1 /*
2 * Copyright (c) 2005, 2012, 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
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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 *
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23 */
24
25 #ifndef SHARE_VM_CODE_DEPENDENCIES_HPP
26 #define SHARE_VM_CODE_DEPENDENCIES_HPP
27
28 #include "ci/ciCallSite.hpp"
29 #include "ci/ciKlass.hpp"
30 #include "ci/ciMethodHandle.hpp"
31 #include "classfile/systemDictionary.hpp"
32 #include "code/compressedStream.hpp"
33 #include "code/nmethod.hpp"
34 #include "utilities/growableArray.hpp"
35 #include "utilities/hashtable.hpp"
36
37 //** Dependencies represent assertions (approximate invariants) within
38 // the runtime system, e.g. class hierarchy changes. An example is an
39 // assertion that a given method is not overridden; another example is
40 // that a type has only one concrete subtype. Compiled code which
41 // relies on such assertions must be discarded if they are overturned
42 // by changes in the runtime system. We can think of these assertions
43 // as approximate invariants, because we expect them to be overturned
44 // very infrequently. We are willing to perform expensive recovery
45 // operations when they are overturned. The benefit, of course, is
46 // performing optimistic optimizations (!) on the object code.
47 //
48 // Changes in the class hierarchy due to dynamic linking or
49 // class evolution can violate dependencies. There is enough
50 // indexing between classes and nmethods to make dependency
51 // checking reasonably efficient.
52
53 class ciEnv;
54 class nmethod;
55 class OopRecorder;
56 class xmlStream;
57 class CompileLog;
58 class DepChange;
59 class KlassDepChange;
60 class CallSiteDepChange;
61 class No_Safepoint_Verifier;
62
63 class Dependencies: public ResourceObj {
64 public:
65 // Note: In the comments on dependency types, most uses of the terms
66 // subtype and supertype are used in a "non-strict" or "inclusive"
67 // sense, and are starred to remind the reader of this fact.
68 // Strict uses of the terms use the word "proper".
69 //
70 // Specifically, every class is its own subtype* and supertype*.
71 // (This trick is easier than continually saying things like "Y is a
72 // subtype of X or X itself".)
73 //
74 // Sometimes we write X > Y to mean X is a proper supertype of Y.
75 // The notation X > {Y, Z} means X has proper subtypes Y, Z.
76 // The notation X.m > Y means that Y inherits m from X, while
77 // X.m > Y.m means Y overrides X.m. A star denotes abstractness,
78 // as *I > A, meaning (abstract) interface I is a super type of A,
79 // or A.*m > B.m, meaning B.m implements abstract method A.m.
80 //
81 // In this module, the terms "subtype" and "supertype" refer to
82 // Java-level reference type conversions, as detected by
83 // "instanceof" and performed by "checkcast" operations. The method
84 // Klass::is_subtype_of tests these relations. Note that "subtype"
85 // is richer than "subclass" (as tested by Klass::is_subclass_of),
86 // since it takes account of relations involving interface and array
87 // types.
88 //
89 // To avoid needless complexity, dependencies involving array types
90 // are not accepted. If you need to make an assertion about an
91 // array type, make the assertion about its corresponding element
92 // types. Any assertion that might change about an array type can
93 // be converted to an assertion about its element type.
94 //
95 // Most dependencies are evaluated over a "context type" CX, which
96 // stands for the set Subtypes(CX) of every Java type that is a subtype*
97 // of CX. When the system loads a new class or interface N, it is
98 // responsible for re-evaluating changed dependencies whose context
99 // type now includes N, that is, all super types of N.
100 //
101 enum DepType {
102 end_marker = 0,
103
104 // An 'evol' dependency simply notes that the contents of the
105 // method were used. If it evolves (is replaced), the nmethod
106 // must be recompiled. No other dependencies are implied.
