1 /*
2 * Copyright (c) 2005, 2026, 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
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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).
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23 */
24
25 #ifndef SHARE_CODE_DEPENDENCIES_HPP
26 #define SHARE_CODE_DEPENDENCIES_HPP
27
28 #include "ci/ciCallSite.hpp"
29 #include "ci/ciKlass.hpp"
30 #include "ci/ciMethod.hpp"
31 #include "ci/ciMethodHandle.hpp"
32 #include "code/compressedStream.hpp"
33 #include "code/nmethod.hpp"
34 #include "memory/resourceArea.hpp"
35 #include "runtime/safepointVerifiers.hpp"
36 #include "utilities/growableArray.hpp"
37
38 //** Dependencies represent assertions (approximate invariants) within
39 // the runtime system, e.g. class hierarchy changes. An example is an
40 // assertion that a given method is not overridden; another example is
41 // that a type has only one concrete subtype. Compiled code which
42 // relies on such assertions must be discarded if they are overturned
43 // by changes in the runtime system. We can think of these assertions
44 // as approximate invariants, because we expect them to be overturned
45 // very infrequently. We are willing to perform expensive recovery
46 // operations when they are overturned. The benefit, of course, is
47 // performing optimistic optimizations (!) on the object code.
48 //
49 // Changes in the class hierarchy due to dynamic linking or
50 // class evolution can violate dependencies. There is enough
51 // indexing between classes and nmethods to make dependency
52 // checking reasonably efficient.
53
54 class ciEnv;
55 class nmethod;
56 class OopRecorder;
57 class xmlStream;
58 class CompileLog;
59 class CompileTask;
60 class DepChange;
61 class KlassDepChange;
62 class NewKlassDepChange;
63 class KlassInitDepChange;
64 class CallSiteDepChange;
65 class NoSafepointVerifier;
66
67 class Dependencies: public ResourceObj {
68 public:
69 // Note: In the comments on dependency types, most uses of the terms
70 // subtype and supertype are used in a "non-strict" or "inclusive"
71 // sense, and are starred to remind the reader of this fact.
72 // Strict uses of the terms use the word "proper".
73 //
74 // Specifically, every class is its own subtype* and supertype*.
75 // (This trick is easier than continually saying things like "Y is a
76 // subtype of X or X itself".)
77 //
78 // Sometimes we write X > Y to mean X is a proper supertype of Y.
79 // The notation X > {Y, Z} means X has proper subtypes Y, Z.
80 // The notation X.m > Y means that Y inherits m from X, while
81 // X.m > Y.m means Y overrides X.m. A star denotes abstractness,
82 // as *I > A, meaning (abstract) interface I is a super type of A,
83 // or A.*m > B.m, meaning B.m implements abstract method A.m.
84 //
85 // In this module, the terms "subtype" and "supertype" refer to
86 // Java-level reference type conversions, as detected by
87 // "instanceof" and performed by "checkcast" operations. The method
88 // Klass::is_subtype_of tests these relations. Note that "subtype"
89 // is richer than "subclass" (as tested by Klass::is_subclass_of),
90 // since it takes account of relations involving interface and array
91 // types.
92 //
93 // To avoid needless complexity, dependencies involving array types
94 // are not accepted. If you need to make an assertion about an
95 // array type, make the assertion about its corresponding element
96 // types. Any assertion that might change about an array type can
97 // be converted to an assertion about its element type.
98 //
99 // Most dependencies are evaluated over a "context type" CX, which
100 // stands for the set Subtypes(CX) of every Java type that is a subtype*
101 // of CX. When the system loads a new class or interface N, it is
102 // responsible for re-evaluating changed dependencies whose context
103 // type now includes N, that is, all super types of N.
104 //
105 enum DepType {
106 // _type is initially set to -1, to prevent "already at end" assert
107 undefined_dependency = -1,
108
109 end_marker = 0,
110
111 // An 'evol' dependency simply notes that the contents of the
112 // method were used. If it evolves (is replaced), the nmethod
113 // must be recompiled. No other dependencies are implied.
