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