1 /*
2 * Copyright (c) 2005, 2023, 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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7 * published by the Free Software Foundation.
8 *
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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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16 * 2 along with this work; if not, write to the Free Software Foundation,
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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 end_marker = 0,
107
108 // An 'evol' dependency simply notes that the contents of the
109 // method were used. If it evolves (is replaced), the nmethod
110 // must be recompiled. No other dependencies are implied.
111 evol_method,
112 FIRST_TYPE = evol_method,
113
114 // A context type CX is a leaf it if has no proper subtype.
115 leaf_type,
116
117 // An abstract class CX has exactly one concrete subtype CC.
118 abstract_with_unique_concrete_subtype,
119
120 // Given a method M1 and a context class CX, the set MM(CX, M1) of
121 // "concrete matching methods" in CX of M1 is the set of every
122 // concrete M2 for which it is possible to create an invokevirtual
123 // or invokeinterface call site that can reach either M1 or M2.
124 // That is, M1 and M2 share a name, signature, and vtable index.
125 // We wish to notice when the set MM(CX, M1) is just {M1}, or
126 // perhaps a set of two {M1,M2}, and issue dependencies on this.
127
128 // The set MM(CX, M1) can be computed by starting with any matching
129 // concrete M2 that is inherited into CX, and then walking the
130 // subtypes* of CX looking for concrete definitions.
131
132 // The parameters to this dependency are the method M1 and the
133 // context class CX. M1 must be either inherited in CX or defined
134 // in a subtype* of CX. It asserts that MM(CX, M1) is no greater
135 // than {M1}.
136 unique_concrete_method_2, // one unique concrete method under CX
137
138 // In addition to the method M1 and the context class CX, the parameters
139 // to this dependency are the resolved class RC1 and the
140 // resolved method RM1. It asserts that MM(CX, M1, RC1, RM1)
141 // is no greater than {M1}. RC1 and RM1 are used to improve the precision
142 // of the analysis.
143 unique_concrete_method_4, // one unique concrete method under CX
144
145 // This dependency asserts that interface CX has a unique implementor class.
146 unique_implementor, // one unique implementor under CX
147
148 // This dependency asserts that no instances of class or it's
149 // subclasses require finalization registration.
150 no_finalizable_subclasses,
151
152 // This dependency asserts when the CallSite.target value changed.
153 call_site_target_value,
154
155 TYPE_LIMIT
156 };
157 enum {
158 LG2_TYPE_LIMIT = 4, // assert(TYPE_LIMIT <= (1<<LG2_TYPE_LIMIT))
159
160 // handy categorizations of dependency types:
161 all_types = ((1 << TYPE_LIMIT) - 1) & ((~0u) << FIRST_TYPE),
162
163 non_klass_types = (1 << call_site_target_value),
164 klass_types = all_types & ~non_klass_types,
165
166 non_ctxk_types = (1 << evol_method) | (1 << call_site_target_value),
167 implicit_ctxk_types = 0,
168 explicit_ctxk_types = all_types & ~(non_ctxk_types | implicit_ctxk_types),
169
170 max_arg_count = 4, // current maximum number of arguments (incl. ctxk)
171
172 // A "context type" is a class or interface that
173 // provides context for evaluating a dependency.
174 // When present, it is one of the arguments (dep_context_arg).
175 //
176 // If a dependency does not have a context type, there is a
177 // default context, depending on the type of the dependency.
178 // This bit signals that a default context has been compressed away.
