1 /*
2 * Copyright (c) 1998, 2009, Oracle and/or its affiliates. All rights reserved.
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.
8 *
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 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
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
21 * questions.
22 *
23 */
24
25 // A ConstantPoolCacheEntry describes an individual entry of the constant
26 // pool cache. There's 2 principal kinds of entries: field entries for in-
27 // stance & static field access, and method entries for invokes. Some of
28 // the entry layout is shared and looks as follows:
29 //
30 // bit number |31 0|
31 // bit length |-8--|-8--|---16----|
32 // --------------------------------
33 // _indices [ b2 | b1 | index ]
34 // _f1 [ entry specific ]
35 // _f2 [ entry specific ]
36 // _flags [t|f|vf|v|m|h|unused|field_index] (for field entries)
37 // bit length |4|1|1 |1|1|0|---7--|----16-----]
38 // _flags [t|f|vf|v|m|h|unused|eidx|psze] (for method entries)
39 // bit length |4|1|1 |1|1|1|---7--|-8--|-8--]
40
41 // --------------------------------
42 //
43 // with:
44 // index = original constant pool index
45 // b1 = bytecode 1
46 // b2 = bytecode 2
47 // psze = parameters size (method entries only)
48 // eidx = interpreter entry index (method entries only)
49 // field_index = index into field information in holder instanceKlass
50 // The index max is 0xffff (max number of fields in constant pool)
51 // and is multiplied by (instanceKlass::next_offset) when accessing.
52 // t = TosState (see below)
53 // f = field is marked final (see below)
54 // vf = virtual, final (method entries only : is_vfinal())
55 // v = field is volatile (see below)
56 // m = invokeinterface used for method in class Object (see below)
57 // h = RedefineClasses/Hotswap bit (see below)
58 //
59 // The flags after TosState have the following interpretation:
60 // bit 27: f flag true if field is marked final
61 // bit 26: vf flag true if virtual final method
62 // bit 25: v flag true if field is volatile (only for fields)
63 // bit 24: m flag true if invokeinterface used for method in class Object
64 // bit 23: 0 for fields, 1 for methods
65 //
66 // The flags 31, 30, 29, 28 together build a 4 bit number 0 to 8 with the
67 // following mapping to the TosState states:
68 //
69 // btos: 0
70 // ctos: 1
71 // stos: 2
72 // itos: 3
73 // ltos: 4
74 // ftos: 5
75 // dtos: 6
76 // atos: 7
77 // vtos: 8
78 //
79 // Entry specific: field entries:
80 // _indices = get (b1 section) and put (b2 section) bytecodes, original constant pool index
81 // _f1 = field holder
82 // _f2 = field offset in words
83 // _flags = field type information, original field index in field holder
84 // (field_index section)
85 //
86 // Entry specific: method entries:
87 // _indices = invoke code for f1 (b1 section), invoke code for f2 (b2 section),
88 // original constant pool index
89 // _f1 = method for all but virtual calls, unused by virtual calls
90 // (note: for interface calls, which are essentially virtual,
91 // contains klassOop for the corresponding interface.
92 // for invokedynamic, f1 contains the CallSite object for the invocation
93 // _f2 = method/vtable index for virtual calls only, unused by all other
94 // calls. The vf flag indicates this is a method pointer not an
95 // index.
96 // _flags = field type info (f section),
97 // virtual final entry (vf),
98 // interpreter entry index (eidx section),
99 // parameter size (psze section)
100 //
101 // Note: invokevirtual & invokespecial bytecodes can share the same constant
102 // pool entry and thus the same constant pool cache entry. All invoke
103 // bytecodes but invokevirtual use only _f1 and the corresponding b1
104 // bytecode, while invokevirtual uses only _f2 and the corresponding
105 // b2 bytecode. The value of _flags is shared for both types of entries.
106 //
107 // The fields are volatile so that they are stored in the order written in the
108 // source code. The _indices field with the bytecode must be written last.