114 evol_method,
115 FIRST_TYPE = evol_method,
116
117 // A context type CX is a leaf it if has no proper subtype.
118 leaf_type,
119
120 // An abstract class CX has exactly one concrete subtype CC.
121 abstract_with_unique_concrete_subtype,
122
123 // Given a method M1 and a context class CX, the set MM(CX, M1, RC1, RM1) of
124 // "concrete matching methods" in CX of M1 is the set of every
125 // concrete M2 for which it is possible to create an invokevirtual
126 // or invokeinterface call site that can reach either M1 or M2.
127 // That is, M1 and M2 share a name, signature, and vtable index.
128 // We wish to notice when the set MM(CX, M1, RC1, RM1) is just {M1}, or
129 // perhaps a set of two {M1,M2}, and issue dependencies on this.
130
131 // The set MM(CX, M1, RC1, RM1) can be computed by starting with any matching
132 // concrete M2 that is inherited into CX, and then walking the
133 // subtypes* of CX looking for concrete definitions.
134
135 // The parameters to this dependency are the context class CX, the method M1,
136 // the resolved class RC1, and the resolved method RM1. M1 must be either inherited in CX
137 // or defined in a subtype* of CX. It asserts that MM(CX, M1, RC1, RM1) is
138 // no greater than {M1}. RC1 and RM1 are used to improve the precision of the analysis.
139 unique_concrete_method, // one unique concrete method under CX
140
141 // This dependency asserts that interface CX has a unique implementor class.
142 unique_implementor, // one unique implementor under CX
143
144 // This dependency asserts that no instances of class or it's
145 // subclasses require finalization registration.
146 no_finalizable_subclasses,
147
148 // This dependency asserts when the CallSite.target value changed.
149 call_site_target_value,
150
151 TYPE_LIMIT
152 };
153 enum {
154 LG2_TYPE_LIMIT = 4, // assert(TYPE_LIMIT <= (1<<LG2_TYPE_LIMIT))
155
156 // handy categorizations of dependency types:
157 all_types = ((1 << TYPE_LIMIT) - 1) & ((~0u) << FIRST_TYPE),
158
159 non_klass_types = (1 << call_site_target_value),
160 klass_types = all_types & ~non_klass_types,
161
162 non_ctxk_types = (1 << evol_method) | (1 << call_site_target_value),
163 implicit_ctxk_types = 0,
164 explicit_ctxk_types = all_types & ~(non_ctxk_types | implicit_ctxk_types),
165
166 max_arg_count = 4, // current maximum number of arguments (incl. ctxk)
167
168 // A "context type" is a class or interface that
169 // provides context for evaluating a dependency.
170 // When present, it is one of the arguments (dep_context_arg).
171 //
172 // If a dependency does not have a context type, there is a
173 // default context, depending on the type of the dependency.
174 // This bit signals that a default context has been compressed away.
175 default_context_type_bit = (1<<LG2_TYPE_LIMIT)
176 };
177
178 static const char* dep_name(DepType dept);
179 static int dep_args(DepType dept);
180
181 static bool is_klass_type( DepType dept) { return dept_in_mask(dept, klass_types ); }
182
183 static bool has_explicit_context_arg(DepType dept) { return dept_in_mask(dept, explicit_ctxk_types); }
184 static bool has_implicit_context_arg(DepType dept) { return dept_in_mask(dept, implicit_ctxk_types); }
185
186 static int dep_context_arg(DepType dept) { return has_explicit_context_arg(dept) ? 0 : -1; }
187 static int dep_implicit_context_arg(DepType dept) { return has_implicit_context_arg(dept) ? 0 : -1; }
188
189 static void check_valid_dependency_type(DepType dept);
190
191 private:
192 // State for writing a new set of dependencies:
193 GrowableArray<int>* _dep_seen; // (seen[h->ident] & (1<<dept))
194 GrowableArray<ciBaseObject*>* _deps[TYPE_LIMIT];
195
196 static const char* _dep_name[TYPE_LIMIT];
197 static int _dep_args[TYPE_LIMIT];
198
199 static bool dept_in_mask(DepType dept, int mask) {
200 return (int)dept >= 0 && dept < TYPE_LIMIT && ((1<<dept) & mask) != 0;
201 }
202
203 bool note_dep_seen(int dept, ciBaseObject* x) {
204 assert(dept < BitsPerInt, "oob");
205 int x_id = x->ident();
206 assert(_dep_seen != nullptr, "deps must be writable");
207 int seen = _dep_seen->at_grow(x_id, 0);
208 _dep_seen->at_put(x_id, seen | (1<<dept));
209 // return true if we've already seen dept/x
210 return (seen & (1<<dept)) != 0;
211 }
212
213 bool maybe_merge_ctxk(GrowableArray<ciBaseObject*>* deps,
214 int ctxk_i, ciKlass* ctxk);
215
216 void sort_all_deps();
217 size_t estimate_size_in_bytes();
218
219 // Initialize _deps, etc.