179 default_context_type_bit = (1<<LG2_TYPE_LIMIT)
180 };
181
182 static const char* dep_name(DepType dept);
183 static int dep_args(DepType dept);
184
185 static bool is_klass_type( DepType dept) { return dept_in_mask(dept, klass_types ); }
186
187 static bool has_explicit_context_arg(DepType dept) { return dept_in_mask(dept, explicit_ctxk_types); }
188 static bool has_implicit_context_arg(DepType dept) { return dept_in_mask(dept, implicit_ctxk_types); }
189
190 static int dep_context_arg(DepType dept) { return has_explicit_context_arg(dept) ? 0 : -1; }
191 static int dep_implicit_context_arg(DepType dept) { return has_implicit_context_arg(dept) ? 0 : -1; }
192
193 static void check_valid_dependency_type(DepType dept);
194
195 #if INCLUDE_JVMCI
196 // A Metadata* or object value recorded in an OopRecorder
197 class DepValue {
198 private:
199 // Unique identifier of the value within the associated OopRecorder that
200 // encodes both the category of the value (0: invalid, positive: metadata, negative: object)
201 // and the index within a category specific array (metadata: index + 1, object: -(index + 1))
202 int _id;
203
204 public:
205 DepValue() : _id(0) {}
206 DepValue(OopRecorder* rec, Metadata* metadata, DepValue* candidate = nullptr) {
207 assert(candidate == nullptr || candidate->is_metadata(), "oops");
208 if (candidate != nullptr && candidate->as_metadata(rec) == metadata) {
209 _id = candidate->_id;
210 } else {
211 _id = rec->find_index(metadata) + 1;
212 }
213 }
214 DepValue(OopRecorder* rec, jobject obj, DepValue* candidate = nullptr) {
215 assert(candidate == nullptr || candidate->is_object(), "oops");
216 if (candidate != nullptr && candidate->as_object(rec) == obj) {
217 _id = candidate->_id;
218 } else {
219 _id = -(rec->find_index(obj) + 1);
220 }
221 }
222
223 // Used to sort values in ascending order of index() with metadata values preceding object values
224 int sort_key() const { return -_id; }
225
226 bool operator == (const DepValue& other) const { return other._id == _id; }
227
228 bool is_valid() const { return _id != 0; }
229 int index() const { assert(is_valid(), "oops"); return _id < 0 ? -(_id + 1) : _id - 1; }
230 bool is_metadata() const { assert(is_valid(), "oops"); return _id > 0; }
231 bool is_object() const { assert(is_valid(), "oops"); return _id < 0; }
232
233 Metadata* as_metadata(OopRecorder* rec) const { assert(is_metadata(), "oops"); return rec->metadata_at(index()); }
234 Klass* as_klass(OopRecorder* rec) const {
235 Metadata* m = as_metadata(rec);
236 assert(m != nullptr, "as_metadata returned nullptr");
237 assert(m->is_klass(), "oops");
238 return (Klass*) m;
239 }
240 Method* as_method(OopRecorder* rec) const {
241 Metadata* m = as_metadata(rec);
242 assert(m != nullptr, "as_metadata returned nullptr");
243 assert(m->is_method(), "oops");
244 return (Method*) m;
245 }
246 jobject as_object(OopRecorder* rec) const { assert(is_object(), "oops"); return rec->oop_at(index()); }
247 };
248 #endif // INCLUDE_JVMCI
249
250 private:
251 // State for writing a new set of dependencies:
252 GrowableArray<int>* _dep_seen; // (seen[h->ident] & (1<<dept))
253 GrowableArray<ciBaseObject*>* _deps[TYPE_LIMIT];
254 #if INCLUDE_JVMCI
255 bool _using_dep_values;
256 GrowableArray<DepValue>* _dep_values[TYPE_LIMIT];
257 #endif
258
259 static const char* _dep_name[TYPE_LIMIT];
260 static int _dep_args[TYPE_LIMIT];
261
262 static bool dept_in_mask(DepType dept, int mask) {
263 return (int)dept >= 0 && dept < TYPE_LIMIT && ((1<<dept) & mask) != 0;
264 }
265
266 bool note_dep_seen(int dept, ciBaseObject* x) {
267 assert(dept < BitsPerInt, "oob");
268 int x_id = x->ident();
269 assert(_dep_seen != nullptr, "deps must be writable");
270 int seen = _dep_seen->at_grow(x_id, 0);
271 _dep_seen->at_put(x_id, seen | (1<<dept));
272 // return true if we've already seen dept/x
273 return (seen & (1<<dept)) != 0;
274 }
275
276 #if INCLUDE_JVMCI
277 bool note_dep_seen(int dept, DepValue x) {
278 assert(dept < BitsPerInt, "oops");
279 // place metadata deps at even indexes, object deps at odd indexes
280 int x_id = x.is_metadata() ? x.index() * 2 : (x.index() * 2) + 1;
281 assert(_dep_seen != nullptr, "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 #endif
288
289 bool maybe_merge_ctxk(GrowableArray<ciBaseObject*>* deps,
290 int ctxk_i, ciKlass* ctxk);
291 #if INCLUDE_JVMCI
292 bool maybe_merge_ctxk(GrowableArray<DepValue>* deps,
293 int ctxk_i, DepValue ctxk);
294 #endif
295
296 void sort_all_deps();
297 size_t estimate_size_in_bytes();
298
299 // Initialize _deps, etc.
