1/*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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24
25#ifndef SHARE_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 "classfile/systemDictionary.hpp"
33#include "code/compressedStream.hpp"
34#include "code/nmethod.hpp"
35#include "memory/resourceArea.hpp"
36#include "runtime/safepointVerifiers.hpp"
37#include "utilities/growableArray.hpp"
38#include "utilities/hashtable.hpp"
39
40//** Dependencies represent assertions (approximate invariants) within
41// the runtime system, e.g. class hierarchy changes. An example is an
42// assertion that a given method is not overridden; another example is
43// that a type has only one concrete subtype. Compiled code which
44// relies on such assertions must be discarded if they are overturned
45// by changes in the runtime system. We can think of these assertions
46// as approximate invariants, because we expect them to be overturned
47// very infrequently. We are willing to perform expensive recovery
48// operations when they are overturned. The benefit, of course, is
49// performing optimistic optimizations (!) on the object code.
50//
51// Changes in the class hierarchy due to dynamic linking or
52// class evolution can violate dependencies. There is enough
53// indexing between classes and nmethods to make dependency
54// checking reasonably efficient.
55
56class ciEnv;
57class nmethod;
58class OopRecorder;
59class xmlStream;
60class CompileLog;
61class DepChange;
62class KlassDepChange;
63class CallSiteDepChange;
64class NoSafepointVerifier;
65
66class Dependencies: public ResourceObj {
67 public:
68 // Note: In the comments on dependency types, most uses of the terms
69 // subtype and supertype are used in a "non-strict" or "inclusive"
70 // sense, and are starred to remind the reader of this fact.
71 // Strict uses of the terms use the word "proper".
72 //
73 // Specifically, every class is its own subtype* and supertype*.
74 // (This trick is easier than continually saying things like "Y is a
75 // subtype of X or X itself".)
76 //
77 // Sometimes we write X > Y to mean X is a proper supertype of Y.
78 // The notation X > {Y, Z} means X has proper subtypes Y, Z.
79 // The notation X.m > Y means that Y inherits m from X, while
80 // X.m > Y.m means Y overrides X.m. A star denotes abstractness,
81 // as *I > A, meaning (abstract) interface I is a super type of A,
82 // or A.*m > B.m, meaning B.m implements abstract method A.m.
83 //
84 // In this module, the terms "subtype" and "supertype" refer to
85 // Java-level reference type conversions, as detected by
86 // "instanceof" and performed by "checkcast" operations. The method
87 // Klass::is_subtype_of tests these relations. Note that "subtype"
88 // is richer than "subclass" (as tested by Klass::is_subclass_of),
89 // since it takes account of relations involving interface and array
90 // types.
91 //
92 // To avoid needless complexity, dependencies involving array types
93 // are not accepted. If you need to make an assertion about an
94 // array type, make the assertion about its corresponding element
95 // types. Any assertion that might change about an array type can
96 // be converted to an assertion about its element type.
97 //
98 // Most dependencies are evaluated over a "context type" CX, which
99 // stands for the set Subtypes(CX) of every Java type that is a subtype*
100 // of CX. When the system loads a new class or interface N, it is
101 // responsible for re-evaluating changed dependencies whose context
102 // type now includes N, that is, all super types of N.
103 //
104 enum DepType {
105 end_marker = 0,
106
107 // An 'evol' dependency simply notes that the contents of the
108 // method were used. If it evolves (is replaced), the nmethod
109 // must be recompiled. No other dependencies are implied.
110 evol_method,
111 FIRST_TYPE = evol_method,
112
113 // A context type CX is a leaf it if has no proper subtype.
114 leaf_type,
115
116 // An abstract class CX has exactly one concrete subtype CC.
117 abstract_with_unique_concrete_subtype,
118
119 // The type CX is purely abstract, with no concrete subtype* at all.
120 abstract_with_no_concrete_subtype,
121
122 // The concrete CX is free of concrete proper subtypes.