220 void initialize(ciEnv* env);
221
222 // State for making a new set of dependencies:
223 OopRecorder* _oop_recorder;
224
225 // Logging support
226 CompileLog* _log;
227
228 address _content_bytes; // everything but the oop references, encoded
229 size_t _size_in_bytes;
230
231 public:
232 // Make a new empty dependencies set.
233 Dependencies(ciEnv* env) {
234 initialize(env);
235 }
236
237 private:
238 // Check for a valid context type.
239 // Enforce the restriction against array types.
240 static void check_ctxk(ciKlass* ctxk) {
241 assert(ctxk->is_instance_klass(), "java types only");
242 }
243 static void check_ctxk_concrete(ciKlass* ctxk) {
244 assert(is_concrete_klass(ctxk->as_instance_klass()), "must be concrete");
245 }
246 static void check_ctxk_abstract(ciKlass* ctxk) {
247 check_ctxk(ctxk);
248 assert(!is_concrete_klass(ctxk->as_instance_klass()), "must be abstract");
249 }
250 static void check_unique_method(ciKlass* ctxk, ciMethod* m) {
251 assert(!m->can_be_statically_bound(ctxk->as_instance_klass()) || ctxk->is_interface(), "redundant");
252 }
253 static void check_unique_implementor(ciInstanceKlass* ctxk, ciInstanceKlass* uniqk) {
254 assert(ctxk->implementor() == uniqk, "not a unique implementor");
255 }
256
257 void assert_common_1(DepType dept, ciBaseObject* x);
258 void assert_common_2(DepType dept, ciBaseObject* x0, ciBaseObject* x1);
259 void assert_common_4(DepType dept, ciKlass* ctxk, ciBaseObject* x1, ciBaseObject* x2, ciBaseObject* x3);
260
261 public:
262 // Adding assertions to a new dependency set at compile time:
263 void assert_evol_method(ciMethod* m);
264 void assert_leaf_type(ciKlass* ctxk);
265 void assert_abstract_with_unique_concrete_subtype(ciKlass* ctxk, ciKlass* conck);
266 void assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm, ciKlass* resolved_klass, ciMethod* resolved_method);
267 void assert_unique_implementor(ciInstanceKlass* ctxk, ciInstanceKlass* uniqk);
268 void assert_has_no_finalizable_subclasses(ciKlass* ctxk);
269 void assert_call_site_target_value(ciCallSite* call_site, ciMethodHandle* method_handle);
270
271 // Define whether a given method or type is concrete.
272 // These methods define the term "concrete" as used in this module.
273 // For this module, an "abstract" class is one which is non-concrete.
274 //
275 // Future optimizations may allow some classes to remain
276 // non-concrete until their first instantiation, and allow some
277 // methods to remain non-concrete until their first invocation.
278 // In that case, there would be a middle ground between concrete
279 // and abstract (as defined by the Java language and VM).
280 static bool is_concrete_klass(Klass* k); // k is instantiable
281 static bool is_concrete_method(Method* m, Klass* k); // m is invocable
282 static Klass* find_finalizable_subclass(InstanceKlass* ik);
283
284 // These versions of the concreteness queries work through the CI.