300 void initialize(ciEnv* env);
301
302 // State for making a new set of dependencies:
303 OopRecorder* _oop_recorder;
304
305 // Logging support
306 CompileLog* _log;
307
308 address _content_bytes; // everything but the oop references, encoded
309 size_t _size_in_bytes;
310
311 public:
312 // Make a new empty dependencies set.
313 Dependencies(ciEnv* env) {
314 initialize(env);
315 }
316 #if INCLUDE_JVMCI
317 Dependencies(Arena* arena, OopRecorder* oop_recorder, CompileLog* log);
318 #endif
319
320 private:
321 // Check for a valid context type.
322 // Enforce the restriction against array types.
323 static void check_ctxk(ciKlass* ctxk) {
324 assert(ctxk->is_instance_klass(), "java types only");
325 }
326 static void check_ctxk_concrete(ciKlass* ctxk) {
327 assert(is_concrete_klass(ctxk->as_instance_klass()), "must be concrete");
328 }
329 static void check_ctxk_abstract(ciKlass* ctxk) {
330 check_ctxk(ctxk);
331 assert(!is_concrete_klass(ctxk->as_instance_klass()), "must be abstract");
332 }
333 static void check_unique_method(ciKlass* ctxk, ciMethod* m) {
334 assert(!m->can_be_statically_bound(ctxk->as_instance_klass()) || ctxk->is_interface(), "redundant");
335 }
336 static void check_unique_implementor(ciInstanceKlass* ctxk, ciInstanceKlass* uniqk) {
337 assert(ctxk->implementor() == uniqk, "not a unique implementor");
338 }
339
340 void assert_common_1(DepType dept, ciBaseObject* x);
341 void assert_common_2(DepType dept, ciBaseObject* x0, ciBaseObject* x1);
342 void assert_common_4(DepType dept, ciKlass* ctxk, ciBaseObject* x1, ciBaseObject* x2, ciBaseObject* x3);
343
344 public:
345 // Adding assertions to a new dependency set at compile time:
346 void assert_evol_method(ciMethod* m);
347 void assert_leaf_type(ciKlass* ctxk);
348 void assert_abstract_with_unique_concrete_subtype(ciKlass* ctxk, ciKlass* conck);
349 void assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm);
350 void assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm, ciKlass* resolved_klass, ciMethod* resolved_method);
351 void assert_unique_implementor(ciInstanceKlass* ctxk, ciInstanceKlass* uniqk);
352 void assert_has_no_finalizable_subclasses(ciKlass* ctxk);
353 void assert_call_site_target_value(ciCallSite* call_site, ciMethodHandle* method_handle);
354 #if INCLUDE_JVMCI
355 private:
356 static void check_ctxk(Klass* ctxk) {
357 assert(ctxk->is_instance_klass(), "java types only");
358 }
359 static void check_ctxk_abstract(Klass* ctxk) {
360 check_ctxk(ctxk);
361 assert(ctxk->is_abstract(), "must be abstract");
362 }
363 static void check_unique_method(Klass* ctxk, Method* m) {
364 assert(!m->can_be_statically_bound(InstanceKlass::cast(ctxk)), "redundant");
365 }
366
367 void assert_common_1(DepType dept, DepValue x);
368 void assert_common_2(DepType dept, DepValue x0, DepValue x1);
369
370 public:
371 void assert_evol_method(Method* m);
372 void assert_has_no_finalizable_subclasses(Klass* ctxk);
373 void assert_leaf_type(Klass* ctxk);
374 void assert_unique_implementor(InstanceKlass* ctxk, InstanceKlass* uniqk);
375 void assert_unique_concrete_method(Klass* ctxk, Method* uniqm);
376 void assert_abstract_with_unique_concrete_subtype(Klass* ctxk, Klass* conck);
377 void assert_call_site_target_value(oop callSite, oop methodHandle);
378 #endif // INCLUDE_JVMCI
379
380 // Define whether a given method or type is concrete.
381 // These methods define the term "concrete" as used in this module.
382 // For this module, an "abstract" class is one which is non-concrete.
383 //
384 // Future optimizations may allow some classes to remain
385 // non-concrete until their first instantiation, and allow some
386 // methods to remain non-concrete until their first invocation.