107 evol_method,
108 FIRST_TYPE = evol_method,
109
110 // A context type CX is a leaf it if has no proper subtype.
111 leaf_type,
112
113 // An abstract class CX has exactly one concrete subtype CC.
114 abstract_with_unique_concrete_subtype,
115
116 // The type CX is purely abstract, with no concrete subtype* at all.
117 abstract_with_no_concrete_subtype,
118
119 // The concrete CX is free of concrete proper subtypes.
120 concrete_with_no_concrete_subtype,
121
122 // Given a method M1 and a context class CX, the set MM(CX, M1) of
123 // "concrete matching methods" in CX of M1 is the set of every
124 // concrete M2 for which it is possible to create an invokevirtual
125 // or invokeinterface call site that can reach either M1 or M2.
126 // That is, M1 and M2 share a name, signature, and vtable index.
127 // We wish to notice when the set MM(CX, M1) is just {M1}, or
128 // perhaps a set of two {M1,M2}, and issue dependencies on this.
129
130 // The set MM(CX, M1) can be computed by starting with any matching
131 // concrete M2 that is inherited into CX, and then walking the
132 // subtypes* of CX looking for concrete definitions.
133
134 // The parameters to this dependency are the method M1 and the
135 // context class CX. M1 must be either inherited in CX or defined
136 // in a subtype* of CX. It asserts that MM(CX, M1) is no greater
137 // than {M1}.
138 unique_concrete_method, // one unique concrete method under CX
139
140 // An "exclusive" assertion concerns two methods or subtypes, and
141 // declares that there are at most two (or perhaps later N>2)
142 // specific items that jointly satisfy the restriction.
143 // We list all items explicitly rather than just giving their
144 // count, for robustness in the face of complex schema changes.
145
146 // A context class CX (which may be either abstract or concrete)
147 // has two exclusive concrete subtypes* C1, C2 if every concrete
148 // subtype* of CX is either C1 or C2. Note that if neither C1 or C2
149 // are equal to CX, then CX itself must be abstract. But it is
150 // also possible (for example) that C1 is CX (a concrete class)
151 // and C2 is a proper subtype of C1.
152 abstract_with_exclusive_concrete_subtypes_2,
153
154 // This dependency asserts that MM(CX, M1) is no greater than {M1,M2}.
155 exclusive_concrete_methods_2,
156
157 // This dependency asserts that no instances of class or it's
158 // subclasses require finalization registration.
159 no_finalizable_subclasses,
160
161 // This dependency asserts when the CallSite.target value changed.
162 call_site_target_value,
163
164 TYPE_LIMIT
165 };
166 enum {
167 LG2_TYPE_LIMIT = 4, // assert(TYPE_LIMIT <= (1<<LG2_TYPE_LIMIT))
168
169 // handy categorizations of dependency types:
170 all_types = ((1 << TYPE_LIMIT) - 1) & ((-1) << FIRST_TYPE),
171
172 non_klass_types = (1 << call_site_target_value),
173 klass_types = all_types & ~non_klass_types,
174
175 non_ctxk_types = (1 << evol_method),
176 implicit_ctxk_types = (1 << call_site_target_value),
177 explicit_ctxk_types = all_types & ~(non_ctxk_types | implicit_ctxk_types),
178
179 max_arg_count = 3, // current maximum number of arguments (incl. ctxk)
180
181 // A "context type" is a class or interface that
182 // provides context for evaluating a dependency.
183 // When present, it is one of the arguments (dep_context_arg).
184 //
185 // If a dependency does not have a context type, there is a
186 // default context, depending on the type of the dependency.
187 // This bit signals that a default context has been compressed away.
