI
 100   // RedefineClasses() API support:
 101   // If any entry of this vtable points to any of old_methods,
 102   // replace it with the corresponding new_method.
 103   // trace_name_printed is set to true if the current call has
 104   // printed the klass name so that other routines in the adjust_*
 105   // group don't print the klass name.
 106   bool adjust_default_method(int vtable_index, Method* old_method, Method* new_method);
 107   void adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed);
 108   bool check_no_old_or_obsolete_entries();
 109   void dump_vtable();
 110 #endif // INCLUDE_JVMTI
 111 
 112   // Debugging code
 113   void print()                                              PRODUCT_RETURN;
 114   void verify(outputStream* st, bool force = false);
 115   static void print_statistics()                            PRODUCT_RETURN;
 116 
 117  protected:
 118   friend class vtableEntry;
 119 
 120  public:
 121   // Transitive overridng rules for class files < JDK1_7 use the older JVMS rules.
 122   // Overriding is determined as we create the vtable, so we use the class file version
 123   // of the class whose vtable we are calculating.
 124   enum { VTABLE_TRANSITIVE_OVERRIDE_VERSION = 51 } ;
 125 
 126  private:
 127   void copy_vtable_to(vtableEntry* start);
 128   int  initialize_from_super(Klass* super);
 129   int  index_of(Method* m, int len) const; // same as index_of, but search only up to len
 130   void put_method_at(Method* m, int index);
 131   static bool needs_new_vtable_entry(methodHandle m,
 132                                      const Klass* super,
 133                                      Handle classloader,
 134                                      Symbol* classname,
 135                                      AccessFlags access_flags,
 136                                      u2 major_version,
 137                                      TRAPS);
 138 
 139   bool update_inherited_vtable(InstanceKlass* klass, methodHandle target_method, int super_vtable_len, int default_index, bool checkconstraints, TRAPS);
 140  InstanceKlass* find_transitive_override(InstanceKlass* initialsuper, methodHandle target_method, int vtable_index,
 141                                          Handle target_loader, Symbol* target_classname, Thread* THREAD);
 142 
 143   // support for miranda methods
 144   bool is_miranda_entry_at(int i);
 145   int fill_in_mirandas(int initialized);
 146   static bool is_miranda(Method* m, Array<Method*>* class_methods,
 147                          Array<Method*>* default_methods, const Klass* super);
 148   static void add_new_mirandas_to_lists(
 149       GrowableArray<Method*>* new_mirandas,
 150       GrowableArray<Method*>* all_mirandas,
 151       Array<Method*>* current_interface_methods,
 152       Array<Method*>* class_methods,
 153       Array<Method*>* default_methods,
 154       const Klass* super);
 155   static void get_mirandas(
 156       GrowableArray<Method*>* new_mirandas,
 157       GrowableArray<Method*>* all_mirandas,
 158       const Klass* super,
 159       Array<Method*>* class_methods,
 160       Array<Method*>* default_methods,
 161       Array<Klass*>* local_interfaces);
 162   void verify_against(outputStream* st, klassVtable* vt, int index);
 163   inline InstanceKlass* ik() const;
 164   // When loading a class from CDS archive at run time, and no class redefintion
 165   // has happened, it is expected that the class's itable/vtables are
 166   // laid out exactly the same way as they had been during dump time.
 167   // Therefore, in klassVtable::initialize_[iv]table, we do not layout the
 168   // tables again. Instead, we only rerun the process to create/check
 169   // the class loader constraints. In non-product builds, we add asserts to
 170   // guarantee that the table's layout would be the same as at dump time.
 171   //
 172   // If JVMTI redefines any class, the read-only shared memory are remapped
 173   // as read-write. A shared class' vtable/itable are re-initialized and
 174   // might have different layout due to class redefinition of the shared class
 175   // or its super types.
 176   bool is_preinitialized_vtable();
 177 };
 178 
 179 
 180 // private helper class for klassVtable
 181 // description of entry points:
 182 //    destination is interpreted:
 183 //      from_compiled_code_entry_point -> c2iadapter
 184 //      from_interpreter_entry_point   -> interpreter entry point
 185 //    destination is compiled:
 186 //      from_compiled_code_entry_point -> nmethod entry point
 187 //      from_interpreter_entry_point   -> i2cadapter
 188 class vtableEntry VALUE_OBJ_CLASS_SPEC {
 189   friend class VMStructs;
 190   friend class JVMCIVMStructs;
 191 
 192  public:
 193   // size in words
 194   static int size()          { return sizeof(vtableEntry) / wordSize; }
 195   static int size_in_bytes() { return sizeof(vtableEntry); }
 196 
 197   static int method_offset_in_bytes() { return offset_of(vtableEntry, _method); }
 198   Method* method() const    { return _method; }
 199 
 200  private:
 201   Method* _method;
 202   void set(Method* method)  { assert(method != NULL, "use clear"); _method = method; }
 203   void clear()                { _method = NULL; }
 204   void print()                                        PRODUCT_RETURN;
 205   void verify(klassVtable* vt, outputStream* st);
 206 
 207   friend class klassVtable;
 208 };
 209 
 210 
 211 inline Method* klassVtable::method_at(int i) const {
 212   assert(i >= 0 && i < _length, "index out of bounds");
 213   assert(table()[i].method() != NULL, "should not be null");
 214   assert(((Metadata*)table()[i].method())->is_method(), "should be method");
 215   return table()[i].method();
 216 }
 217 
 218 inline Method* klassVtable::unchecked_method_at(int i) const {
 219   assert(i >= 0 && i < _length, "index out of bounds");
 220   return table()[i].method();
 221 }
 222 
 223 inline Method** klassVtable::adr_method_at(int i) const {
 224   // Allow one past the last entry to be referenced; useful for loop bounds.
