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.
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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
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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 // This dependency means that some argument of this method was
118 // assumed to be always passed in scalarized form. In case of
119 // a mismatch with two super methods (one assuming scalarized
120 // and one assuming non-scalarized), all callers of this method
121 // (via virtual calls) now need to be recompiled.
122 // See CompiledEntrySignature::compute_calling_conventions
123 mismatch_calling_convention,
124
125 // A context type CX is a leaf it if has no proper subtype.
126 leaf_type,
127
128 // An abstract class CX has exactly one concrete subtype CC.
129 abstract_with_unique_concrete_subtype,
130
131 // Given a method M1 and a context class CX, the set MM(CX, M1, RC1, RM1) of
132 // "concrete matching methods" in CX of M1 is the set of every
133 // concrete M2 for which it is possible to create an invokevirtual
134 // or invokeinterface call site that can reach either M1 or M2.
135 // That is, M1 and M2 share a name, signature, and vtable index.
136 // We wish to notice when the set MM(CX, M1, RC1, RM1) is just {M1}, or
137 // perhaps a set of two {M1,M2}, and issue dependencies on this.
138
139 // The set MM(CX, M1, RC1, RM1) can be computed by starting with any matching
140 // concrete M2 that is inherited into CX, and then walking the
141 // subtypes* of CX looking for concrete definitions.
142
143 // The parameters to this dependency are the context class CX, the method M1,
144 // the resolved class RC1, and the resolved method RM1. M1 must be either inherited in CX
145 // or defined in a subtype* of CX. It asserts that MM(CX, M1, RC1, RM1) is
146 // no greater than {M1}. RC1 and RM1 are used to improve the precision of the analysis.
147 unique_concrete_method, // one unique concrete method under CX
148
149 // This dependency asserts that interface CX has a unique implementor class.
150 unique_implementor, // one unique implementor under CX
151
152 // This dependency asserts that no instances of class or it's
153 // subclasses require finalization registration.
154 no_finalizable_subclasses,
155
156 // This dependency asserts when the CallSite.target value changed.
157 call_site_target_value,
158
159 TYPE_LIMIT
160 };
161 enum {
162 LG2_TYPE_LIMIT = 4, // assert(TYPE_LIMIT <= (1<<LG2_TYPE_LIMIT))
163
164 // handy categorizations of dependency types:
165 all_types = ((1 << TYPE_LIMIT) - 1) & ((~0u) << FIRST_TYPE),
166
167 non_klass_types = (1 << call_site_target_value),
168 klass_types = all_types & ~non_klass_types,
169
170 non_ctxk_types = (1 << evol_method) | (1 << mismatch_calling_convention) | (1 << call_site_target_value),
171 implicit_ctxk_types = 0,
172 explicit_ctxk_types = all_types & ~(non_ctxk_types | implicit_ctxk_types),
173
174 max_arg_count = 4, // current maximum number of arguments (incl. ctxk)
175
176 // A "context type" is a class or interface that
177 // provides context for evaluating a dependency.
178 // When present, it is one of the arguments (dep_context_arg).
179 //
180 // If a dependency does not have a context type, there is a
181 // default context, depending on the type of the dependency.
182 // This bit signals that a default context has been compressed away.