285 // The CI versions are allowed to skew sometimes from the VM
286 // (oop-based) versions. The cost of such a difference is a
287 // (safely) aborted compilation, or a deoptimization, or a missed
288 // optimization opportunity.
289 //
290 // In order to prevent spurious assertions, query results must
291 // remain stable within any single ciEnv instance. (I.e., they must
292 // not go back into the VM to get their value; they must cache the
293 // bit in the CI, either eagerly or lazily.)
294 static bool is_concrete_klass(ciInstanceKlass* k); // k appears instantiable
295 static bool has_finalizable_subclass(ciInstanceKlass* k);
296
297 // As a general rule, it is OK to compile under the assumption that
298 // a given type or method is concrete, even if it at some future
299 // point becomes abstract. So dependency checking is one-sided, in
300 // that it permits supposedly concrete classes or methods to turn up
301 // as really abstract. (This shouldn't happen, except during class
302 // evolution, but that's the logic of the checking.) However, if a
303 // supposedly abstract class or method suddenly becomes concrete, a
304 // dependency on it must fail.
305
306 // Checking old assertions at run-time (in the VM only):
307 static Klass* check_evol_method(Method* m);
308 static Klass* check_leaf_type(InstanceKlass* ctxk);
309 static Klass* check_abstract_with_unique_concrete_subtype(InstanceKlass* ctxk, Klass* conck, NewKlassDepChange* changes = nullptr);
310 static Klass* check_unique_implementor(InstanceKlass* ctxk, Klass* uniqk, NewKlassDepChange* changes = nullptr);
311 static Klass* check_unique_concrete_method(InstanceKlass* ctxk, Method* uniqm, Klass* resolved_klass, Method* resolved_method, KlassDepChange* changes = nullptr);
312 static Klass* check_has_no_finalizable_subclasses(InstanceKlass* ctxk, NewKlassDepChange* changes = nullptr);
313 static Klass* check_call_site_target_value(oop call_site, oop method_handle, CallSiteDepChange* changes = nullptr);
314 // A returned Klass* is nullptr if the dependency assertion is still
315 // valid. A non-nullptr Klass* is a 'witness' to the assertion
316 // failure, a point in the class hierarchy where the assertion has
317 // been proven false. For example, if check_leaf_type returns
318 // non-nullptr, the value is a subtype of the supposed leaf type. This
319 // witness value may be useful for logging the dependency failure.
320 // Note that, when a dependency fails, there may be several possible
321 // witnesses to the failure. The value returned from the check_foo
322 // method is chosen arbitrarily.
323
324 // The 'changes' value, if non-null, requests a limited spot-check
325 // near the indicated recent changes in the class hierarchy.
326 // It is used by DepStream::spot_check_dependency_at.
327
328 // Detecting possible new assertions:
329 static Klass* find_unique_concrete_subtype(InstanceKlass* ctxk);
330
331 static Method* find_unique_concrete_method(InstanceKlass* ctxk, Method* m, Klass* resolved_klass, Method* resolved_method);
332
333 #ifdef ASSERT
334 static bool verify_method_context(InstanceKlass* ctxk, Method* m);
335 #endif // ASSERT
336
337 // Create the encoding which will be stored in an nmethod.