123 concrete_with_no_concrete_subtype,
124
125 // Given a method M1 and a context class CX, the set MM(CX, M1) of
126 // "concrete matching methods" in CX of M1 is the set of every
127 // concrete M2 for which it is possible to create an invokevirtual
128 // or invokeinterface call site that can reach either M1 or M2.
129 // That is, M1 and M2 share a name, signature, and vtable index.
130 // We wish to notice when the set MM(CX, M1) is just {M1}, or
131 // perhaps a set of two {M1,M2}, and issue dependencies on this.
132
133 // The set MM(CX, M1) can be computed by starting with any matching
134 // concrete M2 that is inherited into CX, and then walking the
135 // subtypes* of CX looking for concrete definitions.
136
137 // The parameters to this dependency are the method M1 and the
138 // context class CX. M1 must be either inherited in CX or defined
139 // in a subtype* of CX. It asserts that MM(CX, M1) is no greater
140 // than {M1}.
141 unique_concrete_method, // one unique concrete method under CX
142
143 // An "exclusive" assertion concerns two methods or subtypes, and
144 // declares that there are at most two (or perhaps later N>2)
145 // specific items that jointly satisfy the restriction.
146 // We list all items explicitly rather than just giving their
147 // count, for robustness in the face of complex schema changes.
148
149 // A context class CX (which may be either abstract or concrete)
150 // has two exclusive concrete subtypes* C1, C2 if every concrete
151 // subtype* of CX is either C1 or C2. Note that if neither C1 or C2
152 // are equal to CX, then CX itself must be abstract. But it is
153 // also possible (for example) that C1 is CX (a concrete class)
154 // and C2 is a proper subtype of C1.
155 abstract_with_exclusive_concrete_subtypes_2,
156
157 // This dependency asserts that MM(CX, M1) is no greater than {M1,M2}.
158 exclusive_concrete_methods_2,
159
160 // This dependency asserts that no instances of class or it's
161 // subclasses require finalization registration.
162 no_finalizable_subclasses,
163
164 // This dependency asserts when the CallSite.target value changed.
165 call_site_target_value,
166
167 TYPE_LIMIT
168 };
169 enum {
170 LG2_TYPE_LIMIT = 4, // assert(TYPE_LIMIT <= (1<<LG2_TYPE_LIMIT))
171
172 // handy categorizations of dependency types:
173 all_types = ((1 << TYPE_LIMIT) - 1) & ((~0u) << FIRST_TYPE),
174
175 non_klass_types = (1 << call_site_target_value),
176 klass_types = all_types & ~non_klass_types,
177
178 non_ctxk_types = (1 << evol_method) | (1 << call_site_target_value),
179 implicit_ctxk_types = 0,
180 explicit_ctxk_types = all_types & ~(non_ctxk_types | implicit_ctxk_types),
181
182 max_arg_count = 3, // current maximum number of arguments (incl. ctxk)
183
184 // A "context type" is a class or interface that
185 // provides context for evaluating a dependency.
186 // When present, it is one of the arguments (dep_context_arg).
187 //
188 // If a dependency does not have a context type, there is a
189 // default context, depending on the type of the dependency.
190 // This bit signals that a default context has been compressed away.