387 // In that case, there would be a middle ground between concrete
388 // and abstract (as defined by the Java language and VM).
389 static bool is_concrete_klass(Klass* k); // k is instantiable
390 static bool is_concrete_method(Method* m, Klass* k); // m is invocable
391 static Klass* find_finalizable_subclass(InstanceKlass* ik);
392
393 static bool is_concrete_root_method(Method* uniqm, InstanceKlass* ctxk);
394 static Klass* find_witness_AME(InstanceKlass* ctxk, Method* m, KlassDepChange* changes = nullptr);
395
396 // These versions of the concreteness queries work through the CI.
397 // The CI versions are allowed to skew sometimes from the VM
398 // (oop-based) versions. The cost of such a difference is a
399 // (safely) aborted compilation, or a deoptimization, or a missed
400 // optimization opportunity.
401 //
402 // In order to prevent spurious assertions, query results must
403 // remain stable within any single ciEnv instance. (I.e., they must
404 // not go back into the VM to get their value; they must cache the
405 // bit in the CI, either eagerly or lazily.)
406 static bool is_concrete_klass(ciInstanceKlass* k); // k appears instantiable
407 static bool has_finalizable_subclass(ciInstanceKlass* k);
408
409 // As a general rule, it is OK to compile under the assumption that
410 // a given type or method is concrete, even if it at some future
411 // point becomes abstract. So dependency checking is one-sided, in
412 // that it permits supposedly concrete classes or methods to turn up
413 // as really abstract. (This shouldn't happen, except during class
414 // evolution, but that's the logic of the checking.) However, if a
415 // supposedly abstract class or method suddenly becomes concrete, a
416 // dependency on it must fail.
417
418 // Checking old assertions at run-time (in the VM only):
419 static Klass* check_evol_method(Method* m);
420 static Klass* check_leaf_type(InstanceKlass* ctxk);
421 static Klass* check_abstract_with_unique_concrete_subtype(InstanceKlass* ctxk, Klass* conck, NewKlassDepChange* changes = nullptr);
422 static Klass* check_unique_implementor(InstanceKlass* ctxk, Klass* uniqk, NewKlassDepChange* changes = nullptr);
423 static Klass* check_unique_concrete_method(InstanceKlass* ctxk, Method* uniqm, NewKlassDepChange* changes = nullptr);
424 static Klass* check_unique_concrete_method(InstanceKlass* ctxk, Method* uniqm, Klass* resolved_klass, Method* resolved_method, KlassDepChange* changes = nullptr);
425 static Klass* check_has_no_finalizable_subclasses(InstanceKlass* ctxk, NewKlassDepChange* changes = nullptr);
426 static Klass* check_call_site_target_value(oop call_site, oop method_handle, CallSiteDepChange* changes = nullptr);
427 // A returned Klass* is nullptr if the dependency assertion is still
428 // valid. A non-nullptr Klass* is a 'witness' to the assertion
429 // failure, a point in the class hierarchy where the assertion has
430 // been proven false. For example, if check_leaf_type returns
431 // non-nullptr, the value is a subtype of the supposed leaf type. This
432 // witness value may be useful for logging the dependency failure.
433 // Note that, when a dependency fails, there may be several possible
434 // witnesses to the failure. The value returned from the check_foo
435 // method is chosen arbitrarily.
436
437 // The 'changes' value, if non-null, requests a limited spot-check
438 // near the indicated recent changes in the class hierarchy.
439 // It is used by DepStream::spot_check_dependency_at.
440
441 // Detecting possible new assertions:
442 static Klass* find_unique_concrete_subtype(InstanceKlass* ctxk);
443 static Method* find_unique_concrete_method(InstanceKlass* ctxk, Method* m,
444 Klass** participant = nullptr); // out parameter
445 static Method* find_unique_concrete_method(InstanceKlass* ctxk, Method* m, Klass* resolved_klass, Method* resolved_method);
446
447 #ifdef ASSERT
448 static bool verify_method_context(InstanceKlass* ctxk, Method* m);
449 #endif // ASSERT
450
451 // Create the encoding which will be stored in an nmethod.