338 void encode_content_bytes();
339
340 address content_bytes() {
341 assert(_content_bytes != nullptr, "encode it first");
342 return _content_bytes;
343 }
344 size_t size_in_bytes() {
345 assert(_content_bytes != nullptr, "encode it first");
346 return _size_in_bytes;
347 }
348
349 OopRecorder* oop_recorder() { return _oop_recorder; }
350 CompileLog* log() { return _log; }
351
352 void copy_to(nmethod* nm);
353
354 static bool _verify_in_progress; // turn off logging dependencies
355
356 DepType validate_dependencies(CompileTask* task, char** failure_detail = nullptr);
357
358 void log_all_dependencies();
359
360 void log_dependency(DepType dept, GrowableArray<ciBaseObject*>* args) {
361 ResourceMark rm;
362 int argslen = args->length();
363 write_dependency_to(log(), dept, args);
364 guarantee(argslen == args->length(),
365 "args array cannot grow inside nested ResoureMark scope");
366 }
367
368 void log_dependency(DepType dept,
369 ciBaseObject* x0,
370 ciBaseObject* x1 = nullptr,
371 ciBaseObject* x2 = nullptr,
372 ciBaseObject* x3 = nullptr) {
373 if (log() == nullptr) {
374 return;
375 }
376 ResourceMark rm;
377 GrowableArray<ciBaseObject*>* ciargs =
378 new GrowableArray<ciBaseObject*>(dep_args(dept));
379 assert (x0 != nullptr, "no log x0");
380 ciargs->push(x0);
381
382 if (x1 != nullptr) {
383 ciargs->push(x1);
384 }
385 if (x2 != nullptr) {
386 ciargs->push(x2);
387 }
388 if (x3 != nullptr) {
389 ciargs->push(x3);
390 }
391 assert(ciargs->length() == dep_args(dept), "");
392 log_dependency(dept, ciargs);
393 }
394
395 class DepArgument : public ResourceObj {
396 private:
397 bool _is_oop;
398 bool _valid;
399 void* _value;
400 public:
401 DepArgument() : _is_oop(false), _valid(false), _value(nullptr) {}
402 DepArgument(oop v): _is_oop(true), _valid(true), _value(v) {}
403 DepArgument(Metadata* v): _is_oop(false), _valid(true), _value(v) {}
404
405 bool is_null() const { return _value == nullptr; }
406 bool is_oop() const { return _is_oop; }
407 bool is_metadata() const { return !_is_oop; }
408 bool is_klass() const { return is_metadata() && metadata_value()->is_klass(); }
409 bool is_method() const { return is_metadata() && metadata_value()->is_method(); }
410
411 oop oop_value() const { assert(_is_oop && _valid, "must be"); return cast_to_oop(_value); }
412 Metadata* metadata_value() const { assert(!_is_oop && _valid, "must be"); return (Metadata*) _value; }
413 };
414
415 static void print_dependency(DepType dept,
416 GrowableArray<DepArgument>* args,
417 Klass* witness = nullptr, outputStream* st = tty);
418
419 private:
420 // helper for encoding common context types as zero:
421 static ciKlass* ctxk_encoded_as_null(DepType dept, ciBaseObject* x);
422
423 static Klass* ctxk_encoded_as_null(DepType dept, Metadata* x);
424
425 static void write_dependency_to(CompileLog* log,
426 DepType dept,
427 GrowableArray<ciBaseObject*>* args,
428 Klass* witness = nullptr);
429 static void write_dependency_to(CompileLog* log,
430 DepType dept,
431 GrowableArray<DepArgument>* args,
432 Klass* witness = nullptr);
433 static void write_dependency_to(xmlStream* xtty,
434 DepType dept,
435 GrowableArray<DepArgument>* args,
436 Klass* witness = nullptr);
437 public:
438 // Use this to iterate over an nmethod's dependency set.
439 // Works on new and old dependency sets.
440 // Usage:
441 //
442 // ;
443 // Dependencies::DepType dept;
444 // for (Dependencies::DepStream deps(nm); deps.next(); ) {
445 // ...
446 // }
447 //
448 // The caller must be in the VM, since oops are not wrapped in handles.