191 default_context_type_bit = (1<<LG2_TYPE_LIMIT)
192 };
193
194 static const char* dep_name(DepType dept);
195 static int dep_args(DepType dept);
196
197 static bool is_klass_type( DepType dept) { return dept_in_mask(dept, klass_types ); }
198
199 static bool has_explicit_context_arg(DepType dept) { return dept_in_mask(dept, explicit_ctxk_types); }
200 static bool has_implicit_context_arg(DepType dept) { return dept_in_mask(dept, implicit_ctxk_types); }
201
202 static int dep_context_arg(DepType dept) { return has_explicit_context_arg(dept) ? 0 : -1; }
203 static int dep_implicit_context_arg(DepType dept) { return has_implicit_context_arg(dept) ? 0 : -1; }
204
205 static void check_valid_dependency_type(DepType dept);
206
207#if INCLUDE_JVMCI
208 // A Metadata* or object value recorded in an OopRecorder
209 class DepValue {
210 private:
211 // Unique identifier of the value within the associated OopRecorder that
212 // encodes both the category of the value (0: invalid, positive: metadata, negative: object)
213 // and the index within a category specific array (metadata: index + 1, object: -(index + 1))
214 int _id;
215
216 public:
217 DepValue() : _id(0) {}
218 DepValue(OopRecorder* rec, Metadata* metadata, DepValue* candidate = NULL) {
219 assert(candidate == NULL || candidate->is_metadata(), "oops");
220 if (candidate != NULL && candidate->as_metadata(rec) == metadata) {
221 _id = candidate->_id;
222 } else {
223 _id = rec->find_index(metadata) + 1;
224 }
225 }
226 DepValue(OopRecorder* rec, jobject obj, DepValue* candidate = NULL) {
227 assert(candidate == NULL || candidate->is_object(), "oops");
228 if (candidate != NULL && candidate->as_object(rec) == obj) {
229 _id = candidate->_id;
230 } else {
231 _id = -(rec->find_index(obj) + 1);
232 }
233 }
234
235 // Used to sort values in ascending order of index() with metadata values preceding object values
236 int sort_key() const { return -_id; }
237
238 bool operator == (const DepValue& other) const { return other._id == _id; }
239
240 bool is_valid() const { return _id != 0; }
241 int index() const { assert(is_valid(), "oops"); return _id < 0 ? -(_id + 1) : _id - 1; }
242 bool is_metadata() const { assert(is_valid(), "oops"); return _id > 0; }
243 bool is_object() const { assert(is_valid(), "oops"); return _id < 0; }
244
245 Metadata* as_metadata(OopRecorder* rec) const { assert(is_metadata(), "oops"); return rec->metadata_at(index()); }
246 Klass* as_klass(OopRecorder* rec) const {
247 Metadata* m = as_metadata(rec);
248 assert(m != NULL, "as_metadata returned NULL");
249 assert(m->is_klass(), "oops");
250 return (Klass*) m;
251 }
252 Method* as_method(OopRecorder* rec) const {
253 Metadata* m = as_metadata(rec);
254 assert(m != NULL, "as_metadata returned NULL");
255 assert(m->is_method(), "oops");
256 return (Method*) m;
257 }
258 jobject as_object(OopRecorder* rec) const { assert(is_object(), "oops"); return rec->oop_at(index()); }
259 };
260#endif // INCLUDE_JVMCI
261
262 private:
263 // State for writing a new set of dependencies:
264 GrowableArray<int>* _dep_seen; // (seen[h->ident] & (1<<dept))
265 GrowableArray<ciBaseObject*>* _deps[TYPE_LIMIT];
266#if INCLUDE_JVMCI
267 bool _using_dep_values;
268 GrowableArray<DepValue>* _dep_values[TYPE_LIMIT];
269#endif
270
271 static const char* _dep_name[TYPE_LIMIT];
272 static int _dep_args[TYPE_LIMIT];
273
274 static bool dept_in_mask(DepType dept, int mask) {
275 return (int)dept >= 0 && dept < TYPE_LIMIT && ((1<<dept) & mask) != 0;
276 }
277
278 bool note_dep_seen(int dept, ciBaseObject* x) {
279 assert(dept < BitsPerInt, "oob");
280 int x_id = x->ident();
281 assert(_dep_seen != NULL, "deps must be writable");
282 int seen = _dep_seen->at_grow(x_id, 0);
283 _dep_seen->at_put(x_id, seen | (1<<dept));
284 // return true if we've already seen dept/x
285 return (seen & (1<<dept)) != 0;
286 }
287
288#if INCLUDE_JVMCI
289 bool note_dep_seen(int dept, DepValue x) {
290 assert(dept < BitsPerInt, "oops");
291 // place metadata deps at even indexes, object deps at odd indexes
292 int x_id = x.is_metadata() ? x.index() * 2 : (x.index() * 2) + 1;
293 assert(_dep_seen != NULL, "deps must be writable");
294 int seen = _dep_seen->at_grow(x_id, 0);
295 _dep_seen->at_put(x_id, seen | (1<<dept));
296 // return true if we've already seen dept/x
297 return (seen & (1<<dept)) != 0;
298 }
299#endif
300
301 bool maybe_merge_ctxk(GrowableArray<ciBaseObject*>* deps,
302 int ctxk_i, ciKlass* ctxk);
303#if INCLUDE_JVMCI
304 bool maybe_merge_ctxk(GrowableArray<DepValue>* deps,
305 int ctxk_i, DepValue ctxk);
306#endif
307
308 void sort_all_deps();
309 size_t estimate_size_in_bytes();
310
311 // Initialize _deps, etc.