452 void encode_content_bytes();
453
454 address content_bytes() {
455 assert(_content_bytes != nullptr, "encode it first");
456 return _content_bytes;
457 }
458 size_t size_in_bytes() {
459 assert(_content_bytes != nullptr, "encode it first");
460 return _size_in_bytes;
461 }
462
463 void set_content(address content_bytes, int size_in_bytes) {
464 assert(_content_bytes == nullptr, "not intialized expected");
465 _content_bytes = content_bytes;
466 _size_in_bytes = size_in_bytes;
467 }
468
469 OopRecorder* oop_recorder() { return _oop_recorder; }
470 CompileLog* log() { return _log; }
471
472 void copy_to(nmethod* nm);
473
474 static bool _verify_in_progress; // turn off logging dependencies
475
476 DepType validate_dependencies(CompileTask* task, char** failure_detail = nullptr);
477
478 void log_all_dependencies();
479
480 void log_dependency(DepType dept, GrowableArray<ciBaseObject*>* args) {
481 ResourceMark rm;
482 int argslen = args->length();
483 write_dependency_to(log(), dept, args);
484 guarantee(argslen == args->length(),
485 "args array cannot grow inside nested ResoureMark scope");
486 }
487
488 void log_dependency(DepType dept,
489 ciBaseObject* x0,
490 ciBaseObject* x1 = nullptr,
491 ciBaseObject* x2 = nullptr,
492 ciBaseObject* x3 = nullptr) {
493 if (log() == nullptr) {
494 return;
495 }
496 ResourceMark rm;
497 GrowableArray<ciBaseObject*>* ciargs =
498 new GrowableArray<ciBaseObject*>(dep_args(dept));
499 assert (x0 != nullptr, "no log x0");
500 ciargs->push(x0);
501
502 if (x1 != nullptr) {
503 ciargs->push(x1);
504 }
505 if (x2 != nullptr) {
506 ciargs->push(x2);
507 }
508 if (x3 != nullptr) {
509 ciargs->push(x3);
510 }
511 assert(ciargs->length() == dep_args(dept), "");
512 log_dependency(dept, ciargs);
513 }
514
515 class DepArgument : public ResourceObj {
516 private:
517 bool _is_oop;
518 bool _valid;
519 void* _value;
520 public:
521 DepArgument() : _is_oop(false), _valid(false), _value(nullptr) {}
522 DepArgument(oop v): _is_oop(true), _valid(true), _value(v) {}
523 DepArgument(Metadata* v): _is_oop(false), _valid(true), _value(v) {}
524
525 bool is_null() const { return _value == nullptr; }
526 bool is_oop() const { return _is_oop; }
527 bool is_metadata() const { return !_is_oop; }
528 bool is_klass() const { return is_metadata() && metadata_value()->is_klass(); }
529 bool is_method() const { return is_metadata() && metadata_value()->is_method(); }
530
531 oop oop_value() const { assert(_is_oop && _valid, "must be"); return cast_to_oop(_value); }
532 Metadata* metadata_value() const { assert(!_is_oop && _valid, "must be"); return (Metadata*) _value; }
533 };
534
535 static void print_dependency(DepType dept,
536 GrowableArray<DepArgument>* args,
537 Klass* witness = nullptr, outputStream* st = tty);
538
539 private:
540 // helper for encoding common context types as zero:
541 static ciKlass* ctxk_encoded_as_null(DepType dept, ciBaseObject* x);
542
543 static Klass* ctxk_encoded_as_null(DepType dept, Metadata* x);
544
545 static void write_dependency_to(CompileLog* log,
546 DepType dept,
547 GrowableArray<ciBaseObject*>* args,
548 Klass* witness = nullptr);
549 static void write_dependency_to(CompileLog* log,
550 DepType dept,
551 GrowableArray<DepArgument>* args,
552 Klass* witness = nullptr);
553 static void write_dependency_to(xmlStream* xtty,
554 DepType dept,
555 GrowableArray<DepArgument>* args,
556 Klass* witness = nullptr);
557 public:
558 // Use this to iterate over an nmethod's dependency set.
559 // Works on new and old dependency sets.
560 // Usage:
561 //
562 // ;
563 // Dependencies::DepType dept;
564 // for (Dependencies::DepStream deps(nm); deps.next(); ) {
565 // ...
566 // }
567 //
568 // The caller must be in the VM, since oops are not wrapped in handles.
