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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
41class vtableEntry;
42
43class 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 // Ordering important, so greater_than (>) can be used as an merge operator.
52 enum AccessType {
53 acc_private = 0,
54 acc_package_private = 1,
55 acc_publicprotected = 2
56 };
57
58 public:
59 klassVtable(Klass* klass, void* base, int length) : _klass(klass) {
60 _tableOffset = (address)base - (address)klass; _length = length;
61 }
62
63 // accessors
64 vtableEntry* table() const { return (vtableEntry*)(address(_klass) + _tableOffset); }
65 Klass* klass() const { return _klass; }
66 int length() const { return _length; }
67 inline Method* method_at(int i) const;
68 inline Method* unchecked_method_at(int i) const;
69 inline Method** adr_method_at(int i) const;
70
71 // searching; all methods return -1 if not found
72 int index_of(Method* m) const { return index_of(m, _length); }
73 int index_of_miranda(Symbol* name, Symbol* signature);
74
75 void initialize_vtable(bool checkconstraints, TRAPS); // initialize vtable of a new klass
76
77 // CDS/RedefineClasses support - clear vtables so they can be reinitialized
78 // at dump time. Clearing gives us an easy way to tell if the vtable has
79 // already been reinitialized at dump time (see dump.cpp). Vtables can
80 // be initialized at run time by RedefineClasses so dumping the right order
81 // is necessary.
82 void clear_vtable();
83 bool is_initialized();
84
85 // computes vtable length (in words) and the number of miranda methods
86 static void compute_vtable_size_and_num_mirandas(int* vtable_length,
87 int* num_new_mirandas,
88 GrowableArray<Method*>* all_mirandas,
89 const Klass* super,
90 Array<Method*>* methods,
91 AccessFlags class_flags,
92 u2 major_version,
93 Handle classloader,
94 Symbol* classname,
95 Array<InstanceKlass*>* 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(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
119 public:
120 // Transitive overridng rules for class files < JDK1_7 use the older JVMS rules.
121 // Overriding is determined as we create the vtable, so we use the class file version
122 // of the class whose vtable we are calculating.
123 enum { VTABLE_TRANSITIVE_OVERRIDE_VERSION = 51 } ;
124
125 private:
126 void copy_vtable_to(vtableEntry* start);
127 int initialize_from_super(Klass* super);
128 int index_of(Method* m, int len) const; // same as index_of, but search only up to len
129 void put_method_at(Method* m, int index);
130 static bool needs_new_vtable_entry(const methodHandle& m,
131 const Klass* super,
132 Handle classloader,
133 Symbol* classname,
134 AccessFlags access_flags,
135 u2 major_version,
136 TRAPS);
137
138 bool update_inherited_vtable(InstanceKlass* klass, const methodHandle& target_method, int super_vtable_len, int default_index, bool checkconstraints, TRAPS);
139 InstanceKlass* find_transitive_override(InstanceKlass* initialsuper, const methodHandle& target_method, int vtable_index,
140 Handle target_loader, Symbol* target_classname, Thread* THREAD);
141
142 // support for miranda methods
143 bool is_miranda_entry_at(int i);
144 int fill_in_mirandas(int initialized, TRAPS);
145 static bool is_miranda(Method* m, Array<Method*>* class_methods,
146 Array<Method*>* default_methods, const Klass* super,
147 bool is_interface);
148 static void add_new_mirandas_to_lists(
149 GrowableArray<Method*>* new_mirandas,
150 GrowableArray<Method*>* all_mirandas,
151 Array<Method*>* current_interface_methods,
152 Array<Method*>* class_methods,
153 Array<Method*>* default_methods,
154 const Klass* super,
155 bool is_interface);
156 static void get_mirandas(
157 GrowableArray<Method*>* new_mirandas,
158 GrowableArray<Method*>* all_mirandas,
159 const Klass* super,
160 Array<Method*>* class_methods,
161 Array<Method*>* default_methods,
162 Array<InstanceKlass*>* local_interfaces,
163 bool is_interface);
164 void verify_against(outputStream* st, klassVtable* vt, int index);
165 inline InstanceKlass* ik() const;
166 // When loading a class from CDS archive at run time, and no class redefintion
167 // has happened, it is expected that the class's itable/vtables are
168 // laid out exactly the same way as they had been during dump time.