312 void initialize(ciEnv* env);
313
314 // State for making a new set of dependencies:
315 OopRecorder* _oop_recorder;
316
317 // Logging support
318 CompileLog* _log;
319
320 address _content_bytes; // everything but the oop references, encoded
321 size_t _size_in_bytes;
322
323 public:
324 // Make a new empty dependencies set.
325 Dependencies(ciEnv* env) {
326 initialize(env);
327 }
328#if INCLUDE_JVMCI
329 Dependencies(Arena* arena, OopRecorder* oop_recorder, CompileLog* log);
330#endif
331
332 private:
333 // Check for a valid context type.
334 // Enforce the restriction against array types.
335 static void check_ctxk(ciKlass* ctxk) {
336 assert(ctxk->is_instance_klass(), "java types only");
337 }
338 static void check_ctxk_concrete(ciKlass* ctxk) {
339 assert(is_concrete_klass(ctxk->as_instance_klass()), "must be concrete");
340 }
341 static void check_ctxk_abstract(ciKlass* ctxk) {
342 check_ctxk(ctxk);
343 assert(!is_concrete_klass(ctxk->as_instance_klass()), "must be abstract");
344 }
345 static void check_unique_method(ciKlass* ctxk, ciMethod* m) {
346 assert(!m->can_be_statically_bound(ctxk->as_instance_klass()), "redundant");
347 }
348
349 void assert_common_1(DepType dept, ciBaseObject* x);
350 void assert_common_2(DepType dept, ciBaseObject* x0, ciBaseObject* x1);
351 void assert_common_3(DepType dept, ciKlass* ctxk, ciBaseObject* x1, ciBaseObject* x2);
352
353 public:
354 // Adding assertions to a new dependency set at compile time:
355 void assert_evol_method(ciMethod* m);
356 void assert_leaf_type(ciKlass* ctxk);
357 void assert_abstract_with_unique_concrete_subtype(ciKlass* ctxk, ciKlass* conck);
358 void assert_abstract_with_no_concrete_subtype(ciKlass* ctxk);
359 void assert_concrete_with_no_concrete_subtype(ciKlass* ctxk);
360 void assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm);
361 void assert_abstract_with_exclusive_concrete_subtypes(ciKlass* ctxk, ciKlass* k1, ciKlass* k2);
362 void assert_exclusive_concrete_methods(ciKlass* ctxk, ciMethod* m1, ciMethod* m2);
363 void assert_has_no_finalizable_subclasses(ciKlass* ctxk);
364 void assert_call_site_target_value(ciCallSite* call_site, ciMethodHandle* method_handle);
365
366#if INCLUDE_JVMCI
367 private:
368 static void check_ctxk(Klass* ctxk) {
369 assert(ctxk->is_instance_klass(), "java types only");
370 }
371 static void check_ctxk_abstract(Klass* ctxk) {
372 check_ctxk(ctxk);
373 assert(ctxk->is_abstract(), "must be abstract");
374 }
375 static void check_unique_method(Klass* ctxk, Method* m) {
376 assert(!m->can_be_statically_bound(InstanceKlass::cast(ctxk)), "redundant");
377 }
378
379 void assert_common_1(DepType dept, DepValue x);
380 void assert_common_2(DepType dept, DepValue x0, DepValue x1);
381
382 public:
383 void assert_evol_method(Method* m);
384 void assert_has_no_finalizable_subclasses(Klass* ctxk);
385 void assert_leaf_type(Klass* ctxk);
386 void assert_unique_concrete_method(Klass* ctxk, Method* uniqm);
387 void assert_abstract_with_unique_concrete_subtype(Klass* ctxk, Klass* conck);
388 void assert_call_site_target_value(oop callSite, oop methodHandle);
389#endif // INCLUDE_JVMCI
390
391 // Define whether a given method or type is concrete.