 225   assert(i >= 0 && i <= _length, "index out of bounds");
 226   return (Method**)(address(table() + i) + vtableEntry::method_offset_in_bytes());
 227 }
 228 
 229 // --------------------------------------------------------------------------------
 230 class klassItable;
 231 class itableMethodEntry;
 232 
 233 class itableOffsetEntry VALUE_OBJ_CLASS_SPEC {
 234  private:
 235   Klass* _interface;
 236   int      _offset;
 237  public:
 238   Klass* interface_klass() const { return _interface; }
 239   int      offset() const          { return _offset; }
 240 
 241   static itableMethodEntry* method_entry(Klass* k, int offset) { return (itableMethodEntry*)(((address)k) + offset); }
 242   itableMethodEntry* first_method_entry(Klass* k)              { return method_entry(k, _offset); }
 243 
 244   void initialize(Klass* interf, int offset) { _interface = interf; _offset = offset; }
 245 
 246   // Static size and offset accessors
 247   static int size()                       { return sizeof(itableOffsetEntry) / wordSize; }    // size in words
 248   static int interface_offset_in_bytes()  { return offset_of(itableOffsetEntry, _interface); }
 249   static int offset_offset_in_bytes()     { return offset_of(itableOffsetEntry, _offset); }
 250 
 251   friend class klassItable;
 252 };
 253 
 254 
 255 class itableMethodEntry VALUE_OBJ_CLASS_SPEC {
 256  private:
 257   Method* _method;
 258 
 259  public:
 260   Method* method() const { return _method; }
 261 
 262   void clear()             { _method = NULL; }
 263 
 264   void initialize(Method* method);
 265 
 266   // Static size and offset accessors
 267   static int size()                         { return sizeof(itableMethodEntry) / wordSize; }  // size in words
 268   static int method_offset_in_bytes()       { return offset_of(itableMethodEntry, _method); }
 269 
 270   friend class klassItable;
 271 };
 272 
 273 //
 274 // Format of an itable
 275 //
 276 //    ---- offset table ---
 277 //    Klass* of interface 1             \
 278 //    offset to vtable from start of oop  / offset table entry
 279 //    ...
 280 //    Klass* of interface n             \
 281 //    offset to vtable from start of oop  / offset table entry
 282 //    --- vtable for interface 1 ---
 283 //    Method*                             \
 284 //    compiler entry point                / method table entry
 285 //    ...
 286 //    Method*                             \
 287 //    compiler entry point                / method table entry
 288 //    -- vtable for interface 2 ---
 289 //    ...
 290 //
 291 class klassItable : public ResourceObj {
 292  private:
 293   InstanceKlass*       _klass;             // my klass
 294   int                  _table_offset;      // offset of start of itable data within klass (in words)
 295   int                  _size_offset_table; // size of offset table (in itableOffset entries)
 296   int                  _size_method_table; // size of methodtable (in itableMethodEntry entries)
 297 
 298   void initialize_itable_for_interface(int method_table_offset, Klass* interf_h, bool checkconstraints, TRAPS);
 299  public:
 300   klassItable(InstanceKlass* klass);
 301 
 302   itableOffsetEntry* offset_entry(int i) { assert(0 <= i && i <= _size_offset_table, "index out of bounds");
 303                                            return &((itableOffsetEntry*)vtable_start())[i]; }
 304 
 305   itableMethodEntry* method_entry(int i) { assert(0 <= i && i <= _size_method_table, "index out of bounds");
 306                                            return &((itableMethodEntry*)method_start())[i]; }
 307 
 308   int size_offset_table()                { return _size_offset_table; }
 309 
 310   // Initialization
 311   void initialize_itable(bool checkconstraints, TRAPS);
 312 
 313   // Updates
 314   void initialize_with_method(Method* m);
 315 
 316 #if INCLUDE_JVMTI
 317   // RedefineClasses() API support:
 318   // if any entry of this itable points to any of old_methods,
 319   // replace it with the corresponding new_method.
 320   // trace_name_printed is set to true if the current call has
 321   // printed the klass name so that other routines in the adjust_*
 322   // group don't print the klass name.
 323   void adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed);
 324   bool check_no_old_or_obsolete_entries();
 325   void dump_itable();
 326 #endif // INCLUDE_JVMTI
 327 
 328   // Setup of itable
 329   static int assign_itable_indices_for_interface(Klass* klass);
 330   static int method_count_for_interface(Klass* klass);
 331   static int compute_itable_size(Array<Klass*>* transitive_interfaces);
 332   static void setup_itable_offset_table(InstanceKlass* klass);
 333 
 334   // Resolving of method to index
 335   static Method* method_for_itable_index(Klass* klass, int itable_index);
 336 
 337   // Debugging/Statistics
 338   static void print_statistics() PRODUCT_RETURN;
 339  private:
 340   intptr_t* vtable_start() const { return ((intptr_t*)_klass) + _table_offset; }
 341   intptr_t* method_start() const { return vtable_start() + _size_offset_table * itableOffsetEntry::size(); }
 342 
 343   // Helper methods
 344   static int  calc_itable_size(int num_interfaces, int num_methods) { return (num_interfaces * itableOffsetEntry::size()) + (num_methods * itableMethodEntry::size()); }
 345 
 346   // Statistics
 347   NOT_PRODUCT(static int  _total_classes;)   // Total no. of classes with itables
 348   NOT_PRODUCT(static long _total_size;)      // Total no. of bytes used for itables
 349 
 350   static void update_stats(int size) PRODUCT_RETURN NOT_PRODUCT({ _total_classes++; _total_size += size; })
 351 };
 352 
 353 #endif // SHARE_VM_OOPS_KLASSVTABLE_HPP
--- EOF ---