169 // Therefore, in klassVtable::initialize_[iv]table, we do not layout the
170 // tables again. Instead, we only rerun the process to create/check
171 // the class loader constraints. In non-product builds, we add asserts to
172 // guarantee that the table's layout would be the same as at dump time.
173 //
174 // If JVMTI redefines any class, the read-only shared memory are remapped
175 // as read-write. A shared class' vtable/itable are re-initialized and
176 // might have different layout due to class redefinition of the shared class
177 // or its super types.
178 bool is_preinitialized_vtable();
179};
180
181
182// private helper class for klassVtable
183// description of entry points:
184// destination is interpreted:
185// from_compiled_code_entry_point -> c2iadapter
186// from_interpreter_entry_point -> interpreter entry point
187// destination is compiled:
188// from_compiled_code_entry_point -> nmethod entry point
189// from_interpreter_entry_point -> i2cadapter
190class vtableEntry {
191 friend class VMStructs;
192 friend class JVMCIVMStructs;
193
194 public:
195 // size in words
196 static int size() { return sizeof(vtableEntry) / wordSize; }
197 static int size_in_bytes() { return sizeof(vtableEntry); }
198
199 static int method_offset_in_bytes() { return offset_of(vtableEntry, _method); }
200 Method* method() const { return _method; }
201 Method** method_addr() { return &_method; }
202
203 private:
204 Method* _method;
205 void set(Method* method) { assert(method != NULL, "use clear"); _method = method; }
206 void clear() { _method = NULL; }
207 void print() PRODUCT_RETURN;
208 void verify(klassVtable* vt, outputStream* st);
209
210 friend class klassVtable;
211};
212
213
214inline Method* klassVtable::method_at(int i) const {
215 assert(i >= 0 && i < _length, "index out of bounds");
216 assert(table()[i].method() != NULL, "should not be null");
217 assert(((Metadata*)table()[i].method())->is_method(), "should be method");
218 return table()[i].method();
219}
220
221inline Method* klassVtable::unchecked_method_at(int i) const {
222 assert(i >= 0 && i < _length, "index out of bounds");
223 return table()[i].method();
224}
225
226inline Method** klassVtable::adr_method_at(int i) const {
227 // Allow one past the last entry to be referenced; useful for loop bounds.
228 assert(i >= 0 && i <= _length, "index out of bounds");
229 return (Method**)(address(table() + i) + vtableEntry::method_offset_in_bytes());
230}
231
232// --------------------------------------------------------------------------------
233class klassItable;
234class itableMethodEntry;
235
236class itableOffsetEntry {
237 private:
238 InstanceKlass* _interface;
239 int _offset;
240 public:
241 InstanceKlass* interface_klass() const { return _interface; }
242 InstanceKlass**interface_klass_addr() { return &_interface; }
243 int offset() const { return _offset; }
244
245 static itableMethodEntry* method_entry(Klass* k, int offset) { return (itableMethodEntry*)(((address)k) + offset); }
246 itableMethodEntry* first_method_entry(Klass* k) { return method_entry(k, _offset); }
247
248 void initialize(InstanceKlass* interf, int offset) { _interface = interf; _offset = offset; }
249
250 // Static size and offset accessors
251 static int size() { return sizeof(itableOffsetEntry) / wordSize; } // size in words
252 static int interface_offset_in_bytes() { return offset_of(itableOffsetEntry, _interface); }
253 static int offset_offset_in_bytes() { return offset_of(itableOffsetEntry, _offset); }
254
255 friend class klassItable;
256};
257
258
259class itableMethodEntry {
260 private:
261 Method* _method;
262
263 public:
264 Method* method() const { return _method; }
265 Method**method_addr() { return &_method; }
266
267 void clear() { _method = NULL; }
268
269 void initialize(Method* method);
270
271 // Static size and offset accessors
272 static int size() { return sizeof(itableMethodEntry) / wordSize; } // size in words
273 static int method_offset_in_bytes() { return offset_of(itableMethodEntry, _method); }
274
275 friend class klassItable;
276};
277
278//
279// Format of an itable
280//
281// ---- offset table ---
282// Klass* of interface 1 \
283// offset to vtable from start of oop / offset table entry
284// ...