183 default_context_type_bit = (1<<LG2_TYPE_LIMIT),
184
185 method_types = (1 << evol_method) | (1 << mismatch_calling_convention),
186 };
187
188 static const char* dep_name(DepType dept);
189 static int dep_args(DepType dept);
190
191 static bool is_klass_type( DepType dept) { return dept_in_mask(dept, klass_types ); }
192
193 static bool has_explicit_context_arg(DepType dept) { return dept_in_mask(dept, explicit_ctxk_types); }
194 static bool has_implicit_context_arg(DepType dept) { return dept_in_mask(dept, implicit_ctxk_types); }
195
196 static bool has_method_dep(DepType dept) { return dept_in_mask(dept, method_types); }
197
198 static int dep_context_arg(DepType dept) { return has_explicit_context_arg(dept) ? 0 : -1; }
199 static int dep_implicit_context_arg(DepType dept) { return has_implicit_context_arg(dept) ? 0 : -1; }
200
201 static void check_valid_dependency_type(DepType dept);
202
203 private:
204 // State for writing a new set of dependencies:
205 GrowableArray<int>* _dep_seen; // (seen[h->ident] & (1<<dept))
206 GrowableArray<ciBaseObject*>* _deps[TYPE_LIMIT];
207
208 static const char* _dep_name[TYPE_LIMIT];
209 static int _dep_args[TYPE_LIMIT];
210
211 static bool dept_in_mask(DepType dept, int mask) {
212 return (int)dept >= 0 && dept < TYPE_LIMIT && ((1<<dept) & mask) != 0;
213 }
214
215 bool note_dep_seen(int dept, ciBaseObject* x) {
216 assert(dept < BitsPerInt, "oob");
217 int x_id = x->ident();
218 assert(_dep_seen != nullptr, "deps must be writable");
219 int seen = _dep_seen->at_grow(x_id, 0);
220 _dep_seen->at_put(x_id, seen | (1<<dept));
221 // return true if we've already seen dept/x
222 return (seen & (1<<dept)) != 0;
223 }
224
225 bool maybe_merge_ctxk(GrowableArray<ciBaseObject*>* deps,
226 int ctxk_i, ciKlass* ctxk);
227
228 void sort_all_deps();
229 size_t estimate_size_in_bytes();
230
231 // Initialize _deps, etc.
232 void initialize(ciEnv* env);
233
234 // State for making a new set of dependencies:
235 OopRecorder* _oop_recorder;
236
237 // Logging support
238 CompileLog* _log;
239
240 address _content_bytes; // everything but the oop references, encoded
241 size_t _size_in_bytes;
242
243 public:
244 // Make a new empty dependencies set.
245 Dependencies(ciEnv* env) {
246 initialize(env);
247 }
248
249 private:
250 // Check for a valid context type.
251 // Enforce the restriction against array types.
252 static void check_ctxk(ciKlass* ctxk) {
253 assert(ctxk->is_instance_klass(), "java types only");
254 }
255 static void check_ctxk_concrete(ciKlass* ctxk) {
256 assert(is_concrete_klass(ctxk->as_instance_klass()), "must be concrete");
257 }
258 static void check_ctxk_abstract(ciKlass* ctxk) {
259 check_ctxk(ctxk);
260 assert(!is_concrete_klass(ctxk->as_instance_klass()), "must be abstract");
261 }
262 static void check_unique_method(ciKlass* ctxk, ciMethod* m) {
263 assert(!m->can_be_statically_bound(ctxk->as_instance_klass()) || ctxk->is_interface(), "redundant");
264 }
265 static void check_unique_implementor(ciInstanceKlass* ctxk, ciInstanceKlass* uniqk) {
266 assert(ctxk->implementor() == uniqk, "not a unique implementor");
267 }
268
269 void assert_common_1(DepType dept, ciBaseObject* x);
270 void assert_common_2(DepType dept, ciBaseObject* x0, ciBaseObject* x1);
271 void assert_common_4(DepType dept, ciKlass* ctxk, ciBaseObject* x1, ciBaseObject* x2, ciBaseObject* x3);
272
273 public:
274 // Adding assertions to a new dependency set at compile time:
275 void assert_evol_method(ciMethod* m);
276 void assert_mismatch_calling_convention(ciMethod* m);
277 void assert_leaf_type(ciKlass* ctxk);
278 void assert_abstract_with_unique_concrete_subtype(ciKlass* ctxk, ciKlass* conck);
279 void assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm, ciKlass* resolved_klass, ciMethod* resolved_method);
280 void assert_unique_implementor(ciInstanceKlass* ctxk, ciInstanceKlass* uniqk);
281 void assert_has_no_finalizable_subclasses(ciKlass* ctxk);
282 void assert_call_site_target_value(ciCallSite* call_site, ciMethodHandle* method_handle);
283
284 // Define whether a given method or type is concrete.
285 // These methods define the term "concrete" as used in this module.
286 // For this module, an "abstract" class is one which is non-concrete.
287 //
288 // Future optimizations may allow some classes to remain
289 // non-concrete until their first instantiation, and allow some
290 // methods to remain non-concrete until their first invocation.