392 // These methods define the term "concrete" as used in this module.
393 // For this module, an "abstract" class is one which is non-concrete.
394 //
395 // Future optimizations may allow some classes to remain
396 // non-concrete until their first instantiation, and allow some
397 // methods to remain non-concrete until their first invocation.
398 // In that case, there would be a middle ground between concrete
399 // and abstract (as defined by the Java language and VM).
400 static bool is_concrete_klass(Klass* k); // k is instantiable
401 static bool is_concrete_method(Method* m, Klass* k); // m is invocable
402 static Klass* find_finalizable_subclass(Klass* k);
403
404 // These versions of the concreteness queries work through the CI.
405 // The CI versions are allowed to skew sometimes from the VM
406 // (oop-based) versions. The cost of such a difference is a
407 // (safely) aborted compilation, or a deoptimization, or a missed
408 // optimization opportunity.
409 //
410 // In order to prevent spurious assertions, query results must
411 // remain stable within any single ciEnv instance. (I.e., they must
412 // not go back into the VM to get their value; they must cache the
413 // bit in the CI, either eagerly or lazily.)
414 static bool is_concrete_klass(ciInstanceKlass* k); // k appears instantiable
415 static bool has_finalizable_subclass(ciInstanceKlass* k);
416
417 // As a general rule, it is OK to compile under the assumption that
418 // a given type or method is concrete, even if it at some future
419 // point becomes abstract. So dependency checking is one-sided, in
420 // that it permits supposedly concrete classes or methods to turn up
421 // as really abstract. (This shouldn't happen, except during class
422 // evolution, but that's the logic of the checking.) However, if a
423 // supposedly abstract class or method suddenly becomes concrete, a
424 // dependency on it must fail.
425
426 // Checking old assertions at run-time (in the VM only):
427 static Klass* check_evol_method(Method* m);
428 static Klass* check_leaf_type(Klass* ctxk);
429 static Klass* check_abstract_with_unique_concrete_subtype(Klass* ctxk, Klass* conck,
430 KlassDepChange* changes = NULL);
431 static Klass* check_abstract_with_no_concrete_subtype(Klass* ctxk,
432 KlassDepChange* changes = NULL);
433 static Klass* check_concrete_with_no_concrete_subtype(Klass* ctxk,
434 KlassDepChange* changes = NULL);
435 static Klass* check_unique_concrete_method(Klass* ctxk, Method* uniqm,
436 KlassDepChange* changes = NULL);
437 static Klass* check_abstract_with_exclusive_concrete_subtypes(Klass* ctxk, Klass* k1, Klass* k2,
438 KlassDepChange* changes = NULL);
439 static Klass* check_exclusive_concrete_methods(Klass* ctxk, Method* m1, Method* m2,
440 KlassDepChange* changes = NULL);
441 static Klass* check_has_no_finalizable_subclasses(Klass* ctxk, KlassDepChange* changes = NULL);
442 static Klass* check_call_site_target_value(oop call_site, oop method_handle, CallSiteDepChange* changes = NULL);
443 // A returned Klass* is NULL if the dependency assertion is still
444 // valid. A non-NULL Klass* is a 'witness' to the assertion
445 // failure, a point in the class hierarchy where the assertion has
446 // been proven false. For example, if check_leaf_type returns
447 // non-NULL, the value is a subtype of the supposed leaf type. This
448 // witness value may be useful for logging the dependency failure.
449 // Note that, when a dependency fails, there may be several possible
450 // witnesses to the failure. The value returned from the check_foo
451 // method is chosen arbitrarily.
452
453 // The 'changes' value, if non-null, requests a limited spot-check
454 // near the indicated recent changes in the class hierarchy.
