1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   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.
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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   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(
  88       int* vtable_length, int* num_new_mirandas,
  89       GrowableArray<Method*>* all_mirandas, Klass* super,
  90       Array<Method*>* methods, AccessFlags class_flags, Handle classloader,
  91       Symbol* classname, Array<Klass*>* local_interfaces, TRAPS);
  92 
  93 #if INCLUDE_JVMTI
  94   // RedefineClasses() API support:
  95   // If any entry of this vtable points to any of old_methods,
  96   // replace it with the corresponding new_method.
  97   // trace_name_printed is set to true if the current call has
  98   // printed the klass name so that other routines in the adjust_*
  99   // group don't print the klass name.
 100   bool adjust_default_method(int vtable_index, Method* old_method, Method* new_method);
 101   void adjust_method_entries(Method** old_methods, Method** new_methods,
 102                              int methods_length, bool * trace_name_printed);
 103   bool check_no_old_or_obsolete_entries();
 104   void dump_vtable();
 105 #endif // INCLUDE_JVMTI
 106 
 107   // Debugging code
 108   void print()                                              PRODUCT_RETURN;
 109   void verify(outputStream* st, bool force = false);
 110   static void print_statistics()                            PRODUCT_RETURN;
 111 
 112  protected:
 113   friend class vtableEntry;
 114  private:
 115   enum { VTABLE_TRANSITIVE_OVERRIDE_VERSION = 51 } ;
 116   void copy_vtable_to(vtableEntry* start);
 117   int  initialize_from_super(KlassHandle super);
 118   int  index_of(Method* m, int len) const; // same as index_of, but search only up to len
 119   void put_method_at(Method* m, int index);
 120   static bool needs_new_vtable_entry(methodHandle m, Klass* super, Handle classloader, Symbol* classname, AccessFlags access_flags, TRAPS);
 121 
 122   bool update_inherited_vtable(InstanceKlass* klass, methodHandle target_method, int super_vtable_len, int default_index, bool checkconstraints, TRAPS);
 123  InstanceKlass* find_transitive_override(InstanceKlass* initialsuper, methodHandle target_method, int vtable_index,
 124                                          Handle target_loader, Symbol* target_classname, Thread* THREAD);
 125 
 126   // support for miranda methods
 127   bool is_miranda_entry_at(int i);
 128   int fill_in_mirandas(int initialized);
 129   static bool is_miranda(Method* m, Array<Method*>* class_methods,
 130                          Array<Method*>* default_methods, Klass* super);
 131   static void add_new_mirandas_to_lists(
 132       GrowableArray<Method*>* new_mirandas,
 133       GrowableArray<Method*>* all_mirandas,
 134       Array<Method*>* current_interface_methods,
 135       Array<Method*>* class_methods,
 136       Array<Method*>* default_methods,
 137       Klass* super);
 138   static void get_mirandas(
 139       GrowableArray<Method*>* new_mirandas,
 140       GrowableArray<Method*>* all_mirandas, Klass* super,
 141       Array<Method*>* class_methods,
 142       Array<Method*>* default_methods,
 143       Array<Klass*>* local_interfaces);
 144   void verify_against(outputStream* st, klassVtable* vt, int index);
 145   inline InstanceKlass* ik() const;
 146 };
 147 
 148 
 149 // private helper class for klassVtable
 150 // description of entry points:
 151 //    destination is interpreted:
 152 //      from_compiled_code_entry_point -> c2iadapter
 153 //      from_interpreter_entry_point   -> interpreter entry point
 154 //    destination is compiled:
 155 //      from_compiled_code_entry_point -> nmethod entry point
 156 //      from_interpreter_entry_point   -> i2cadapter
 157 class vtableEntry VALUE_OBJ_CLASS_SPEC {
 158   friend class VMStructs;
 159 
 160  public:
 161   // size in words
 162   static int size() {
 163     return sizeof(vtableEntry) / sizeof(HeapWord);
 164   }
 165   static int method_offset_in_bytes() { return offset_of(vtableEntry, _method); }
 166   Method* method() const    { return _method; }
 167 
 168  private:
 169   Method* _method;
 170   void set(Method* method)  { assert(method != NULL, "use clear"); _method = method; }
 171   void clear()                { _method = NULL; }
 172   void print()                                        PRODUCT_RETURN;
 173   void verify(klassVtable* vt, outputStream* st);
 174 
 175   friend class klassVtable;
 176 };
 177 
 178 
 179 inline Method* klassVtable::method_at(int i) const {
 180   assert(i >= 0 && i < _length, "index out of bounds");
 181   assert(table()[i].method() != NULL, "should not be null");
 182   assert(((Metadata*)table()[i].method())->is_method(), "should be method");
 183   return table()[i].method();
 184 }
 185 
 186 inline Method* klassVtable::unchecked_method_at(int i) const {
 187   assert(i >= 0 && i < _length, "index out of bounds");
 188   return table()[i].method();
 189 }
 190 
 191 inline Method** klassVtable::adr_method_at(int i) const {
 192   // Allow one past the last entry to be referenced; useful for loop bounds.
