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
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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 {
45 Klass* _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(Klass* klass, void* base, int length) : _klass(klass) {
61 _tableOffset = (address)base - (address)klass; _length = length;
62 }
63
64 // accessors
65 vtableEntry* table() const { return (vtableEntry*)(address(_klass) + _tableOffset); }
66 Klass* 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(int* vtable_length,
88 int* num_new_mirandas,
89 GrowableArray<Method*>* all_mirandas,
90 const Klass* super,
91 Array<Method*>* methods,
92 AccessFlags class_flags,
93 u2 major_version,
94 Handle classloader,
95 Symbol* classname,
96 Array<Klass*>* local_interfaces,
97 TRAPS);
98
99 #if INCLUDE_JVMTI
100 // RedefineClasses() API support:
101 // If any entry of this vtable points to any of old_methods,
102 // replace it with the corresponding new_method.
103 // trace_name_printed is set to true if the current call has
104 // printed the klass name so that other routines in the adjust_*
105 // group don't print the klass name.
106 bool adjust_default_method(int vtable_index, Method* old_method, Method* new_method);
107 void adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed);
108 bool check_no_old_or_obsolete_entries();
109 void dump_vtable();
110 #endif // INCLUDE_JVMTI
111
112 // Debugging code
113 void print() PRODUCT_RETURN;
114 void verify(outputStream* st, bool force = false);
115 static void print_statistics() PRODUCT_RETURN;
116
117 protected:
118 friend class vtableEntry;
119
120 public:
121 // Transitive overridng rules for class files < JDK1_7 use the older JVMS rules.
122 // Overriding is determined as we create the vtable, so we use the class file version
123 // of the class whose vtable we are calculating.
124 enum { VTABLE_TRANSITIVE_OVERRIDE_VERSION = 51 } ;
125
126 private:
127 void copy_vtable_to(vtableEntry* start);
128 int initialize_from_super(Klass* super);
129 int index_of(Method* m, int len) const; // same as index_of, but search only up to len
130 void put_method_at(Method* m, int index);
131 static bool needs_new_vtable_entry(const methodHandle& m,
132 const Klass* super,
133 Handle classloader,
134 Symbol* classname,
135 AccessFlags access_flags,
136 u2 major_version,
137 TRAPS);
138
139 bool update_inherited_vtable(InstanceKlass* klass, const methodHandle& target_method, int super_vtable_len, int default_index, bool checkconstraints, TRAPS);
140 InstanceKlass* find_transitive_override(InstanceKlass* initialsuper, const methodHandle& target_method, int vtable_index,
141 Handle target_loader, Symbol* target_classname, Thread* THREAD);
142
143 // support for miranda methods
144 bool is_miranda_entry_at(int i);
145 int fill_in_mirandas(int initialized);
146 static bool is_miranda(Method* m, Array<Method*>* class_methods,
147 Array<Method*>* default_methods, const Klass* super,
148 bool is_interface);
149 static void add_new_mirandas_to_lists(
150 GrowableArray<Method*>* new_mirandas,
151 GrowableArray<Method*>* all_mirandas,
152 Array<Method*>* current_interface_methods,
153 Array<Method*>* class_methods,
154 Array<Method*>* default_methods,
155 const Klass* super,
156 bool is_interface);
157 static void get_mirandas(
158 GrowableArray<Method*>* new_mirandas,
159 GrowableArray<Method*>* all_mirandas,
160 const Klass* super,
161 Array<Method*>* class_methods,
162 Array<Method*>* default_methods,
163 Array<Klass*>* local_interfaces,
164 bool is_interface);
165 void verify_against(outputStream* st, klassVtable* vt, int index);
166 inline InstanceKlass* ik() const;
167 // When loading a class from CDS archive at run time, and no class redefintion
168 // has happened, it is expected that the class's itable/vtables are
169 // laid out exactly the same way as they had been during dump time.
170 // Therefore, in klassVtable::initialize_[iv]table, we do not layout the
171 // tables again. Instead, we only rerun the process to create/check
172 // the class loader constraints. In non-product builds, we add asserts to
173 // guarantee that the table's layout would be the same as at dump time.
174 //
175 // If JVMTI redefines any class, the read-only shared memory are remapped
176 // as read-write. A shared class' vtable/itable are re-initialized and
177 // might have different layout due to class redefinition of the shared class
178 // or its super types.
179 bool is_preinitialized_vtable();
180 };
181
182
183 // private helper class for klassVtable
184 // description of entry points:
185 // destination is interpreted:
186 // from_compiled_code_entry_point -> c2iadapter
187 // from_interpreter_entry_point -> interpreter entry point
188 // destination is compiled:
189 // from_compiled_code_entry_point -> nmethod entry point
190 // from_interpreter_entry_point -> i2cadapter
191 class vtableEntry {
192 friend class VMStructs;
193 friend class JVMCIVMStructs;
194
195 public:
196 // size in words
197 static int size() { return sizeof(vtableEntry) / wordSize; }
198 static int size_in_bytes() { return sizeof(vtableEntry); }
199
200 static int method_offset_in_bytes() { return offset_of(vtableEntry, _method); }
201 Method* method() const { return _method; }
202 Method** method_addr() { return &_method; }
203
204 private:
205 Method* _method;
206 void set(Method* method) { assert(method != NULL, "use clear"); _method = method; }
207 void clear() { _method = NULL; }
208 void print() PRODUCT_RETURN;
209 void verify(klassVtable* vt, outputStream* st);
210
211 friend class klassVtable;
212 };
213
214
215 inline Method* klassVtable::method_at(int i) const {
216 assert(i >= 0 && i < _length, "index out of bounds");
217 assert(table()[i].method() != NULL, "should not be null");
218 assert(((Metadata*)table()[i].method())->is_method(), "should be method");
219 return table()[i].method();
220 }
221
222 inline Method* klassVtable::unchecked_method_at(int i) const {
223 assert(i >= 0 && i < _length, "index out of bounds");
224 return table()[i].method();
225 }
226
227 inline Method** klassVtable::adr_method_at(int i) const {
228 // Allow one past the last entry to be referenced; useful for loop bounds.
