1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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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 = int((address)base - (address)klass);
56 _length = length;
57 #ifndef PRODUCT
58 _verify_count = 0;
59 #endif
60 }
61
62 // accessors
63 vtableEntry* table() const { return (vtableEntry*)(address(_klass) + _tableOffset); }
64 Klass* klass() const { return _klass; }
65 int length() const { return _length; }
66 inline Method* method_at(int i) const;
67 inline Method* unchecked_method_at(int i) const;
68
69 // searching; all methods return -1 if not found
70 int index_of_miranda(Symbol* name, Symbol* signature);
71
72 // initialize vtable of a new klass
73 void initialize_vtable(GrowableArray<InstanceKlass*>* supers = nullptr);
74 void initialize_vtable_and_check_constraints(TRAPS);
75
76 // computes vtable length (in words) and the number of miranda methods
77 static void compute_vtable_size_and_num_mirandas(int* vtable_length,
78 int* num_new_mirandas,
79 GrowableArray<Method*>* all_mirandas,
80 const Klass* super,
81 Array<Method*>* methods,
82 AccessFlags class_flags,
83 u2 major_version,
84 Handle classloader,
85 Symbol* classname,
86 Array<InstanceKlass*>* local_interfaces);
87
88 #if INCLUDE_JVMTI
89 // RedefineClasses() API support:
90 // If any entry of this vtable points to any of old_methods,
91 // replace it with the corresponding new_method.
92 // trace_name_printed is set to true if the current call has
93 // printed the klass name so that other routines in the adjust_*
94 // group don't print the klass name.
95 bool adjust_default_method(int vtable_index, Method* old_method, Method* new_method);
96 void adjust_method_entries(bool* trace_name_printed);
97 bool check_no_old_or_obsolete_entries();
98 void dump_vtable();
99 #endif // INCLUDE_JVMTI
100
101 // Debugging code
102 void print() PRODUCT_RETURN;
103 void verify(outputStream* st, bool force = false);
104
105 protected:
106 friend class vtableEntry;
107
108 public:
109 // Transitive overridng rules for class files < JDK1_7 use the older JVMS rules.
110 // Overriding is determined as we create the vtable, so we use the class file version
111 // of the class whose vtable we are calculating.
112 enum { VTABLE_TRANSITIVE_OVERRIDE_VERSION = 51 } ;
113
114 private:
115 void copy_vtable_to(vtableEntry* start);
116 int initialize_from_super(Klass* super);
117 void put_method_at(Method* m, int index);
118 static bool needs_new_vtable_entry(Method* m,
119 const Klass* super,
120 Handle classloader,
121 Symbol* classname,
122 AccessFlags access_flags,
123 u2 major_version);
124
125 bool update_inherited_vtable(Thread* current,
126 const methodHandle& target_method,
127 int super_vtable_len,
128 int default_index,
129 GrowableArray<InstanceKlass*>* supers);
130 InstanceKlass* find_transitive_override(InstanceKlass* initialsuper,
131 const methodHandle& target_method, int vtable_index,
132 Handle target_loader, Symbol* target_classname);
133
134 // support for miranda methods
135 bool is_miranda_entry_at(int i);
136 int fill_in_mirandas(Thread* current, int initialized);
137 static bool is_miranda(Method* m, Array<Method*>* class_methods,
138 Array<Method*>* default_methods, const Klass* super,
139 bool is_interface);
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 bool is_interface);
148 static void get_mirandas(
149 GrowableArray<Method*>* new_mirandas,
150 GrowableArray<Method*>* all_mirandas,
151 const Klass* super,
152 Array<Method*>* class_methods,
153 Array<Method*>* default_methods,
154 Array<InstanceKlass*>* local_interfaces,
155 bool is_interface);
156 void verify_against(outputStream* st, klassVtable* vt, int index);
157 inline InstanceKlass* ik() const;
158 // When loading a class from CDS archive at run time, and no class redefinition
159 // has happened, it is expected that the class's itable/vtables are
160 // laid out exactly the same way as they had been during dump time.
161 // Therefore, in klassVtable::initialize_[iv]table, we do not layout the
162 // tables again. Instead, we only rerun the process to create/check
163 // the class loader constraints. In non-product builds, we add asserts to
164 // guarantee that the table's layout would be the same as at dump time.
165 //
166 // If JVMTI redefines any class, the read-only shared memory are remapped
167 // as read-write. A shared class' vtable/itable are re-initialized and
168 // might have different layout due to class redefinition of the shared class
169 // or its super types.