455 // It is used by DepStream::spot_check_dependency_at.
456
457 // Detecting possible new assertions:
458 static Klass* find_unique_concrete_subtype(Klass* ctxk);
459 static Method* find_unique_concrete_method(Klass* ctxk, Method* m);
460 static int find_exclusive_concrete_subtypes(Klass* ctxk, int klen, Klass* k[]);
461
462 // Create the encoding which will be stored in an nmethod.
463 void encode_content_bytes();
464
465 address content_bytes() {
466 assert(_content_bytes != NULL, "encode it first");
467 return _content_bytes;
468 }
469 size_t size_in_bytes() {
470 assert(_content_bytes != NULL, "encode it first");
471 return _size_in_bytes;
472 }
473
474 OopRecorder* oop_recorder() { return _oop_recorder; }
475 CompileLog* log() { return _log; }
476
477 void copy_to(nmethod* nm);
478
479 DepType validate_dependencies(CompileTask* task, bool counter_changed, char** failure_detail = NULL);
480
481 void log_all_dependencies();
482
483 void log_dependency(DepType dept, GrowableArray<ciBaseObject*>* args) {
484 ResourceMark rm;
485 int argslen = args->length();
486 write_dependency_to(log(), dept, args);
487 guarantee(argslen == args->length(),
488 "args array cannot grow inside nested ResoureMark scope");
489 }
490
491 void log_dependency(DepType dept,
492 ciBaseObject* x0,
493 ciBaseObject* x1 = NULL,
494 ciBaseObject* x2 = NULL) {
495 if (log() == NULL) {
496 return;
497 }
498 ResourceMark rm;
499 GrowableArray<ciBaseObject*>* ciargs =
500 new GrowableArray<ciBaseObject*>(dep_args(dept));
501 assert (x0 != NULL, "no log x0");
502 ciargs->push(x0);
503
504 if (x1 != NULL) {
505 ciargs->push(x1);
506 }
507 if (x2 != NULL) {
508 ciargs->push(x2);
509 }
510 assert(ciargs->length() == dep_args(dept), "");
511 log_dependency(dept, ciargs);
512 }
513
514 class DepArgument : public ResourceObj {
515 private:
516 bool _is_oop;
517 bool _valid;
518 void* _value;
519 public:
520 DepArgument() : _is_oop(false), _valid(false), _value(NULL) {}
521 DepArgument(oop v): _is_oop(true), _valid(true), _value(v) {}
522 DepArgument(Metadata* v): _is_oop(false), _valid(true), _value(v) {}
523
524 bool is_null() const { return _value == NULL; }
525 bool is_oop() const { return _is_oop; }
526 bool is_metadata() const { return !_is_oop; }
527 bool is_klass() const { return is_metadata() && metadata_value()->is_klass(); }
528 bool is_method() const { return is_metadata() && metadata_value()->is_method(); }
529
530 oop oop_value() const { assert(_is_oop && _valid, "must be"); return (oop) _value; }
531 Metadata* metadata_value() const { assert(!_is_oop && _valid, "must be"); return (Metadata*) _value; }
532 };
533
534 static void print_dependency(DepType dept,
535 GrowableArray<DepArgument>* args,
536 Klass* witness = NULL, outputStream* st = tty);
537
538 private:
539 // helper for encoding common context types as zero:
540 static ciKlass* ctxk_encoded_as_null(DepType dept, ciBaseObject* x);
541
542 static Klass* ctxk_encoded_as_null(DepType dept, Metadata* x);
543
544 static void write_dependency_to(CompileLog* log,
545 DepType dept,
546 GrowableArray<ciBaseObject*>* args,
547 Klass* witness = NULL);
548 static void write_dependency_to(CompileLog* log,
549 DepType dept,
550 GrowableArray<DepArgument>* args,
551 Klass* witness = NULL);
552 static void write_dependency_to(xmlStream* xtty,
553 DepType dept,
554 GrowableArray<DepArgument>* args,
555 Klass* witness = NULL);
556 public:
557 // Use this to iterate over an nmethod's dependency set.