 193   assert(i >= 0 && i <= _length, "index out of bounds");
 194   return (Method**)(address(table() + i) + vtableEntry::method_offset_in_bytes());
 195 }
 196 
 197 // --------------------------------------------------------------------------------
 198 class klassItable;
 199 class itableMethodEntry;
 200 
 201 class itableOffsetEntry VALUE_OBJ_CLASS_SPEC {
 202  private:
 203   Klass* _interface;
 204   int      _offset;
 205  public:
 206   Klass* interface_klass() const { return _interface; }
 207   int      offset() const          { return _offset; }
 208 
 209   static itableMethodEntry* method_entry(Klass* k, int offset) { return (itableMethodEntry*)(((address)k) + offset); }
 210   itableMethodEntry* first_method_entry(Klass* k)              { return method_entry(k, _offset); }
 211 
 212   void initialize(Klass* interf, int offset) { _interface = interf; _offset = offset; }
 213 
 214   // Static size and offset accessors
 215   static int size()                       { return sizeof(itableOffsetEntry) / HeapWordSize; }    // size in words
 216   static int interface_offset_in_bytes()  { return offset_of(itableOffsetEntry, _interface); }
 217   static int offset_offset_in_bytes()     { return offset_of(itableOffsetEntry, _offset); }
 218 
 219   friend class klassItable;
 220 };
 221 
 222 
 223 class itableMethodEntry VALUE_OBJ_CLASS_SPEC {
 224  private:
 225   Method* _method;
 226 
 227  public:
 228   Method* method() const { return _method; }
 229 
 230   void clear()             { _method = NULL; }
 231 
 232   void initialize(Method* method);
 233 
 234   // Static size and offset accessors
 235   static int size()                         { return sizeof(itableMethodEntry) / HeapWordSize; }  // size in words
 236   static int method_offset_in_bytes()       { return offset_of(itableMethodEntry, _method); }
 237 
 238   friend class klassItable;
 239 };
 240 
 241 //
 242 // Format of an itable
 243 //
 244 //    ---- offset table ---
 245 //    Klass* of interface 1             \
 246 //    offset to vtable from start of oop  / offset table entry
 247 //    ...
 248 //    Klass* of interface n             \
 249 //    offset to vtable from start of oop  / offset table entry
 250 //    --- vtable for interface 1 ---
 251 //    Method*                             \
 252 //    compiler entry point                / method table entry
 253 //    ...
 254 //    Method*                             \
 255 //    compiler entry point                / method table entry
 256 //    -- vtable for interface 2 ---
 257 //    ...
 258 //
 259 class klassItable : public ResourceObj {
 260  private:
 261   instanceKlassHandle  _klass;             // my klass
 262   int                  _table_offset;      // offset of start of itable data within klass (in words)
 263   int                  _size_offset_table; // size of offset table (in itableOffset entries)
 264   int                  _size_method_table; // size of methodtable (in itableMethodEntry entries)
 265 
 266   void initialize_itable_for_interface(int method_table_offset, KlassHandle interf_h, bool checkconstraints, TRAPS);
 267  public:
 268   klassItable(instanceKlassHandle klass);
 269 
 270   itableOffsetEntry* offset_entry(int i) { assert(0 <= i && i <= _size_offset_table, "index out of bounds");
 271                                            return &((itableOffsetEntry*)vtable_start())[i]; }
 272 
 273   itableMethodEntry* method_entry(int i) { assert(0 <= i && i <= _size_method_table, "index out of bounds");
 274                                            return &((itableMethodEntry*)method_start())[i]; }
 275 
 276   int size_offset_table()                { return _size_offset_table; }
 277 
 278   // Initialization
 279   void initialize_itable(bool checkconstraints, TRAPS);
 280 
 281   // Updates
 282   void initialize_with_method(Method* m);
 283 
 284 #if INCLUDE_JVMTI
 285   // RedefineClasses() API support:
 286   // if any entry of this itable points to any of old_methods,
 287   // replace it with the corresponding new_method.
 288   // trace_name_printed is set to true if the current call has
 289   // printed the klass name so that other routines in the adjust_*
 290   // group don't print the klass name.
 291   void adjust_method_entries(Method** old_methods, Method** new_methods,
 292                              int methods_length, bool * trace_name_printed);
 293   bool check_no_old_or_obsolete_entries();
 294   void update_throw_illegal_access_entries();
 295   void dump_itable();
 296 #endif // INCLUDE_JVMTI
 297 
 298   // Setup of itable
 299   static int assign_itable_indices_for_interface(Klass* klass);
 300   static int method_count_for_interface(Klass* klass);
 301   static int compute_itable_size(Array<Klass*>* transitive_interfaces);
 302   static void setup_itable_offset_table(instanceKlassHandle klass);
 303 
 304   // Resolving of method to index
 305   static Method* method_for_itable_index(Klass* klass, int itable_index);
 306 
 307   // Debugging/Statistics
 308   static void print_statistics() PRODUCT_RETURN;
 309  private:
 310   intptr_t* vtable_start() const { return ((intptr_t*)_klass()) + _table_offset; }
 311   intptr_t* method_start() const { return vtable_start() + _size_offset_table * itableOffsetEntry::size(); }
 312 
 313   // Helper methods
 314   static int  calc_itable_size(int num_interfaces, int num_methods) { return (num_interfaces * itableOffsetEntry::size()) + (num_methods * itableMethodEntry::size()); }
 315 
 316   // Statistics
 317   NOT_PRODUCT(static int  _total_classes;)   // Total no. of classes with itables
 318   NOT_PRODUCT(static long _total_size;)      // Total no. of bytes used for itables
 319 
 320   static void update_stats(int size) PRODUCT_RETURN NOT_PRODUCT({ _total_classes++; _total_size += size; })
 321 };
 322 
 323 #endif // SHARE_VM_OOPS_KLASSVTABLE_HPP