569 class DepStream {
570 private:
571 nmethod* _code; // null if in a compiler thread
572 Dependencies* _deps; // null if not in a compiler thread
573 CompressedReadStream _bytes;
574 #ifdef ASSERT
575 size_t _byte_limit;
576 #endif
577
578 // iteration variables:
579 DepType _type;
580 int _xi[max_arg_count+1];
581
582 void initial_asserts(size_t byte_limit) NOT_DEBUG({});
583
584 inline Metadata* recorded_metadata_at(int i);
585 inline oop recorded_oop_at(int i);
586
587 Klass* check_klass_dependency(KlassDepChange* changes);
588 Klass* check_new_klass_dependency(NewKlassDepChange* changes);
589 Klass* check_klass_init_dependency(KlassInitDepChange* changes);
590 Klass* check_call_site_dependency(CallSiteDepChange* changes);
591
592 void trace_and_log_witness(Klass* witness);
593
594 public:
595 DepStream(Dependencies* deps)
596 : _code(nullptr),
597 _deps(deps),
598 _bytes(deps->content_bytes())
599 {
600 initial_asserts(deps->size_in_bytes());
601 }
602 DepStream(nmethod* code)
603 : _code(code),
604 _deps(nullptr),
605 _bytes(code->dependencies_begin())
606 {
607 initial_asserts(code->dependencies_size());
608 }
609
610 bool next();
611
612 DepType type() { return _type; }
613 bool is_oop_argument(int i) { return type() == call_site_target_value; }
614 uintptr_t get_identifier(int i);
615
616 int argument_count() { return dep_args(type()); }
617 int argument_index(int i) { assert(0 <= i && i < argument_count(), "oob");
618 return _xi[i]; }
619 Metadata* argument(int i); // => recorded_oop_at(argument_index(i))
620 oop argument_oop(int i); // => recorded_oop_at(argument_index(i))
621 InstanceKlass* context_type();
622
623 bool is_klass_type() { return Dependencies::is_klass_type(type()); }
624
625 Method* method_argument(int i) {
626 Metadata* x = argument(i);
627 assert(x->is_method(), "type");
628 return (Method*) x;
629 }
630 Klass* type_argument(int i) {
631 Metadata* x = argument(i);
632 assert(x->is_klass(), "type");
633 return (Klass*) x;
634 }
635
636 // The point of the whole exercise: Is this dep still OK?
637 Klass* check_dependency() {
638 Klass* result = check_klass_dependency(nullptr);
639 if (result != nullptr) return result;
640 return check_call_site_dependency(nullptr);
641 }
642
643 // A lighter version: Checks only around recent changes in a class
644 // hierarchy. (See Universe::flush_dependents_on.)
645 Klass* spot_check_dependency_at(DepChange& changes);
646
647 // Log the current dependency to xtty or compilation log.
648 void log_dependency(Klass* witness = nullptr);
649
650 // Print the current dependency to tty.
651 void print_dependency(outputStream* st, Klass* witness = nullptr, bool verbose = false);
652 };
653 friend class Dependencies::DepStream;
654
655 static void print_statistics();
656 };
657
658
659 class DependencySignature : public ResourceObj {
660 private:
661 int _args_count;
662 uintptr_t _argument_hash[Dependencies::max_arg_count];
663 Dependencies::DepType _type;
664
665 public:
666 DependencySignature(Dependencies::DepStream& dep) {
667 _args_count = dep.argument_count();
668 _type = dep.type();
669 for (int i = 0; i < _args_count; i++) {
670 _argument_hash[i] = dep.get_identifier(i);
671 }
672 }
673
674 static bool equals(DependencySignature const& s1, DependencySignature const& s2);
675 static unsigned hash (DependencySignature const& s1) { return (unsigned)(s1.arg(0) >> 2); }
676
677 int args_count() const { return _args_count; }
678 uintptr_t arg(int idx) const { return _argument_hash[idx]; }
679 Dependencies::DepType type() const { return _type; }
680
681 };
682
683
684 // Every particular DepChange is a sub-class of this class.
685 class DepChange : public StackObj {
686 public:
687 // What kind of DepChange is this?
688 virtual bool is_klass_change() const { return false; }
689 virtual bool is_new_klass_change() const { return false; }
690 virtual bool is_klass_init_change() const { return false; }
691 virtual bool is_call_site_change() const { return false; }
692
693 // Subclass casting with assertions.