109
110 class ConstantPoolCacheEntry VALUE_OBJ_CLASS_SPEC {
111 friend class VMStructs;
112 friend class constantPoolCacheKlass;
113 friend class constantPoolOopDesc; //resolve_constant_at_impl => set_f1
114
115 private:
116 volatile intx _indices; // constant pool index & rewrite bytecodes
117 volatile oop _f1; // entry specific oop field
118 volatile intx _f2; // entry specific int/oop field
119 volatile intx _flags; // flags
120
121
122 #ifdef ASSERT
123 bool same_methodOop(oop cur_f1, oop f1);
124 #endif
125
126 void set_bytecode_1(Bytecodes::Code code);
127 void set_bytecode_2(Bytecodes::Code code);
128 void set_f1(oop f1) {
129 oop existing_f1 = _f1; // read once
130 assert(existing_f1 == NULL || existing_f1 == f1, "illegal field change");
131 oop_store(&_f1, f1);
132 }
133 void set_f2(intx f2) { assert(_f2 == 0 || _f2 == f2, "illegal field change"); _f2 = f2; }
134 int as_flags(TosState state, bool is_final, bool is_vfinal, bool is_volatile,
135 bool is_method_interface, bool is_method);
136 void set_flags(intx flags) { _flags = flags; }
137
138 public:
139 // specific bit values in flag field
140 // Note: the interpreter knows this layout!
141 enum FlagBitValues {
142 hotSwapBit = 23,
143 methodInterface = 24,
144 volatileField = 25,
145 vfinalMethod = 26,
146 finalField = 27
147 };
148
149 enum { field_index_mask = 0xFFFF };
150
151 // start of type bits in flags
152 // Note: the interpreter knows this layout!
153 enum FlagValues {
154 tosBits = 28
155 };
156
157 // Initialization
158 void initialize_entry(int original_index); // initialize primary entry
159 void initialize_secondary_entry(int main_index); // initialize secondary entry
160
161 void set_field( // sets entry to resolved field state
162 Bytecodes::Code get_code, // the bytecode used for reading the field
163 Bytecodes::Code put_code, // the bytecode used for writing the field
164 KlassHandle field_holder, // the object/klass holding the field
165 int orig_field_index, // the original field index in the field holder
166 int field_offset, // the field offset in words in the field holder
167 TosState field_type, // the (machine) field type
168 bool is_final, // the field is final
169 bool is_volatile // the field is volatile
170 );
171
172 void set_method( // sets entry to resolved method entry
173 Bytecodes::Code invoke_code, // the bytecode used for invoking the method
174 methodHandle method, // the method/prototype if any (NULL, otherwise)
175 int vtable_index // the vtable index if any, else negative
176 );
177
178 void set_interface_call(
179 methodHandle method, // Resolved method
180 int index // Method index into interface
181 );
182
183 void set_dynamic_call(
184 Handle call_site, // Resolved java.dyn.CallSite (f1)
185 methodHandle signature_invoker // determines signature information
186 );
187
188 // For JVM_CONSTANT_InvokeDynamic cache entries:
189 void initialize_bootstrap_method_index_in_cache(int bsm_cache_index);
190 int bootstrap_method_index_in_cache();
191
192 void set_parameter_size(int value) {
193 assert(parameter_size() == 0 || parameter_size() == value,
194 "size must not change");
195 // Setting the parameter size by itself is only safe if the
196 // current value of _flags is 0, otherwise another thread may have
197 // updated it and we don't want to overwrite that value. Don't
198 // bother trying to update it once it's nonzero but always make
199 // sure that the final parameter size agrees with what was passed.
200 if (_flags == 0) {
201 Atomic::cmpxchg_ptr((value & 0xFF), &_flags, 0);
202 }
203 guarantee(parameter_size() == value, "size must not change");
204 }
205
206 // Which bytecode number (1 or 2) in the index field is valid for this bytecode?
207 // Returns -1 if neither is valid.
208 static int bytecode_number(Bytecodes::Code code) {
209 switch (code) {
210 case Bytecodes::_getstatic : // fall through
211 case Bytecodes::_getfield : // fall through
212 case Bytecodes::_invokespecial : // fall through
213 case Bytecodes::_invokestatic : // fall through
214 case Bytecodes::_invokedynamic : // fall through
215 case Bytecodes::_invokeinterface : return 1;
216 case Bytecodes::_putstatic : // fall through
217 case Bytecodes::_putfield : // fall through
218 case Bytecodes::_invokevirtual : return 2;
219 default : break;
220 }
221 return -1;
222 }
223
224 // Has this bytecode been resolved? Only valid for invokes and get/put field/static.