229 assert(i >= 0 && i <= _length, "index out of bounds");
230 return (Method**)(address(table() + i) + vtableEntry::method_offset_in_bytes());
231 }
232
233 // --------------------------------------------------------------------------------
234 class klassItable;
235 class itableMethodEntry;
236
237 class itableOffsetEntry {
238 private:
239 Klass* _interface;
240 int _offset;
241 public:
242 Klass* interface_klass() const { return _interface; }
243 Klass**interface_klass_addr() { return &_interface; }
244 int offset() const { return _offset; }
245
246 static itableMethodEntry* method_entry(Klass* k, int offset) { return (itableMethodEntry*)(((address)k) + offset); }
247 itableMethodEntry* first_method_entry(Klass* k) { return method_entry(k, _offset); }
248
249 void initialize(Klass* interf, int offset) { _interface = interf; _offset = offset; }
250
251 // Static size and offset accessors
252 static int size() { return sizeof(itableOffsetEntry) / wordSize; } // size in words
253 static int interface_offset_in_bytes() { return offset_of(itableOffsetEntry, _interface); }
254 static int offset_offset_in_bytes() { return offset_of(itableOffsetEntry, _offset); }
255
256 friend class klassItable;
257 };
258
259
260 class itableMethodEntry {
261 private:
262 Method* _method;
263
264 public:
265 Method* method() const { return _method; }
266 Method**method_addr() { return &_method; }
267
268 void clear() { _method = NULL; }
269
270 void initialize(Method* method);
271
272 // Static size and offset accessors
273 static int size() { return sizeof(itableMethodEntry) / wordSize; } // size in words
274 static int method_offset_in_bytes() { return offset_of(itableMethodEntry, _method); }
275
276 friend class klassItable;
277 };
278
279 //
280 // Format of an itable
281 //
282 // ---- offset table ---
283 // Klass* of interface 1 \
284 // offset to vtable from start of oop / offset table entry
285 // ...
286 // Klass* of interface n \
287 // offset to vtable from start of oop / offset table entry
288 // --- vtable for interface 1 ---
289 // Method* \
290 // compiler entry point / method table entry
291 // ...
292 // Method* \
293 // compiler entry point / method table entry
294 // -- vtable for interface 2 ---
295 // ...
296 //
297 class klassItable {
298 private:
299 InstanceKlass* _klass; // my klass
300 int _table_offset; // offset of start of itable data within klass (in words)
301 int _size_offset_table; // size of offset table (in itableOffset entries)
302 int _size_method_table; // size of methodtable (in itableMethodEntry entries)
303
304 void initialize_itable_for_interface(int method_table_offset, Klass* interf_h, bool checkconstraints, TRAPS);
305 public:
306 klassItable(InstanceKlass* klass);
307
308 itableOffsetEntry* offset_entry(int i) { assert(0 <= i && i <= _size_offset_table, "index out of bounds");
309 return &((itableOffsetEntry*)vtable_start())[i]; }
310
311 itableMethodEntry* method_entry(int i) { assert(0 <= i && i <= _size_method_table, "index out of bounds");
312 return &((itableMethodEntry*)method_start())[i]; }
313
314 int size_offset_table() { return _size_offset_table; }
315
316 // Initialization
317 void initialize_itable(bool checkconstraints, TRAPS);
318
319 #if INCLUDE_JVMTI
320 // RedefineClasses() API support:
321 // if any entry of this itable points to any of old_methods,
322 // replace it with the corresponding new_method.
323 // trace_name_printed is set to true if the current call has
324 // printed the klass name so that other routines in the adjust_*
325 // group don't print the klass name.
326 void adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed);
327 bool check_no_old_or_obsolete_entries();
328 void dump_itable();
329 #endif // INCLUDE_JVMTI
330
331 // Setup of itable
332 static int assign_itable_indices_for_interface(Klass* klass);
333 static int method_count_for_interface(Klass* klass);
334 static int compute_itable_size(Array<Klass*>* transitive_interfaces);
335 static void setup_itable_offset_table(InstanceKlass* klass);
336
337 // Resolving of method to index
338 static Method* method_for_itable_index(Klass* klass, int itable_index);
339
340 // Debugging/Statistics
341 static void print_statistics() PRODUCT_RETURN;
342 private:
343 intptr_t* vtable_start() const { return ((intptr_t*)_klass) + _table_offset; }
344 intptr_t* method_start() const { return vtable_start() + _size_offset_table * itableOffsetEntry::size(); }
345
346 // Helper methods
347 static int calc_itable_size(int num_interfaces, int num_methods) { return (num_interfaces * itableOffsetEntry::size()) + (num_methods * itableMethodEntry::size()); }
348
349 // Statistics
350 NOT_PRODUCT(static int _total_classes;) // Total no. of classes with itables
351 NOT_PRODUCT(static long _total_size;) // Total no. of bytes used for itables
352
353 static void update_stats(int size) PRODUCT_RETURN NOT_PRODUCT({ _total_classes++; _total_size += size; })
354 };
355
356 #endif // SHARE_VM_OOPS_KLASSVTABLE_HPP