558 // Works on new and old dependency sets.
559 // Usage:
560 //
561 // ;
562 // Dependencies::DepType dept;
563 // for (Dependencies::DepStream deps(nm); deps.next(); ) {
564 // ...
565 // }
566 //
567 // The caller must be in the VM, since oops are not wrapped in handles.
568 class DepStream {
569 private:
570 nmethod* _code; // null if in a compiler thread
571 Dependencies* _deps; // null if not in a compiler thread
572 CompressedReadStream _bytes;
573#ifdef ASSERT
574 size_t _byte_limit;
575#endif
576
577 // iteration variables:
578 DepType _type;
579 int _xi[max_arg_count+1];
580
581 void initial_asserts(size_t byte_limit) NOT_DEBUG({});
582
583 inline Metadata* recorded_metadata_at(int i);
584 inline oop recorded_oop_at(int i);
585
586 Klass* check_klass_dependency(KlassDepChange* changes);
587 Klass* check_call_site_dependency(CallSiteDepChange* changes);
588
589 void trace_and_log_witness(Klass* witness);
590
591 public:
592 DepStream(Dependencies* deps)
593 : _code(NULL),
594 _deps(deps),
595 _bytes(deps->content_bytes())
596 {
597 initial_asserts(deps->size_in_bytes());
598 }
599 DepStream(nmethod* code)
600 : _code(code),
601 _deps(NULL),
602 _bytes(code->dependencies_begin())
603 {
604 initial_asserts(code->dependencies_size());
605 }
606
607 bool next();
608
609 DepType type() { return _type; }
610 bool is_oop_argument(int i) { return type() == call_site_target_value; }
611 uintptr_t get_identifier(int i);
612
613 int argument_count() { return dep_args(type()); }
614 int argument_index(int i) { assert(0 <= i && i < argument_count(), "oob");
615 return _xi[i]; }
616 Metadata* argument(int i); // => recorded_oop_at(argument_index(i))
617 oop argument_oop(int i); // => recorded_oop_at(argument_index(i))
618 Klass* context_type();
619
620 bool is_klass_type() { return Dependencies::is_klass_type(type()); }
621
622 Method* method_argument(int i) {
623 Metadata* x = argument(i);
624 assert(x->is_method(), "type");
625 return (Method*) x;
626 }
627 Klass* type_argument(int i) {
628 Metadata* x = argument(i);
629 assert(x->is_klass(), "type");
630 return (Klass*) x;
631 }
632
633 // The point of the whole exercise: Is this dep still OK?
634 Klass* check_dependency() {
635 Klass* result = check_klass_dependency(NULL);
636 if (result != NULL) return result;
637 return check_call_site_dependency(NULL);
638 }
639
640 // A lighter version: Checks only around recent changes in a class
641 // hierarchy. (See Universe::flush_dependents_on.)
642 Klass* spot_check_dependency_at(DepChange& changes);
643
644 // Log the current dependency to xtty or compilation log.
645 void log_dependency(Klass* witness = NULL);
646
647 // Print the current dependency to tty.
648 void print_dependency(Klass* witness = NULL, bool verbose = false, outputStream* st = tty);
649 };
650 friend class Dependencies::DepStream;
651
652 static void print_statistics() PRODUCT_RETURN;
653};
654
655
656class DependencySignature : public ResourceObj {
657 private:
658 int _args_count;
659 uintptr_t _argument_hash[Dependencies::max_arg_count];
660 Dependencies::DepType _type;
661
662 public:
663 DependencySignature(Dependencies::DepStream& dep) {
664 _args_count = dep.argument_count();
665 _type = dep.type();
666 for (int i = 0; i < _args_count; i++) {
667 _argument_hash[i] = dep.get_identifier(i);
668 }
669 }
670
671 static bool equals(DependencySignature const& s1, DependencySignature const& s2);
672 static unsigned hash (DependencySignature const& s1) { return s1.arg(0) >> 2; }
673
674 int args_count() const { return _args_count; }
675 uintptr_t arg(int idx) const { return _argument_hash[idx]; }
676 Dependencies::DepType type() const { return _type; }
677
678};
679
680
681// Every particular DepChange is a sub-class of this class.