188 default_context_type_bit = (1<<LG2_TYPE_LIMIT)
189 };
190
191 static const char* dep_name(DepType dept);
192 static int dep_args(DepType dept);
193
194 static bool is_klass_type( DepType dept) { return dept_in_mask(dept, klass_types ); }
195
196 static bool has_explicit_context_arg(DepType dept) { return dept_in_mask(dept, explicit_ctxk_types); }
197 static bool has_implicit_context_arg(DepType dept) { return dept_in_mask(dept, implicit_ctxk_types); }
198
199 static int dep_context_arg(DepType dept) { return has_explicit_context_arg(dept) ? 0 : -1; }
200 static int dep_implicit_context_arg(DepType dept) { return has_implicit_context_arg(dept) ? 0 : -1; }
201
202 static void check_valid_dependency_type(DepType dept);
203
204 private:
205 // State for writing a new set of dependencies:
206 GrowableArray<int>* _dep_seen; // (seen[h->ident] & (1<<dept))
207 GrowableArray<ciBaseObject*>* _deps[TYPE_LIMIT];
208
209 static const char* _dep_name[TYPE_LIMIT];
210 static int _dep_args[TYPE_LIMIT];
211
212 static bool dept_in_mask(DepType dept, int mask) {
213 return (int)dept >= 0 && dept < TYPE_LIMIT && ((1<<dept) & mask) != 0;
214 }
215
216 bool note_dep_seen(int dept, ciBaseObject* x) {
217 assert(dept < BitsPerInt, "oob");
218 int x_id = x->ident();
219 assert(_dep_seen != NULL, "deps must be writable");
220 int seen = _dep_seen->at_grow(x_id, 0);
221 _dep_seen->at_put(x_id, seen | (1<<dept));
222 // return true if we've already seen dept/x
223 return (seen & (1<<dept)) != 0;
224 }
225
226 bool maybe_merge_ctxk(GrowableArray<ciBaseObject*>* deps,
227 int ctxk_i, ciKlass* ctxk);
228
229 void sort_all_deps();
230 size_t estimate_size_in_bytes();
231
232 // Initialize _deps, etc.
233 void initialize(ciEnv* env);
234
235 // State for making a new set of dependencies:
236 OopRecorder* _oop_recorder;
237
238 // Logging support
239 CompileLog* _log;
240
241 address _content_bytes; // everything but the oop references, encoded
242 size_t _size_in_bytes;
243
244 public:
245 // Make a new empty dependencies set.
246 Dependencies(ciEnv* env) {
247 initialize(env);
248 }
249
250 private:
251 // Check for a valid context type.
252 // Enforce the restriction against array types.
253 static void check_ctxk(ciKlass* ctxk) {
254 assert(ctxk->is_instance_klass(), "java types only");
255 }
256 static void check_ctxk_concrete(ciKlass* ctxk) {
257 assert(is_concrete_klass(ctxk->as_instance_klass()), "must be concrete");
258 }
259 static void check_ctxk_abstract(ciKlass* ctxk) {
260 check_ctxk(ctxk);
261 assert(!is_concrete_klass(ctxk->as_instance_klass()), "must be abstract");
262 }
263
264 void assert_common_1(DepType dept, ciBaseObject* x);
265 void assert_common_2(DepType dept, ciBaseObject* x0, ciBaseObject* x1);
266 void assert_common_3(DepType dept, ciKlass* ctxk, ciBaseObject* x1, ciBaseObject* x2);
267
268 public:
269 // Adding assertions to a new dependency set at compile time:
270 void assert_evol_method(ciMethod* m);
271 void assert_leaf_type(ciKlass* ctxk);
272 void assert_abstract_with_unique_concrete_subtype(ciKlass* ctxk, ciKlass* conck);
273 void assert_abstract_with_no_concrete_subtype(ciKlass* ctxk);
274 void assert_concrete_with_no_concrete_subtype(ciKlass* ctxk);
275 void assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm);
276 void assert_abstract_with_exclusive_concrete_subtypes(ciKlass* ctxk, ciKlass* k1, ciKlass* k2);
277 void assert_exclusive_concrete_methods(ciKlass* ctxk, ciMethod* m1, ciMethod* m2);
278 void assert_has_no_finalizable_subclasses(ciKlass* ctxk);
279 void assert_call_site_target_value(ciCallSite* call_site, ciMethodHandle* method_handle);
280
281 // Define whether a given method or type is concrete.