291 // In that case, there would be a middle ground between concrete
292 // and abstract (as defined by the Java language and VM).
293 static bool is_concrete_klass(Klass* k); // k is instantiable
294 static bool is_concrete_method(Method* m, Klass* k); // m is invocable
295 static Klass* find_finalizable_subclass(InstanceKlass* ik);
296
297 // These versions of the concreteness queries work through the CI.
298 // The CI versions are allowed to skew sometimes from the VM
299 // (oop-based) versions. The cost of such a difference is a
300 // (safely) aborted compilation, or a deoptimization, or a missed
301 // optimization opportunity.
302 //
303 // In order to prevent spurious assertions, query results must
304 // remain stable within any single ciEnv instance. (I.e., they must
305 // not go back into the VM to get their value; they must cache the
306 // bit in the CI, either eagerly or lazily.)
307 static bool is_concrete_klass(ciInstanceKlass* k); // k appears instantiable
308 static bool has_finalizable_subclass(ciInstanceKlass* k);
309
310 // As a general rule, it is OK to compile under the assumption that
311 // a given type or method is concrete, even if it at some future
312 // point becomes abstract. So dependency checking is one-sided, in
313 // that it permits supposedly concrete classes or methods to turn up
314 // as really abstract. (This shouldn't happen, except during class
315 // evolution, but that's the logic of the checking.) However, if a
316 // supposedly abstract class or method suddenly becomes concrete, a
317 // dependency on it must fail.
318
319 // Checking old assertions at run-time (in the VM only):
320 static Klass* check_evol_method(Method* m);
321 static Klass* check_mismatch_calling_convention(Method* m);
322 static Klass* check_leaf_type(InstanceKlass* ctxk);
323 static Klass* check_abstract_with_unique_concrete_subtype(InstanceKlass* ctxk, Klass* conck, NewKlassDepChange* changes = nullptr);
324 static Klass* check_unique_implementor(InstanceKlass* ctxk, Klass* uniqk, NewKlassDepChange* changes = nullptr);
325 static Klass* check_unique_concrete_method(InstanceKlass* ctxk, Method* uniqm, Klass* resolved_klass, Method* resolved_method, KlassDepChange* changes = nullptr);
326 static Klass* check_has_no_finalizable_subclasses(InstanceKlass* ctxk, NewKlassDepChange* changes = nullptr);
327 static Klass* check_call_site_target_value(oop call_site, oop method_handle, CallSiteDepChange* changes = nullptr);
328 // A returned Klass* is nullptr if the dependency assertion is still
329 // valid. A non-nullptr Klass* is a 'witness' to the assertion
330 // failure, a point in the class hierarchy where the assertion has
331 // been proven false. For example, if check_leaf_type returns
332 // non-nullptr, the value is a subtype of the supposed leaf type. This
333 // witness value may be useful for logging the dependency failure.
334 // Note that, when a dependency fails, there may be several possible
335 // witnesses to the failure. The value returned from the check_foo
336 // method is chosen arbitrarily.
337
338 // The 'changes' value, if non-null, requests a limited spot-check
339 // near the indicated recent changes in the class hierarchy.
340 // It is used by DepStream::spot_check_dependency_at.
341
342 // Detecting possible new assertions:
343 static Klass* find_unique_concrete_subtype(InstanceKlass* ctxk);
344
345 static Method* find_unique_concrete_method(InstanceKlass* ctxk, Method* m, Klass* resolved_klass, Method* resolved_method);
346
347 #ifdef ASSERT
348 static bool verify_method_context(InstanceKlass* ctxk, Method* m);
349 #endif // ASSERT
350
351 // Create the encoding which will be stored in an nmethod.