225 bool is_resolved(Bytecodes::Code code) const {
226 switch (bytecode_number(code)) {
227 case 1: return (bytecode_1() == code);
228 case 2: return (bytecode_2() == code);
229 }
230 return false; // default: not resolved
231 }
232
233 // Accessors
234 bool is_secondary_entry() const { return (_indices & 0xFFFF) == 0; }
235 int constant_pool_index() const { assert((_indices & 0xFFFF) != 0, "must be main entry");
236 return (_indices & 0xFFFF); }
237 int main_entry_index() const { assert((_indices & 0xFFFF) == 0, "must be secondary entry");
238 return ((uintx)_indices >> 16); }
239 Bytecodes::Code bytecode_1() const { return Bytecodes::cast((_indices >> 16) & 0xFF); }
240 Bytecodes::Code bytecode_2() const { return Bytecodes::cast((_indices >> 24) & 0xFF); }
241 volatile oop f1() const { return _f1; }
242 bool is_f1_null() const { return (oop)_f1 == NULL; } // classifies a CPC entry as unbound
243 intx f2() const { return _f2; }
244 int field_index() const;
245 int parameter_size() const { return _flags & 0xFF; }
246 bool is_vfinal() const { return ((_flags & (1 << vfinalMethod)) == (1 << vfinalMethod)); }
247 bool is_volatile() const { return ((_flags & (1 << volatileField)) == (1 << volatileField)); }
248 bool is_methodInterface() const { return ((_flags & (1 << methodInterface)) == (1 << methodInterface)); }
249 bool is_byte() const { return (((uintx) _flags >> tosBits) == btos); }
250 bool is_char() const { return (((uintx) _flags >> tosBits) == ctos); }
251 bool is_short() const { return (((uintx) _flags >> tosBits) == stos); }
252 bool is_int() const { return (((uintx) _flags >> tosBits) == itos); }
253 bool is_long() const { return (((uintx) _flags >> tosBits) == ltos); }
254 bool is_float() const { return (((uintx) _flags >> tosBits) == ftos); }
255 bool is_double() const { return (((uintx) _flags >> tosBits) == dtos); }
256 bool is_object() const { return (((uintx) _flags >> tosBits) == atos); }
257 TosState flag_state() const { assert( ( (_flags >> tosBits) & 0x0F ) < number_of_states, "Invalid state in as_flags");
258 return (TosState)((_flags >> tosBits) & 0x0F); }
259
260 // Code generation support
261 static WordSize size() { return in_WordSize(sizeof(ConstantPoolCacheEntry) / HeapWordSize); }
262 static ByteSize size_in_bytes() { return in_ByteSize(sizeof(ConstantPoolCacheEntry)); }
263 static ByteSize indices_offset() { return byte_offset_of(ConstantPoolCacheEntry, _indices); }
264 static ByteSize f1_offset() { return byte_offset_of(ConstantPoolCacheEntry, _f1); }
265 static ByteSize f2_offset() { return byte_offset_of(ConstantPoolCacheEntry, _f2); }
266 static ByteSize flags_offset() { return byte_offset_of(ConstantPoolCacheEntry, _flags); }
267
268 // GC Support
269 void oops_do(void f(oop*));
270 void oop_iterate(OopClosure* blk);
271 void oop_iterate_m(OopClosure* blk, MemRegion mr);
272 void follow_contents();
273 void adjust_pointers();
274
275 #ifndef SERIALGC
276 // Parallel Old
277 void follow_contents(ParCompactionManager* cm);
278 #endif // SERIALGC
279
280 void update_pointers();
281 void update_pointers(HeapWord* beg_addr, HeapWord* end_addr);
282
283 // RedefineClasses() API support:
284 // If this constantPoolCacheEntry refers to old_method then update it
285 // to refer to new_method.
286 // trace_name_printed is set to true if the current call has
287 // printed the klass name so that other routines in the adjust_*
288 // group don't print the klass name.
289 bool adjust_method_entry(methodOop old_method, methodOop new_method,
290 bool * trace_name_printed);
291 bool is_interesting_method_entry(klassOop k);
292 bool is_field_entry() const { return (_flags & (1 << hotSwapBit)) == 0; }
293 bool is_method_entry() const { return (_flags & (1 << hotSwapBit)) != 0; }
294
295 // Debugging & Printing
296 void print (outputStream* st, int index) const;
297 void verify(outputStream* st) const;
298
299 static void verify_tosBits() {
300 assert(tosBits == 28, "interpreter now assumes tosBits is 28");
301 }
302 };
303
304
305 // A constant pool cache is a runtime data structure set aside to a constant pool. The cache
306 // holds interpreter runtime information for all field access and invoke bytecodes. The cache
307 // is created and initialized before a class is actively used (i.e., initialized), the indivi-
308 // dual cache entries are filled at resolution (i.e., "link") time (see also: rewriter.*).