282 // These methods define the term "concrete" as used in this module.
283 // For this module, an "abstract" class is one which is non-concrete.
284 //
285 // Future optimizations may allow some classes to remain
286 // non-concrete until their first instantiation, and allow some
287 // methods to remain non-concrete until their first invocation.
288 // In that case, there would be a middle ground between concrete
289 // and abstract (as defined by the Java language and VM).
290 static bool is_concrete_klass(Klass* k); // k is instantiable
291 static bool is_concrete_method(Method* m); // m is invocable
292 static Klass* find_finalizable_subclass(Klass* k);
293
294 // These versions of the concreteness queries work through the CI.
295 // The CI versions are allowed to skew sometimes from the VM
296 // (oop-based) versions. The cost of such a difference is a
297 // (safely) aborted compilation, or a deoptimization, or a missed
298 // optimization opportunity.
299 //
300 // In order to prevent spurious assertions, query results must
301 // remain stable within any single ciEnv instance. (I.e., they must
302 // not go back into the VM to get their value; they must cache the
303 // bit in the CI, either eagerly or lazily.)
304 static bool is_concrete_klass(ciInstanceKlass* k); // k appears instantiable
305 static bool is_concrete_method(ciMethod* m); // m appears invocable
306 static bool has_finalizable_subclass(ciInstanceKlass* k);
307
308 // As a general rule, it is OK to compile under the assumption that
309 // a given type or method is concrete, even if it at some future
310 // point becomes abstract. So dependency checking is one-sided, in
311 // that it permits supposedly concrete classes or methods to turn up
312 // as really abstract. (This shouldn't happen, except during class
313 // evolution, but that's the logic of the checking.) However, if a
314 // supposedly abstract class or method suddenly becomes concrete, a
315 // dependency on it must fail.
316
317 // Checking old assertions at run-time (in the VM only):
318 static Klass* check_evol_method(Method* m);
319 static Klass* check_leaf_type(Klass* ctxk);
320 static Klass* check_abstract_with_unique_concrete_subtype(Klass* ctxk, Klass* conck,
321 KlassDepChange* changes = NULL);
322 static Klass* check_abstract_with_no_concrete_subtype(Klass* ctxk,
323 KlassDepChange* changes = NULL);
324 static Klass* check_concrete_with_no_concrete_subtype(Klass* ctxk,
325 KlassDepChange* changes = NULL);
326 static Klass* check_unique_concrete_method(Klass* ctxk, Method* uniqm,
327 KlassDepChange* changes = NULL);
328 static Klass* check_abstract_with_exclusive_concrete_subtypes(Klass* ctxk, Klass* k1, Klass* k2,
329 KlassDepChange* changes = NULL);
330 static Klass* check_exclusive_concrete_methods(Klass* ctxk, Method* m1, Method* m2,
331 KlassDepChange* changes = NULL);
332 static Klass* check_has_no_finalizable_subclasses(Klass* ctxk, KlassDepChange* changes = NULL);
333 static Klass* check_call_site_target_value(oop call_site, oop method_handle, CallSiteDepChange* changes = NULL);
334 // A returned Klass* is NULL if the dependency assertion is still
335 // valid. A non-NULL Klass* is a 'witness' to the assertion
336 // failure, a point in the class hierarchy where the assertion has
337 // been proven false. For example, if check_leaf_type returns
338 // non-NULL, the value is a subtype of the supposed leaf type. This
339 // witness value may be useful for logging the dependency failure.
340 // Note that, when a dependency fails, there may be several possible
341 // witnesses to the failure. The value returned from the check_foo
342 // method is chosen arbitrarily.