682class DepChange : public StackObj {
683 public:
684 // What kind of DepChange is this?
685 virtual bool is_klass_change() const { return false; }
686 virtual bool is_call_site_change() const { return false; }
687
688 virtual void mark_for_deoptimization(nmethod* nm) = 0;
689
690 // Subclass casting with assertions.
691 KlassDepChange* as_klass_change() {
692 assert(is_klass_change(), "bad cast");
693 return (KlassDepChange*) this;
694 }
695 CallSiteDepChange* as_call_site_change() {
696 assert(is_call_site_change(), "bad cast");
697 return (CallSiteDepChange*) this;
698 }
699
700 void print();
701
702 public:
703 enum ChangeType {
704 NO_CHANGE = 0, // an uninvolved klass
705 Change_new_type, // a newly loaded type
706 Change_new_sub, // a super with a new subtype
707 Change_new_impl, // an interface with a new implementation
708 CHANGE_LIMIT,
709 Start_Klass = CHANGE_LIMIT // internal indicator for ContextStream
710 };
711
712 // Usage:
713 // for (DepChange::ContextStream str(changes); str.next(); ) {
714 // Klass* k = str.klass();
715 // switch (str.change_type()) {
716 // ...
717 // }
718 // }
719 class ContextStream : public StackObj {
720 private:
721 DepChange& _changes;
722 friend class DepChange;
723
724 // iteration variables:
725 ChangeType _change_type;
726 Klass* _klass;
727 Array<InstanceKlass*>* _ti_base; // i.e., transitive_interfaces
728 int _ti_index;
729 int _ti_limit;
730
731 // start at the beginning:
732 void start();
733
734 public:
735 ContextStream(DepChange& changes)
736 : _changes(changes)
737 { start(); }
738
739 ContextStream(DepChange& changes, NoSafepointVerifier& nsv)
740 : _changes(changes)
741 // the nsv argument makes it safe to hold oops like _klass
742 { start(); }
743
744 bool next();
745
746 ChangeType change_type() { return _change_type; }
747 Klass* klass() { return _klass; }
748 };
749 friend class DepChange::ContextStream;
750};
751
752
753// A class hierarchy change coming through the VM (under the Compile_lock).
754// The change is structured as a single new type with any number of supers
755// and implemented interface types. Other than the new type, any of the
756// super types can be context types for a relevant dependency, which the
757// new type could invalidate.
758class KlassDepChange : public DepChange {
759 private:
760 // each change set is rooted in exactly one new type (at present):
761 Klass* _new_type;
762
763 void initialize();
764
765 public:
766 // notes the new type, marks it and all its super-types
767 KlassDepChange(Klass* new_type)
768 : _new_type(new_type)
769 {
770 initialize();
771 }
772
773 // cleans up the marks
774 ~KlassDepChange();
775
776 // What kind of DepChange is this?
777 virtual bool is_klass_change() const { return true; }
778
779 virtual void mark_for_deoptimization(nmethod* nm) {
780 nm->mark_for_deoptimization(/*inc_recompile_counts=*/true);
781 }
782
783 Klass* new_type() { return _new_type; }
784
785 // involves_context(k) is true if k is new_type or any of the super types
786 bool involves_context(Klass* k);
787};
788
789
790// A CallSite has changed its target.
791class CallSiteDepChange : public DepChange {
792 private:
793 Handle _call_site;
794 Handle _method_handle;
795
796 public:
797 CallSiteDepChange(Handle call_site, Handle method_handle);
798
799 // What kind of DepChange is this?
800 virtual bool is_call_site_change() const { return true; }
801
802 virtual void mark_for_deoptimization(nmethod* nm) {
803 nm->mark_for_deoptimization(/*inc_recompile_counts=*/false);
804 }
805
806 oop call_site() const { return _call_site(); }
807 oop method_handle() const { return _method_handle(); }
808};
809
810#endif // SHARE_CODE_DEPENDENCIES_HPP
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