309
310 class constantPoolCacheOopDesc: public oopDesc {
311 friend class VMStructs;
312 private:
313 int _length;
314 constantPoolOop _constant_pool; // the corresponding constant pool
315 // If true, safe for concurrent GC processing,
316 // Set unconditionally in constantPoolCacheKlass::allocate()
317 volatile bool _is_conc_safe;
318
319 // Sizing
320 debug_only(friend class ClassVerifier;)
321 int length() const { return _length; }
322 void set_length(int length) { _length = length; }
323
324 static int header_size() { return sizeof(constantPoolCacheOopDesc) / HeapWordSize; }
325 static int object_size(int length) { return align_object_size(header_size() + length * in_words(ConstantPoolCacheEntry::size())); }
326 int object_size() { return object_size(length()); }
327
328 // Helpers
329 constantPoolOop* constant_pool_addr() { return &_constant_pool; }
330 ConstantPoolCacheEntry* base() const { return (ConstantPoolCacheEntry*)((address)this + in_bytes(base_offset())); }
331
332 friend class constantPoolCacheKlass;
333 friend class ConstantPoolCacheEntry;
334
335 public:
336 // Initialization
337 void initialize(intArray& inverse_index_map);
338
339 // Secondary indexes.
340 // They must look completely different from normal indexes.
341 // The main reason is that byte swapping is sometimes done on normal indexes.
342 // Also, some of the CP accessors do different things for secondary indexes.
343 // Finally, it is helpful for debugging to tell the two apart.
344 static bool is_secondary_index(int i) { return (i < 0); }
345 static int decode_secondary_index(int i) { assert(is_secondary_index(i), ""); return ~i; }
346 static int encode_secondary_index(int i) { assert(!is_secondary_index(i), ""); return ~i; }
347
348 // Accessors
349 void set_constant_pool(constantPoolOop pool) { oop_store_without_check((oop*)&_constant_pool, (oop)pool); }
350 constantPoolOop constant_pool() const { return _constant_pool; }
351 // Fetches the entry at the given index.
352 // The entry may be either primary or secondary.
353 // In either case the index must not be encoded or byte-swapped in any way.
354 ConstantPoolCacheEntry* entry_at(int i) const {
355 assert(0 <= i && i < length(), "index out of bounds");
356 return base() + i;
357 }
358 // Fetches the secondary entry referred to by index.
359 // The index may be a secondary index, and must not be byte-swapped.
360 ConstantPoolCacheEntry* secondary_entry_at(int i) const {
361 int raw_index = i;
362 if (is_secondary_index(i)) { // correct these on the fly
363 raw_index = decode_secondary_index(i);
364 }
365 assert(entry_at(raw_index)->is_secondary_entry(), "not a secondary entry");
366 return entry_at(raw_index);
367 }
368 // Given a primary or secondary index, fetch the corresponding primary entry.
369 // Indirect through the secondary entry, if the index is encoded as a secondary index.
370 // The index must not be byte-swapped.
371 ConstantPoolCacheEntry* main_entry_at(int i) const {
372 int primary_index = i;
373 if (is_secondary_index(i)) {
374 // run through an extra level of indirection:
375 int raw_index = decode_secondary_index(i);
376 primary_index = entry_at(raw_index)->main_entry_index();
377 }
378 assert(!entry_at(primary_index)->is_secondary_entry(), "only one level of indirection");
379 return entry_at(primary_index);
380 }
381
382 // GC support
383 // If the _length field has not been set, the size of the
384 // constantPoolCache cannot be correctly calculated.
385 bool is_conc_safe() { return _is_conc_safe; }
386 void set_is_conc_safe(bool v) { _is_conc_safe = v; }
387
388 // Code generation
389 static ByteSize base_offset() { return in_ByteSize(sizeof(constantPoolCacheOopDesc)); }
390 static ByteSize entry_offset(int raw_index) {
391 int index = raw_index;
392 if (is_secondary_index(raw_index))
393 index = decode_secondary_index(raw_index);
394 return (base_offset() + ConstantPoolCacheEntry::size_in_bytes() * index);
395 }
396
397 // RedefineClasses() API support:
398 // If any entry of this constantPoolCache points to any of
399 // old_methods, replace it with the corresponding new_method.
400 // trace_name_printed is set to true if the current call has
401 // printed the klass name so that other routines in the adjust_*
402 // group don't print the klass name.
403 void adjust_method_entries(methodOop* old_methods, methodOop* new_methods,
404 int methods_length, bool * trace_name_printed);
405 };