343
344 // The 'changes' value, if non-null, requests a limited spot-check
345 // near the indicated recent changes in the class hierarchy.
346 // It is used by DepStream::spot_check_dependency_at.
347
348 // Detecting possible new assertions:
349 static Klass* find_unique_concrete_subtype(Klass* ctxk);
350 static Method* find_unique_concrete_method(Klass* ctxk, Method* m);
351 static int find_exclusive_concrete_subtypes(Klass* ctxk, int klen, Klass* k[]);
352 static int find_exclusive_concrete_methods(Klass* ctxk, int mlen, Method* m[]);
353
354 // Create the encoding which will be stored in an nmethod.
355 void encode_content_bytes();
356
357 address content_bytes() {
358 assert(_content_bytes != NULL, "encode it first");
359 return _content_bytes;
360 }
361 size_t size_in_bytes() {
362 assert(_content_bytes != NULL, "encode it first");
363 return _size_in_bytes;
364 }
365
366 OopRecorder* oop_recorder() { return _oop_recorder; }
367 CompileLog* log() { return _log; }
368
369 void copy_to(nmethod* nm);
370
371 void log_all_dependencies();
372 void log_dependency(DepType dept, int nargs, ciBaseObject* args[]) {
373 write_dependency_to(log(), dept, nargs, args);
374 }
375 void log_dependency(DepType dept,
376 ciBaseObject* x0,
377 ciBaseObject* x1 = NULL,
378 ciBaseObject* x2 = NULL) {
379 if (log() == NULL) return;
380 ciBaseObject* args[max_arg_count];
381 args[0] = x0;
382 args[1] = x1;
383 args[2] = x2;
384 assert(2 < max_arg_count, "");
385 log_dependency(dept, dep_args(dept), args);
386 }
387
388 class DepArgument : public ResourceObj {
389 private:
390 bool _is_oop;
391 bool _valid;
392 void* _value;
393 public:
394 DepArgument() : _is_oop(false), _value(NULL), _valid(false) {}
395 DepArgument(oop v): _is_oop(true), _value(v), _valid(true) {}
396 DepArgument(Metadata* v): _is_oop(false), _value(v), _valid(true) {}
397
398 bool is_null() const { return _value == NULL; }
399 bool is_oop() const { return _is_oop; }
400 bool is_metadata() const { return !_is_oop; }
401 bool is_klass() const { return is_metadata() && metadata_value()->is_klass(); }
402 bool is_method() const { return is_metadata() && metadata_value()->is_method(); }
403
404 oop oop_value() const { assert(_is_oop && _valid, "must be"); return (oop) _value; }
405 Metadata* metadata_value() const { assert(!_is_oop && _valid, "must be"); return (Metadata*) _value; }
406 };
407
408 static void write_dependency_to(CompileLog* log,
409 DepType dept,
410 int nargs, ciBaseObject* args[],
411 Klass* witness = NULL);
412 static void write_dependency_to(CompileLog* log,
413 DepType dept,
414 int nargs, DepArgument args[],
415 Klass* witness = NULL);
416 static void write_dependency_to(xmlStream* xtty,
417 DepType dept,
418 int nargs, DepArgument args[],
419 Klass* witness = NULL);
420 static void print_dependency(DepType dept,
421 int nargs, DepArgument args[],
422 Klass* witness = NULL);
423
424 private:
425 // helper for encoding common context types as zero:
426 static ciKlass* ctxk_encoded_as_null(DepType dept, ciBaseObject* x);
427
428 static Klass* ctxk_encoded_as_null(DepType dept, Metadata* x);
429
430 public:
431 // Use this to iterate over an nmethod's dependency set.
432 // Works on new and old dependency sets.
433 // Usage:
434 //
435 // ;
436 // Dependencies::DepType dept;
437 // for (Dependencies::DepStream deps(nm); deps.next(); ) {
438 // ...
