1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
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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  *
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  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
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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   KlassHandle  _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(KlassHandle h_klass, void* base, int length) : _klass(h_klass) {
  61     _tableOffset = (address)base - (address)h_klass(); _length = length;
  62   }
  63 
  64   // accessors
  65   vtableEntry* table() const      { return (vtableEntry*)(address(_klass()) + _tableOffset); }
  66   KlassHandle 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                                                    Handle classloader,
  94                                                    Symbol* classname,
  95                                                    Array<Klass*>* local_interfaces,
  96                                                    TRAPS);
  97 
  98 #if INCLUDE_JVMTI
  99   // RedefineClasses() API support:
 100   // If any entry of this vtable points to any of old_methods,
 101   // replace it with the corresponding new_method.
 102   // trace_name_printed is set to true if the current call has
 103   // printed the klass name so that other routines in the adjust_*
 104   // group don't print the klass name.
 105   bool adjust_default_method(int vtable_index, Method* old_method, Method* new_method);
 106   void adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed);
 107   bool check_no_old_or_obsolete_entries();
 108   void dump_vtable();
 109 #endif // INCLUDE_JVMTI
 110 
 111   // Debugging code
 112   void print()                                              PRODUCT_RETURN;
 113   void verify(outputStream* st, bool force = false);
 114   static void print_statistics()                            PRODUCT_RETURN;
 115 
 116  protected:
 117   friend class vtableEntry;
 118  private:
 119   enum { VTABLE_TRANSITIVE_OVERRIDE_VERSION = 51 } ;
 120   void copy_vtable_to(vtableEntry* start);
 121   int  initialize_from_super(KlassHandle super);
 122   int  index_of(Method* m, int len) const; // same as index_of, but search only up to len
 123   void put_method_at(Method* m, int index);
 124   static bool needs_new_vtable_entry(methodHandle m,
 125                                      const Klass* super,
 126                                      Handle classloader,
 127                                      Symbol* classname,
 128                                      AccessFlags access_flags,
 129                                      TRAPS);
 130 
 131   bool update_inherited_vtable(InstanceKlass* klass, methodHandle target_method, int super_vtable_len, int default_index, bool checkconstraints, TRAPS);
 132  InstanceKlass* find_transitive_override(InstanceKlass* initialsuper, methodHandle target_method, int vtable_index,
 133                                          Handle target_loader, Symbol* target_classname, Thread* THREAD);
 134 
 135   // support for miranda methods
 136   bool is_miranda_entry_at(int i);
 137   int fill_in_mirandas(int initialized);
 138   static bool is_miranda(Method* m, Array<Method*>* class_methods,
 139                          Array<Method*>* default_methods, const Klass* super);
 140   static void add_new_mirandas_to_lists(
 141       GrowableArray<Method*>* new_mirandas,
 142       GrowableArray<Method*>* all_mirandas,
 143       Array<Method*>* current_interface_methods,
 144       Array<Method*>* class_methods,
 145       Array<Method*>* default_methods,
 146       const Klass* super);
 147   static void get_mirandas(
 148       GrowableArray<Method*>* new_mirandas,
 149       GrowableArray<Method*>* all_mirandas,
 150       const Klass* super,
 151       Array<Method*>* class_methods,
 152       Array<Method*>* default_methods,
 153       Array<Klass*>* local_interfaces);
 154   void verify_against(outputStream* st, klassVtable* vt, int index);
 155   inline InstanceKlass* ik() const;
 156 };
 157 
 158 
 159 // private helper class for klassVtable
 160 // description of entry points:
 161 //    destination is interpreted:
 162 //      from_compiled_code_entry_point -> c2iadapter
 163 //      from_interpreter_entry_point   -> interpreter entry point
 164 //    destination is compiled:
 165 //      from_compiled_code_entry_point -> nmethod entry point
 166 //      from_interpreter_entry_point   -> i2cadapter
 167 class vtableEntry VALUE_OBJ_CLASS_SPEC {
 168   friend class VMStructs;
 169   friend class JVMCIVMStructs;
 170 
 171  public:
 172   // size in words
 173   static int size() {
 174     return sizeof(vtableEntry) / sizeof(HeapWord);
 175   }
 176   static int size_in_bytes() {
 177     return sizeof(vtableEntry);
 178   }
 179   static int method_offset_in_bytes() { return offset_of(vtableEntry, _method); }
 180   Method* method() const    { return _method; }
 181 
 182  private:
 183   Method* _method;
 184   void set(Method* method)  { assert(method != NULL, "use clear"); _method = method; }
 185   void clear()                { _method = NULL; }
 186   void print()                                        PRODUCT_RETURN;
 187   void verify(klassVtable* vt, outputStream* st);
 188 
 189   friend class klassVtable;
 190 };
 191 
 192 
 193 inline Method* klassVtable::method_at(int i) const {
 194   assert(i >= 0 && i < _length, "index out of bounds");
 195   assert(table()[i].method() != NULL, "should not be null");
 196   assert(((Metadata*)table()[i].method())->is_method(), "should be method");
 197   return table()[i].method();
 198 }
 199 
 200 inline Method* klassVtable::unchecked_method_at(int i) const {
 201   assert(i >= 0 && i < _length, "index out of bounds");
 202   return table()[i].method();
 203 }
 204 
 205 inline Method** klassVtable::adr_method_at(int i) const {
 206   // Allow one past the last entry to be referenced; useful for loop bounds.