285// Klass* of interface n \
286// offset to vtable from start of oop / offset table entry
287// --- vtable for interface 1 ---
288// Method* \
289// compiler entry point / method table entry
290// ...
291// Method* \
292// compiler entry point / method table entry
293// -- vtable for interface 2 ---
294// ...
295//
296class klassItable {
297 private:
298 InstanceKlass* _klass; // my klass
299 int _table_offset; // offset of start of itable data within klass (in words)
300 int _size_offset_table; // size of offset table (in itableOffset entries)
301 int _size_method_table; // size of methodtable (in itableMethodEntry entries)
302
303 void initialize_itable_for_interface(int method_table_offset, InstanceKlass* interf_h, bool checkconstraints, TRAPS);
304 public:
305 klassItable(InstanceKlass* klass);
306
307 itableOffsetEntry* offset_entry(int i) { assert(0 <= i && i <= _size_offset_table, "index out of bounds");
308 return &((itableOffsetEntry*)vtable_start())[i]; }
309
310 itableMethodEntry* method_entry(int i) { assert(0 <= i && i <= _size_method_table, "index out of bounds");
311 return &((itableMethodEntry*)method_start())[i]; }
312
313 int size_offset_table() { return _size_offset_table; }
314
315 // Initialization
316 void initialize_itable(bool checkconstraints, TRAPS);
317
318#if INCLUDE_JVMTI
319 // RedefineClasses() API support:
320 // if any entry of this itable points to any of old_methods,
321 // replace it with the corresponding new_method.
322 // trace_name_printed is set to true if the current call has
323 // printed the klass name so that other routines in the adjust_*
324 // group don't print the klass name.
325 void adjust_method_entries(bool* trace_name_printed);
326 bool check_no_old_or_obsolete_entries();
327 void dump_itable();
328#endif // INCLUDE_JVMTI
329
330 // Setup of itable
331 static int assign_itable_indices_for_interface(InstanceKlass* klass, TRAPS);
332 static int method_count_for_interface(InstanceKlass* klass);
333 static int compute_itable_size(Array<InstanceKlass*>* transitive_interfaces);
334 static void setup_itable_offset_table(InstanceKlass* klass);
335
336 // Resolving of method to index
337 static Method* method_for_itable_index(InstanceKlass* klass, int itable_index);
338
339 // Debugging/Statistics
340 static void print_statistics() PRODUCT_RETURN;
341 private:
342 intptr_t* vtable_start() const { return ((intptr_t*)_klass) + _table_offset; }
343 intptr_t* method_start() const { return vtable_start() + _size_offset_table * itableOffsetEntry::size(); }
344
345 // Helper methods
346 static int calc_itable_size(int num_interfaces, int num_methods) { return (num_interfaces * itableOffsetEntry::size()) + (num_methods * itableMethodEntry::size()); }
347
348 // Statistics
349 NOT_PRODUCT(static int _total_classes;) // Total no. of classes with itables
350 NOT_PRODUCT(static long _total_size;) // Total no. of bytes used for itables
351
352 static void update_stats(int size) PRODUCT_RETURN NOT_PRODUCT({ _total_classes++; _total_size += size; })
353};
354
355#endif // SHARE_OOPS_KLASSVTABLE_HPP
356