352 void encode_content_bytes();
353
354 address content_bytes() {
355 assert(_content_bytes != nullptr, "encode it first");
356 return _content_bytes;
357 }
358 size_t size_in_bytes() {
359 assert(_content_bytes != nullptr, "encode it first");
360 return _size_in_bytes;
361 }
362
363 OopRecorder* oop_recorder() { return _oop_recorder; }
364 CompileLog* log() { return _log; }
365
366 void copy_to(nmethod* nm);
367
368 static bool _verify_in_progress; // turn off logging dependencies
369
370 DepType validate_dependencies(CompileTask* task, char** failure_detail = nullptr);
371
372 void log_all_dependencies();
373
374 void log_dependency(DepType dept, GrowableArray<ciBaseObject*>* args) {
375 ResourceMark rm;
376 int argslen = args->length();
377 write_dependency_to(log(), dept, args);
378 guarantee(argslen == args->length(),
379 "args array cannot grow inside nested ResoureMark scope");
380 }
381
382 void log_dependency(DepType dept,
383 ciBaseObject* x0,
384 ciBaseObject* x1 = nullptr,
385 ciBaseObject* x2 = nullptr,
386 ciBaseObject* x3 = nullptr) {
387 if (log() == nullptr) {
388 return;
389 }
390 ResourceMark rm;
391 GrowableArray<ciBaseObject*>* ciargs =
392 new GrowableArray<ciBaseObject*>(dep_args(dept));
393 assert (x0 != nullptr, "no log x0");
394 ciargs->push(x0);
395
396 if (x1 != nullptr) {
397 ciargs->push(x1);
398 }
399 if (x2 != nullptr) {
400 ciargs->push(x2);
401 }
402 if (x3 != nullptr) {
403 ciargs->push(x3);
404 }
405 assert(ciargs->length() == dep_args(dept), "");
406 log_dependency(dept, ciargs);
407 }
408
409 class DepArgument : public ResourceObj {
410 private:
411 bool _is_oop;
412 bool _valid;
413 void* _value;
414 public:
415 DepArgument() : _is_oop(false), _valid(false), _value(nullptr) {}
416 DepArgument(oop v): _is_oop(true), _valid(true), _value(v) {}
417 DepArgument(Metadata* v): _is_oop(false), _valid(true), _value(v) {}
418
419 bool is_null() const { return _value == nullptr; }
420 bool is_oop() const { return _is_oop; }
421 bool is_metadata() const { return !_is_oop; }
422 bool is_klass() const { return is_metadata() && metadata_value()->is_klass(); }
423 bool is_method() const { return is_metadata() && metadata_value()->is_method(); }
424
425 oop oop_value() const { assert(_is_oop && _valid, "must be"); return cast_to_oop(_value); }
426 Metadata* metadata_value() const { assert(!_is_oop && _valid, "must be"); return (Metadata*) _value; }
427 };
428
429 static void print_dependency(DepType dept,
430 GrowableArray<DepArgument>* args,
431 Klass* witness = nullptr, outputStream* st = tty);
432
433 private:
434 // helper for encoding common context types as zero:
435 static ciKlass* ctxk_encoded_as_null(DepType dept, ciBaseObject* x);
436
437 static Klass* ctxk_encoded_as_null(DepType dept, Metadata* x);
438
439 static void write_dependency_to(CompileLog* log,
440 DepType dept,
441 GrowableArray<ciBaseObject*>* args,
442 Klass* witness = nullptr);
443 static void write_dependency_to(CompileLog* log,
444 DepType dept,
445 GrowableArray<DepArgument>* args,
446 Klass* witness = nullptr);
447 static void write_dependency_to(xmlStream* xtty,
448 DepType dept,
449 GrowableArray<DepArgument>* args,
450 Klass* witness = nullptr);
451 public:
452 // Use this to iterate over an nmethod's dependency set.
453 // Works on new and old dependency sets.
454 // Usage:
455 //
456 // ;
457 // Dependencies::DepType dept;
458 // for (Dependencies::DepStream deps(nm); deps.next(); ) {
459 // ...
460 // }
461 //
462 // The caller must be in the VM, since oops are not wrapped in handles.