439 // }
440 //
441 // The caller must be in the VM, since oops are not wrapped in handles.
442 class DepStream {
443 private:
444 nmethod* _code; // null if in a compiler thread
445 Dependencies* _deps; // null if not in a compiler thread
446 CompressedReadStream _bytes;
447 #ifdef ASSERT
448 size_t _byte_limit;
449 #endif
450
451 // iteration variables:
452 DepType _type;
453 int _xi[max_arg_count+1];
454
455 void initial_asserts(size_t byte_limit) NOT_DEBUG({});
456
457 inline Metadata* recorded_metadata_at(int i);
458 inline oop recorded_oop_at(int i);
459
460 Klass* check_klass_dependency(KlassDepChange* changes);
461 Klass* check_call_site_dependency(CallSiteDepChange* changes);
462
463 void trace_and_log_witness(Klass* witness);
464
465 public:
466 DepStream(Dependencies* deps)
467 : _deps(deps),
468 _code(NULL),
469 _bytes(deps->content_bytes())
470 {
471 initial_asserts(deps->size_in_bytes());
472 }
473 DepStream(nmethod* code)
474 : _deps(NULL),
475 _code(code),
476 _bytes(code->dependencies_begin())
477 {
478 initial_asserts(code->dependencies_size());
479 }
480
481 bool next();
482
483 DepType type() { return _type; }
484 bool has_oop_argument() { return type() == call_site_target_value; }
485 uintptr_t get_identifier(int i);
486
487 int argument_count() { return dep_args(type()); }
488 int argument_index(int i) { assert(0 <= i && i < argument_count(), "oob");
489 return _xi[i]; }
490 Metadata* argument(int i); // => recorded_oop_at(argument_index(i))
491 oop argument_oop(int i); // => recorded_oop_at(argument_index(i))
492 Klass* context_type();
493
494 bool is_klass_type() { return Dependencies::is_klass_type(type()); }
495
496 Method* method_argument(int i) {
497 Metadata* x = argument(i);
498 assert(x->is_method(), "type");
499 return (Method*) x;
500 }
501 Klass* type_argument(int i) {
502 Metadata* x = argument(i);
503 assert(x->is_klass(), "type");
504 return (Klass*) x;
505 }
506
507 // The point of the whole exercise: Is this dep still OK?
508 Klass* check_dependency() {
509 Klass* result = check_klass_dependency(NULL);
510 if (result != NULL) return result;
511 return check_call_site_dependency(NULL);
512 }
513
514 // A lighter version: Checks only around recent changes in a class
515 // hierarchy. (See Universe::flush_dependents_on.)
516 Klass* spot_check_dependency_at(DepChange& changes);
517
518 // Log the current dependency to xtty or compilation log.
519 void log_dependency(Klass* witness = NULL);
520
521 // Print the current dependency to tty.
522 void print_dependency(Klass* witness = NULL, bool verbose = false);
523 };
524 friend class Dependencies::DepStream;
525
526 static void print_statistics() PRODUCT_RETURN;
527 };
528
529
530 class DependencySignature : public GenericHashtableEntry<DependencySignature, ResourceObj> {
531 private:
532 int _args_count;
533 uintptr_t _argument_hash[Dependencies::max_arg_count];
534 Dependencies::DepType _type;
535
536 public:
537 DependencySignature(Dependencies::DepStream& dep) {
538 _args_count = dep.argument_count();
539 _type = dep.type();
540 for (int i = 0; i < _args_count; i++) {
541 _argument_hash[i] = dep.get_identifier(i);
542 }
543 }
544
545 bool equals(DependencySignature* sig) const;
546 uintptr_t hash() const { return _argument_hash[0] >> 2; }
547
548 int args_count() const { return _args_count; }
549 uintptr_t arg(int idx) const { return _argument_hash[idx]; }
550 Dependencies::DepType type() const { return _type; }
551 };
552
553
554 // Every particular DepChange is a sub-class of this class.