 207   assert(i >= 0 && i <= _length, "index out of bounds");
 208   return (Method**)(address(table() + i) + vtableEntry::method_offset_in_bytes());
 209 }
 210 
 211 // --------------------------------------------------------------------------------
 212 class klassItable;
 213 class itableMethodEntry;
 214 
 215 class itableOffsetEntry VALUE_OBJ_CLASS_SPEC {
 216  private:
 217   Klass* _interface;
 218   int      _offset;
 219  public:
 220   Klass* interface_klass() const { return _interface; }
 221   int      offset() const          { return _offset; }
 222 
 223   static itableMethodEntry* method_entry(Klass* k, int offset) { return (itableMethodEntry*)(((address)k) + offset); }
 224   itableMethodEntry* first_method_entry(Klass* k)              { return method_entry(k, _offset); }
 225 
 226   void initialize(Klass* interf, int offset) { _interface = interf; _offset = offset; }
 227 
 228   // Static size and offset accessors
 229   static int size()                       { return sizeof(itableOffsetEntry) / HeapWordSize; }    // size in words
 230   static int interface_offset_in_bytes()  { return offset_of(itableOffsetEntry, _interface); }
 231   static int offset_offset_in_bytes()     { return offset_of(itableOffsetEntry, _offset); }
 232 
 233   friend class klassItable;
 234 };
 235 
 236 
 237 class itableMethodEntry VALUE_OBJ_CLASS_SPEC {
 238  private:
 239   Method* _method;
 240 
 241  public:
 242   Method* method() const { return _method; }
 243 
 244   void clear()             { _method = NULL; }
 245 
 246   void initialize(Method* method);
 247 
 248   // Static size and offset accessors
 249   static int size()                         { return sizeof(itableMethodEntry) / HeapWordSize; }  // size in words
 250   static int method_offset_in_bytes()       { return offset_of(itableMethodEntry, _method); }
 251 
 252   friend class klassItable;
 253 };
 254 
 255 //
 256 // Format of an itable
 257 //
 258 //    ---- offset table ---
 259 //    Klass* of interface 1             \
 260 //    offset to vtable from start of oop  / offset table entry
 261 //    ...
 262 //    Klass* of interface n             \
 263 //    offset to vtable from start of oop  / offset table entry
 264 //    --- vtable for interface 1 ---
 265 //    Method*                             \
 266 //    compiler entry point                / method table entry
 267 //    ...
 268 //    Method*                             \
 269 //    compiler entry point                / method table entry
 270 //    -- vtable for interface 2 ---
 271 //    ...
 272 //
 273 class klassItable : public ResourceObj {
 274  private:
 275   instanceKlassHandle  _klass;             // my klass
 276   int                  _table_offset;      // offset of start of itable data within klass (in words)
 277   int                  _size_offset_table; // size of offset table (in itableOffset entries)
 278   int                  _size_method_table; // size of methodtable (in itableMethodEntry entries)
 279 
 280   void initialize_itable_for_interface(int method_table_offset, KlassHandle interf_h, bool checkconstraints, TRAPS);
 281  public:
 282   klassItable(instanceKlassHandle klass);
 283 
 284   itableOffsetEntry* offset_entry(int i) { assert(0 <= i && i <= _size_offset_table, "index out of bounds");
 285                                            return &((itableOffsetEntry*)vtable_start())[i]; }
 286 
 287   itableMethodEntry* method_entry(int i) { assert(0 <= i && i <= _size_method_table, "index out of bounds");
 288                                            return &((itableMethodEntry*)method_start())[i]; }
 289 
 290   int size_offset_table()                { return _size_offset_table; }
 291 
 292   // Initialization
 293   void initialize_itable(bool checkconstraints, TRAPS);
 294 
 295   // Updates
 296   void initialize_with_method(Method* m);
 297 
 298 #if INCLUDE_JVMTI
 299   // RedefineClasses() API support:
 300   // if any entry of this itable points to any of old_methods,
 301   // replace it with the corresponding new_method.
 302   // trace_name_printed is set to true if the current call has
 303   // printed the klass name so that other routines in the adjust_*
 304   // group don't print the klass name.
 305   void adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed);
 306   bool check_no_old_or_obsolete_entries();
 307   void dump_itable();
 308 #endif // INCLUDE_JVMTI
 309 
 310   // Setup of itable
 311   static int assign_itable_indices_for_interface(Klass* klass);
 312   static int method_count_for_interface(Klass* klass);
 313   static int compute_itable_size(Array<Klass*>* transitive_interfaces);
 314   static void setup_itable_offset_table(instanceKlassHandle klass);
 315 
 316   // Resolving of method to index
 317   static Method* method_for_itable_index(Klass* klass, int itable_index);
 318 
 319   // Debugging/Statistics
 320   static void print_statistics() PRODUCT_RETURN;
 321  private:
 322   intptr_t* vtable_start() const { return ((intptr_t*)_klass()) + _table_offset; }
 323   intptr_t* method_start() const { return vtable_start() + _size_offset_table * itableOffsetEntry::size(); }
 324 
 325   // Helper methods
 326   static int  calc_itable_size(int num_interfaces, int num_methods) { return (num_interfaces * itableOffsetEntry::size()) + (num_methods * itableMethodEntry::size()); }
 327 
 328   // Statistics
 329   NOT_PRODUCT(static int  _total_classes;)   // Total no. of classes with itables
 330   NOT_PRODUCT(static long _total_size;)      // Total no. of bytes used for itables
 331 
 332   static void update_stats(int size) PRODUCT_RETURN NOT_PRODUCT({ _total_classes++; _total_size += size; })
 333 };
 334 
 335 #endif // SHARE_VM_OOPS_KLASSVTABLE_HPP