463 class DepStream {
464 private:
465 nmethod* _code; // null if in a compiler thread
466 Dependencies* _deps; // null if not in a compiler thread
467 CompressedReadStream _bytes;
468 #ifdef ASSERT
469 size_t _byte_limit;
470 #endif
471
472 // iteration variables:
473 DepType _type;
474 int _xi[max_arg_count+1];
475
476 void initial_asserts(size_t byte_limit) NOT_DEBUG({});
477
478 inline Metadata* recorded_metadata_at(int i);
479 inline oop recorded_oop_at(int i);
480
481 Klass* check_klass_dependency(KlassDepChange* changes);
482 Klass* check_new_klass_dependency(NewKlassDepChange* changes);
483 Klass* check_klass_init_dependency(KlassInitDepChange* changes);
484 Klass* check_call_site_dependency(CallSiteDepChange* changes);
485
486 void trace_and_log_witness(Klass* witness);
487
488 public:
489 DepStream(Dependencies* deps)
490 : _code(nullptr),
491 _deps(deps),
492 _bytes(deps->content_bytes())
493 {
494 initial_asserts(deps->size_in_bytes());
495 }
496 DepStream(nmethod* code)
497 : _code(code),
498 _deps(nullptr),
499 _bytes(code->dependencies_begin())
500 {
501 initial_asserts(code->dependencies_size());
502 }
503
504 bool next();
505
506 DepType type() { return _type; }
507 bool is_oop_argument(int i) { return type() == call_site_target_value; }
508 uintptr_t get_identifier(int i);
509
510 int argument_count() { return dep_args(type()); }
511 int argument_index(int i) { assert(0 <= i && i < argument_count(), "oob");
512 return _xi[i]; }
513 Metadata* argument(int i); // => recorded_oop_at(argument_index(i))
514 oop argument_oop(int i); // => recorded_oop_at(argument_index(i))
515 InstanceKlass* context_type();
516
517 bool is_klass_type() { return Dependencies::is_klass_type(type()); }
518
519 Method* method_argument(int i) {
520 Metadata* x = argument(i);
521 assert(x->is_method(), "type");
522 return (Method*) x;
523 }
524 Klass* type_argument(int i) {
525 Metadata* x = argument(i);
526 assert(x->is_klass(), "type");
527 return (Klass*) x;
528 }
529
530 // The point of the whole exercise: Is this dep still OK?
531 Klass* check_dependency() {
532 Klass* result = check_klass_dependency(nullptr);
533 if (result != nullptr) return result;
534 return check_call_site_dependency(nullptr);
535 }
536
537 // A lighter version: Checks only around recent changes in a class
538 // hierarchy. (See Universe::flush_dependents_on.)
539 Klass* spot_check_dependency_at(DepChange& changes);
540
541 // Log the current dependency to xtty or compilation log.
542 void log_dependency(Klass* witness = nullptr);
543
544 // Print the current dependency to tty.
545 void print_dependency(outputStream* st, Klass* witness = nullptr, bool verbose = false);
546 };
547 friend class Dependencies::DepStream;
548
549 NOT_PRODUCT(static void print_statistics();)
550 };
551
552
553 class DependencySignature : public ResourceObj {
554 private:
555 int _args_count;
556 uintptr_t _argument_hash[Dependencies::max_arg_count];
557 Dependencies::DepType _type;
558
559 public:
560 DependencySignature(Dependencies::DepStream& dep) {
561 _args_count = dep.argument_count();
562 _type = dep.type();
563 for (int i = 0; i < _args_count; i++) {
564 _argument_hash[i] = dep.get_identifier(i);
565 }
566 }
567
568 static bool equals(DependencySignature const& s1, DependencySignature const& s2);
569 static unsigned hash (DependencySignature const& s1) { return (unsigned)(s1.arg(0) >> 2); }
570
571 int args_count() const { return _args_count; }
572 uintptr_t arg(int idx) const { return _argument_hash[idx]; }
573 Dependencies::DepType type() const { return _type; }
574
575 };
576
577
578 // Every particular DepChange is a sub-class of this class.
579 class DepChange : public StackObj {
580 public:
581 // What kind of DepChange is this?
582 virtual bool is_klass_change() const { return false; }
583 virtual bool is_new_klass_change() const { return false; }
584 virtual bool is_klass_init_change() const { return false; }
585 virtual bool is_call_site_change() const { return false; }
586
587 // Subclass casting with assertions.