555 class DepChange : public StackObj {
556 public:
557 // What kind of DepChange is this?
558 virtual bool is_klass_change() const { return false; }
559 virtual bool is_call_site_change() const { return false; }
560
561 // Subclass casting with assertions.
562 KlassDepChange* as_klass_change() {
563 assert(is_klass_change(), "bad cast");
564 return (KlassDepChange*) this;
565 }
566 CallSiteDepChange* as_call_site_change() {
567 assert(is_call_site_change(), "bad cast");
568 return (CallSiteDepChange*) this;
569 }
570
571 void print();
572
573 public:
574 enum ChangeType {
575 NO_CHANGE = 0, // an uninvolved klass
576 Change_new_type, // a newly loaded type
577 Change_new_sub, // a super with a new subtype
578 Change_new_impl, // an interface with a new implementation
579 CHANGE_LIMIT,
580 Start_Klass = CHANGE_LIMIT // internal indicator for ContextStream
581 };
582
583 // Usage:
584 // for (DepChange::ContextStream str(changes); str.next(); ) {
585 // Klass* k = str.klass();
586 // switch (str.change_type()) {
587 // ...
588 // }
589 // }
590 class ContextStream : public StackObj {
591 private:
592 DepChange& _changes;
593 friend class DepChange;
594
595 // iteration variables:
596 ChangeType _change_type;
597 Klass* _klass;
598 Array<Klass*>* _ti_base; // i.e., transitive_interfaces
599 int _ti_index;
600 int _ti_limit;
601
602 // start at the beginning:
603 void start();
604
605 public:
606 ContextStream(DepChange& changes)
607 : _changes(changes)
608 { start(); }
609
610 ContextStream(DepChange& changes, No_Safepoint_Verifier& nsv)
611 : _changes(changes)
612 // the nsv argument makes it safe to hold oops like _klass
613 { start(); }
614
615 bool next();
616
617 ChangeType change_type() { return _change_type; }
618 Klass* klass() { return _klass; }
619 };
620 friend class DepChange::ContextStream;
621 };
622
623
624 // A class hierarchy change coming through the VM (under the Compile_lock).
625 // The change is structured as a single new type with any number of supers
626 // and implemented interface types. Other than the new type, any of the
627 // super types can be context types for a relevant dependency, which the
628 // new type could invalidate.
629 class KlassDepChange : public DepChange {
630 private:
631 // each change set is rooted in exactly one new type (at present):
632 KlassHandle _new_type;
633
634 void initialize();
635
636 public:
637 // notes the new type, marks it and all its super-types
638 KlassDepChange(KlassHandle new_type)
639 : _new_type(new_type)
640 {
641 initialize();
642 }
643
644 // cleans up the marks
645 ~KlassDepChange();
646
647 // What kind of DepChange is this?
648 virtual bool is_klass_change() const { return true; }
649
650 Klass* new_type() { return _new_type(); }
651
652 // involves_context(k) is true if k is new_type or any of the super types
653 bool involves_context(Klass* k);
654 };
655
656
657 // A CallSite has changed its target.
658 class CallSiteDepChange : public DepChange {
659 private:
660 Handle _call_site;
661 Handle _method_handle;
662
663 public:
664 CallSiteDepChange(Handle call_site, Handle method_handle)
665 : _call_site(call_site),
666 _method_handle(method_handle)
667 {
668 assert(_call_site() ->is_a(SystemDictionary::CallSite_klass()), "must be");
669 assert(_method_handle()->is_a(SystemDictionary::MethodHandle_klass()), "must be");
670 }
671
672 // What kind of DepChange is this?
673 virtual bool is_call_site_change() const { return true; }
674
675 oop call_site() const { return _call_site(); }
676 oop method_handle() const { return _method_handle(); }
677 };
678
679 #endif // SHARE_VM_CODE_DEPENDENCIES_HPP