449 class DepStream {
450 private:
451 nmethod* _code; // null if in a compiler thread
452 Dependencies* _deps; // null if not in a compiler thread
453 CompressedReadStream _bytes;
454 #ifdef ASSERT
455 size_t _byte_limit;
456 #endif
457
458 // iteration variables:
459 DepType _type;
460 int _xi[max_arg_count+1];
461
462 void initial_asserts(size_t byte_limit) NOT_DEBUG({});
463
464 inline Metadata* recorded_metadata_at(int i);
465 inline oop recorded_oop_at(int i);
466
467 Klass* check_klass_dependency(KlassDepChange* changes);
468 Klass* check_new_klass_dependency(NewKlassDepChange* changes);
469 Klass* check_klass_init_dependency(KlassInitDepChange* changes);
470 Klass* check_call_site_dependency(CallSiteDepChange* changes);
471
472 void trace_and_log_witness(Klass* witness);
473
474 public:
475 DepStream(Dependencies* deps)
476 : _code(nullptr),
477 _deps(deps),
478 _bytes(deps->content_bytes())
479 {
480 initial_asserts(deps->size_in_bytes());
481 }
482 DepStream(nmethod* code)
483 : _code(code),
484 _deps(nullptr),
485 _bytes(code->dependencies_begin())
486 {
487 initial_asserts(code->dependencies_size());
488 }
489
490 bool next();
491
492 DepType type() { return _type; }
493 bool is_oop_argument(int i) { return type() == call_site_target_value; }
494 uintptr_t get_identifier(int i);
495
496 int argument_count() { return dep_args(type()); }
497 int argument_index(int i) { assert(0 <= i && i < argument_count(), "oob");
498 return _xi[i]; }
499 Metadata* argument(int i); // => recorded_oop_at(argument_index(i))
500 oop argument_oop(int i); // => recorded_oop_at(argument_index(i))
501 InstanceKlass* context_type();
502
503 bool is_klass_type() { return Dependencies::is_klass_type(type()); }
504
505 Method* method_argument(int i) {
506 Metadata* x = argument(i);
507 assert(x->is_method(), "type");
508 return (Method*) x;
509 }
510 Klass* type_argument(int i) {
511 Metadata* x = argument(i);
512 assert(x->is_klass(), "type");
513 return (Klass*) x;
514 }
515
516 // The point of the whole exercise: Is this dep still OK?
517 Klass* check_dependency() {
518 Klass* result = check_klass_dependency(nullptr);
519 if (result != nullptr) return result;
520 return check_call_site_dependency(nullptr);
521 }
522
523 // A lighter version: Checks only around recent changes in a class
524 // hierarchy. (See Universe::flush_dependents_on.)
525 Klass* spot_check_dependency_at(DepChange& changes);
526
527 // Log the current dependency to xtty or compilation log.
528 void log_dependency(Klass* witness = nullptr);
529
530 // Print the current dependency to tty.
531 void print_dependency(outputStream* st, Klass* witness = nullptr, bool verbose = false);
532 };
533 friend class Dependencies::DepStream;
534
535 NOT_PRODUCT(static void print_statistics();)
536 };
537
538
539 class DependencySignature : public ResourceObj {
540 private:
541 int _args_count;
542 uintptr_t _argument_hash[Dependencies::max_arg_count];
543 Dependencies::DepType _type;
544
545 public:
546 DependencySignature(Dependencies::DepStream& dep) {
547 _args_count = dep.argument_count();
548 _type = dep.type();
549 for (int i = 0; i < _args_count; i++) {
550 _argument_hash[i] = dep.get_identifier(i);
551 }
552 }
553
554 static bool equals(DependencySignature const& s1, DependencySignature const& s2);
555 static unsigned hash (DependencySignature const& s1) { return (unsigned)(s1.arg(0) >> 2); }
556
557 int args_count() const { return _args_count; }
558 uintptr_t arg(int idx) const { return _argument_hash[idx]; }
559 Dependencies::DepType type() const { return _type; }
560
561 };
562
563
564 // Every particular DepChange is a sub-class of this class.
565 class DepChange : public StackObj {
566 public:
567 // What kind of DepChange is this?
568 virtual bool is_klass_change() const { return false; }
569 virtual bool is_new_klass_change() const { return false; }
570 virtual bool is_klass_init_change() const { return false; }
571 virtual bool is_call_site_change() const { return false; }
572
573 // Subclass casting with assertions.