170 bool is_preinitialized_vtable();
171 };
172
173
174 // private helper class for klassVtable
175 // description of entry points:
176 // destination is interpreted:
177 // from_compiled_code_entry_point -> c2iadapter
178 // from_interpreter_entry_point -> interpreter entry point
179 // destination is compiled:
180 // from_compiled_code_entry_point -> nmethod entry point
181 // from_interpreter_entry_point -> i2cadapter
182 class vtableEntry {
183 friend class VMStructs;
184 friend class JVMCIVMStructs;
185
186 public:
187 // size in words
188 static int size() { return sizeof(vtableEntry) / wordSize; }
189 static int size_in_bytes() { return sizeof(vtableEntry); }
190
191 static ByteSize method_offset() { return byte_offset_of(vtableEntry, _method); }
192 Method* method() const { return _method; }
193 Method** method_addr() { return &_method; }
194
195 private:
196 Method* _method;
197 void set(Method* method) { assert(method != nullptr, "use clear"); _method = method; }
198 void clear() { _method = nullptr; }
199 void print() PRODUCT_RETURN;
200 void verify(klassVtable* vt, outputStream* st);
201
202 friend class klassVtable;
203 };
204
205
206 inline Method* klassVtable::method_at(int i) const {
207 assert(i >= 0 && i < _length, "index out of bounds");
208 assert(table()[i].method() != nullptr, "should not be null");
209 assert(((Metadata*)table()[i].method())->is_method(), "should be method");
210 return table()[i].method();
211 }
212
213 inline Method* klassVtable::unchecked_method_at(int i) const {
214 assert(i >= 0 && i < _length, "index out of bounds");
215 return table()[i].method();
216 }
217
218 // --------------------------------------------------------------------------------
219 class klassItable;
220 class itableMethodEntry;
221
222 class itableOffsetEntry {
223 private:
224 InstanceKlass* _interface;
225 int _offset;
226 public:
227 InstanceKlass* interface_klass() const { return _interface; }
228 InstanceKlass**interface_klass_addr() { return &_interface; }
229 int offset() const { return _offset; }
230
231 static itableMethodEntry* method_entry(Klass* k, int offset) { return (itableMethodEntry*)(((address)k) + offset); }
232 itableMethodEntry* first_method_entry(Klass* k) { return method_entry(k, _offset); }
233
234 void initialize(InstanceKlass* interf, int offset) { _interface = interf; _offset = offset; }
235
236 // Static size and offset accessors
237 static int size() { return sizeof(itableOffsetEntry) / wordSize; } // size in words
238 static ByteSize interface_offset() { return byte_offset_of(itableOffsetEntry, _interface); }
239 static ByteSize offset_offset() { return byte_offset_of(itableOffsetEntry, _offset); }
240
241 friend class klassItable;
242 };
243
244
245 class itableMethodEntry {
246 private:
247 Method* _method;
248
249 public:
250 Method* method() const { return _method; }
251 Method**method_addr() { return &_method; }
252
253 void clear() { _method = nullptr; }
254
255 void initialize(InstanceKlass* klass, Method* method);
256
257 // Static size and offset accessors
258 static int size() { return sizeof(itableMethodEntry) / wordSize; } // size in words
259 static ByteSize method_offset() { return byte_offset_of(itableMethodEntry, _method); }
260
261 friend class klassItable;
262 };
263
264 //
265 // Format of an itable
266 //
267 // ---- offset table ---
268 // Klass* of interface 1 \
269 // offset to vtable from start of oop / offset table entry
270 // ...
271 // Klass* of interface n \
272 // offset to vtable from start of oop / offset table entry
273 // --- vtable for interface 1 ---
274 // Method* \
275 // compiler entry point / method table entry
276 // ...
277 // Method* \
278 // compiler entry point / method table entry
279 // -- vtable for interface 2 ---
280 // ...
281 //
282 class klassItable {
283 private:
284 InstanceKlass* _klass; // my klass
285 int _table_offset; // offset of start of itable data within klass (in words)
286 int _size_offset_table; // size of offset table (in itableOffset entries)
287 int _size_method_table; // size of methodtable (in itableMethodEntry entries)
288
289 void initialize_itable_for_interface(int method_table_offset, InstanceKlass* interf_h,
290 GrowableArray<Method*>* supers, int start_offset);
291 void check_constraints(GrowableArray<Method*>* supers, TRAPS);
292 public:
293 klassItable(InstanceKlass* klass);
294
295 itableOffsetEntry* offset_entry(int i) { assert(0 <= i && i <= _size_offset_table, "index out of bounds");
296 return &((itableOffsetEntry*)vtable_start())[i]; }
297
298 itableMethodEntry* method_entry(int i) { assert(0 <= i && i <= _size_method_table, "index out of bounds");
299 return &((itableMethodEntry*)method_start())[i]; }
300
301 InstanceKlass* klass() const { return _klass; }
302 int table_offset() const { return _table_offset; }
303 int size_offset_table() const { return _size_offset_table; }
304 int size_method_table() const { return _size_method_table; }
305
306 // Initialization
307 void initialize_itable_and_check_constraints(TRAPS);
308 void initialize_itable(GrowableArray<Method*>* supers = nullptr);
309
310 #if INCLUDE_JVMTI
311 // RedefineClasses() API support:
312 // if any entry of this itable points to any of old_methods,
313 // replace it with the corresponding new_method.
314 // trace_name_printed is set to true if the current call has
315 // printed the klass name so that other routines in the adjust_*
316 // group don't print the klass name.
317 void adjust_method_entries(bool* trace_name_printed);
318 bool check_no_old_or_obsolete_entries();
319 void dump_itable();
320 #endif // INCLUDE_JVMTI
321
322 // Setup of itable
323 static int assign_itable_indices_for_interface(InstanceKlass* klass);
324 static int method_count_for_interface(InstanceKlass* klass);
325 static int compute_itable_size(Array<InstanceKlass*>* transitive_interfaces);
326 static void setup_itable_offset_table(InstanceKlass* klass);
327
328 private:
329 intptr_t* vtable_start() const { return ((intptr_t*)_klass) + _table_offset; }
330 intptr_t* method_start() const { return vtable_start() + _size_offset_table * itableOffsetEntry::size(); }
331
332 // Helper methods
333 static int calc_itable_size(int num_interfaces, int num_methods) { return (num_interfaces * itableOffsetEntry::size()) + (num_methods * itableMethodEntry::size()); }
334
335 };
336
337 #endif // SHARE_OOPS_KLASSVTABLE_HPP