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