574 KlassDepChange* as_klass_change() {
575 assert(is_klass_change(), "bad cast");
576 return (KlassDepChange*) this;
577 }
578 NewKlassDepChange* as_new_klass_change() {
579 assert(is_new_klass_change(), "bad cast");
580 return (NewKlassDepChange*) this;
581 }
582 KlassInitDepChange* as_klass_init_change() {
583 assert(is_klass_init_change(), "bad cast");
584 return (KlassInitDepChange*) this;
585 }
586 CallSiteDepChange* as_call_site_change() {
587 assert(is_call_site_change(), "bad cast");
588 return (CallSiteDepChange*) this;
589 }
590
591 void print();
592 void print_on(outputStream* st);
593
594 public:
595 enum ChangeType {
596 NO_CHANGE = 0, // an uninvolved klass
597 Change_new_type, // a newly loaded type
598 Change_new_sub, // a super with a new subtype
599 Change_new_impl, // an interface with a new implementation
600 CHANGE_LIMIT,
601 Start_Klass = CHANGE_LIMIT // internal indicator for ContextStream
602 };
603
604 // Usage:
605 // for (DepChange::ContextStream str(changes); str.next(); ) {
606 // InstanceKlass* k = str.klass();
607 // switch (str.change_type()) {
608 // ...
609 // }
610 // }
611 class ContextStream : public StackObj {
612 private:
613 DepChange& _changes;
614 friend class DepChange;
615
616 // iteration variables:
617 ChangeType _change_type;
618 InstanceKlass* _klass;
619 Array<InstanceKlass*>* _ti_base; // i.e., transitive_interfaces
620 int _ti_index;
621 int _ti_limit;
622
623 // start at the beginning:
624 void start();
625
626 public:
627 ContextStream(DepChange& changes)
628 : _changes(changes)
629 { start(); }
630
631 ContextStream(DepChange& changes, NoSafepointVerifier& nsv)
632 : _changes(changes)
633 // the nsv argument makes it safe to hold oops like _klass
634 { start(); }
635
636 bool next();
637
638 ChangeType change_type() { return _change_type; }
639 InstanceKlass* klass() { return _klass; }
640 };
641 friend class DepChange::ContextStream;
642 };
643
644
645 // A class hierarchy change coming through the VM (under the Compile_lock).
646 // The change is structured as a single type with any number of supers
647 // and implemented interface types. Other than the type, any of the
648 // super types can be context types for a relevant dependency, which the
649 // type could invalidate.
650 class KlassDepChange : public DepChange {
651 private:
652 // each change set is rooted in exactly one type (at present):
653 InstanceKlass* _type;
654
655 void initialize();
656
657 protected:
658 // notes the type, marks it and all its super-types
659 KlassDepChange(InstanceKlass* type) : _type(type) {
660 initialize();
661 }
662
663 // cleans up the marks
664 ~KlassDepChange();
665
666 public:
667 // What kind of DepChange is this?
668 virtual bool is_klass_change() const { return true; }
669
670 InstanceKlass* type() { return _type; }
671
672 // involves_context(k) is true if k == _type or any of its super types
673 bool involves_context(Klass* k);
674 };
675
676 // A class hierarchy change: new type is loaded.
677 class NewKlassDepChange : public KlassDepChange {
678 public:
679 NewKlassDepChange(InstanceKlass* new_type) : KlassDepChange(new_type) {}
680
681 // What kind of DepChange is this?
682 virtual bool is_new_klass_change() const { return true; }
683
684 InstanceKlass* new_type() { return type(); }
685 };
686
687 // Change in initialization state of a loaded class.
688 class KlassInitDepChange : public KlassDepChange {
689 public:
690 KlassInitDepChange(InstanceKlass* type) : KlassDepChange(type) {}
691
692 // What kind of DepChange is this?
693 virtual bool is_klass_init_change() const { return true; }
694 };
695
696 // A CallSite has changed its target.
697 class CallSiteDepChange : public DepChange {
698 private:
699 Handle _call_site;
700 Handle _method_handle;
701
702 public:
703 CallSiteDepChange(Handle call_site, Handle method_handle);
704
705 // What kind of DepChange is this?
706 virtual bool is_call_site_change() const { return true; }
707
708 oop call_site() const { return _call_site(); }
709 oop method_handle() const { return _method_handle(); }
710 };
711
712 #endif // SHARE_CODE_DEPENDENCIES_HPP