588 KlassDepChange* as_klass_change() {
589 assert(is_klass_change(), "bad cast");
590 return (KlassDepChange*) this;
591 }
592 NewKlassDepChange* as_new_klass_change() {
593 assert(is_new_klass_change(), "bad cast");
594 return (NewKlassDepChange*) this;
595 }
596 KlassInitDepChange* as_klass_init_change() {
597 assert(is_klass_init_change(), "bad cast");
598 return (KlassInitDepChange*) this;
599 }
600 CallSiteDepChange* as_call_site_change() {
601 assert(is_call_site_change(), "bad cast");
602 return (CallSiteDepChange*) this;
603 }
604
605 void print();
606 void print_on(outputStream* st);
607
608 public:
609 enum ChangeType {
610 NO_CHANGE = 0, // an uninvolved klass
611 Change_new_type, // a newly loaded type
612 Change_new_sub, // a super with a new subtype
613 Change_new_impl, // an interface with a new implementation
614 CHANGE_LIMIT,
615 Start_Klass = CHANGE_LIMIT // internal indicator for ContextStream
616 };
617
618 // Usage:
619 // for (DepChange::ContextStream str(changes); str.next(); ) {
620 // InstanceKlass* k = str.klass();
621 // switch (str.change_type()) {
622 // ...
623 // }
624 // }
625 class ContextStream : public StackObj {
626 private:
627 DepChange& _changes;
628 friend class DepChange;
629
630 // iteration variables:
631 ChangeType _change_type;
632 InstanceKlass* _klass;
633 Array<InstanceKlass*>* _ti_base; // i.e., transitive_interfaces
634 int _ti_index;
635 int _ti_limit;
636
637 // start at the beginning:
638 void start();
639
640 public:
641 ContextStream(DepChange& changes)
642 : _changes(changes)
643 { start(); }
644
645 ContextStream(DepChange& changes, NoSafepointVerifier& nsv)
646 : _changes(changes)
647 // the nsv argument makes it safe to hold oops like _klass
648 { start(); }
649
650 bool next();
651
652 ChangeType change_type() { return _change_type; }
653 InstanceKlass* klass() { return _klass; }
654 };
655 friend class DepChange::ContextStream;
656 };
657
658
659 // A class hierarchy change coming through the VM (under the Compile_lock).
660 // The change is structured as a single type with any number of supers
661 // and implemented interface types. Other than the type, any of the
662 // super types can be context types for a relevant dependency, which the
663 // type could invalidate.
664 class KlassDepChange : public DepChange {
665 private:
666 // each change set is rooted in exactly one type (at present):
667 InstanceKlass* _type;
668
669 void initialize();
670
671 protected:
672 // notes the type, marks it and all its super-types
673 KlassDepChange(InstanceKlass* type) : _type(type) {
674 initialize();
675 }
676
677 // cleans up the marks
678 ~KlassDepChange();
679
680 public:
681 // What kind of DepChange is this?
682 virtual bool is_klass_change() const { return true; }
683
684 InstanceKlass* type() { return _type; }
685
686 // involves_context(k) is true if k == _type or any of its super types
687 bool involves_context(Klass* k);
688 };
689
690 // A class hierarchy change: new type is loaded.
691 class NewKlassDepChange : public KlassDepChange {
692 public:
693 NewKlassDepChange(InstanceKlass* new_type) : KlassDepChange(new_type) {}
694
695 // What kind of DepChange is this?
696 virtual bool is_new_klass_change() const { return true; }
697
698 InstanceKlass* new_type() { return type(); }
699 };
700
701 // Change in initialization state of a loaded class.
702 class KlassInitDepChange : public KlassDepChange {
703 public:
704 KlassInitDepChange(InstanceKlass* type) : KlassDepChange(type) {}
705
706 // What kind of DepChange is this?
707 virtual bool is_klass_init_change() const { return true; }
708 };
709
710 // A CallSite has changed its target.
711 class CallSiteDepChange : public DepChange {
712 private:
713 Handle _call_site;
714 Handle _method_handle;
715
716 public:
717 CallSiteDepChange(Handle call_site, Handle method_handle);
718
719 // What kind of DepChange is this?
720 virtual bool is_call_site_change() const { return true; }
721
722 oop call_site() const { return _call_site(); }
723 oop method_handle() const { return _method_handle(); }
724 };
725
726 #endif // SHARE_CODE_DEPENDENCIES_HPP