694 KlassDepChange* as_klass_change() {
695 assert(is_klass_change(), "bad cast");
696 return (KlassDepChange*) this;
697 }
698 NewKlassDepChange* as_new_klass_change() {
699 assert(is_new_klass_change(), "bad cast");
700 return (NewKlassDepChange*) this;
701 }
702 KlassInitDepChange* as_klass_init_change() {
703 assert(is_klass_init_change(), "bad cast");
704 return (KlassInitDepChange*) this;
705 }
706 CallSiteDepChange* as_call_site_change() {
707 assert(is_call_site_change(), "bad cast");
708 return (CallSiteDepChange*) this;
709 }
710
711 void print();
712 void print_on(outputStream* st);
713
714 public:
715 enum ChangeType {
716 NO_CHANGE = 0, // an uninvolved klass
717 Change_new_type, // a newly loaded type
718 Change_new_sub, // a super with a new subtype
719 Change_new_impl, // an interface with a new implementation
720 CHANGE_LIMIT,
721 Start_Klass = CHANGE_LIMIT // internal indicator for ContextStream
722 };
723
724 // Usage:
725 // for (DepChange::ContextStream str(changes); str.next(); ) {
726 // InstanceKlass* k = str.klass();
727 // switch (str.change_type()) {
728 // ...
729 // }
730 // }
731 class ContextStream : public StackObj {
732 private:
733 DepChange& _changes;
734 friend class DepChange;
735
736 // iteration variables:
737 ChangeType _change_type;
738 InstanceKlass* _klass;
739 Array<InstanceKlass*>* _ti_base; // i.e., transitive_interfaces
740 int _ti_index;
741 int _ti_limit;
742
743 // start at the beginning:
744 void start();
745
746 public:
747 ContextStream(DepChange& changes)
748 : _changes(changes)
749 { start(); }
750
751 ContextStream(DepChange& changes, NoSafepointVerifier& nsv)
752 : _changes(changes)
753 // the nsv argument makes it safe to hold oops like _klass
754 { start(); }
755
756 bool next();
757
758 ChangeType change_type() { return _change_type; }
759 InstanceKlass* klass() { return _klass; }
760 };
761 friend class DepChange::ContextStream;
762 };
763
764
765 // A class hierarchy change coming through the VM (under the Compile_lock).
766 // The change is structured as a single type with any number of supers
767 // and implemented interface types. Other than the type, any of the
768 // super types can be context types for a relevant dependency, which the
769 // type could invalidate.
770 class KlassDepChange : public DepChange {
771 private:
772 // each change set is rooted in exactly one type (at present):
773 InstanceKlass* _type;
774
775 void initialize();
776
777 protected:
778 // notes the type, marks it and all its super-types
779 KlassDepChange(InstanceKlass* type) : _type(type) {
780 initialize();
781 }
782
783 // cleans up the marks
784 ~KlassDepChange();
785
786 public:
787 // What kind of DepChange is this?
788 virtual bool is_klass_change() const { return true; }
789
790 InstanceKlass* type() { return _type; }
791
792 // involves_context(k) is true if k == _type or any of its super types
793 bool involves_context(Klass* k);
794 };
795
796 // A class hierarchy change: new type is loaded.
797 class NewKlassDepChange : public KlassDepChange {
798 public:
799 NewKlassDepChange(InstanceKlass* new_type) : KlassDepChange(new_type) {}
800
801 // What kind of DepChange is this?
802 virtual bool is_new_klass_change() const { return true; }
803
804 InstanceKlass* new_type() { return type(); }
805 };
806
807 // Change in initialization state of a loaded class.
808 class KlassInitDepChange : public KlassDepChange {
809 public:
810 KlassInitDepChange(InstanceKlass* type) : KlassDepChange(type) {}
811
812 // What kind of DepChange is this?
813 virtual bool is_klass_init_change() const { return true; }
814 };
815
816 // A CallSite has changed its target.
817 class CallSiteDepChange : public DepChange {
818 private:
819 Handle _call_site;
820 Handle _method_handle;
821
822 public:
823 CallSiteDepChange(Handle call_site, Handle method_handle);
824
825 // What kind of DepChange is this?
826 virtual bool is_call_site_change() const { return true; }
827
828 oop call_site() const { return _call_site(); }
829 oop method_handle() const { return _method_handle(); }
830 };
831
832 #endif // SHARE_CODE_DEPENDENCIES_HPP