1 /*
2 * Copyright (c) 2005, 2024, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
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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 // _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) 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) is just {M1}, or
137 // perhaps a set of two {M1,M2}, and issue dependencies on this.
138
139 // The set MM(CX, M1) 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 method M1 and the
144 // context class CX. M1 must be either inherited in CX or defined
145 // in a subtype* of CX. It asserts that MM(CX, M1) is no greater
146 // than {M1}.
147 unique_concrete_method_2, // one unique concrete method under CX
148
149 // In addition to the method M1 and the context class CX, the parameters
150 // to this dependency are the resolved class RC1 and the
151 // resolved method RM1. It asserts that MM(CX, M1, RC1, RM1)
152 // is no greater than {M1}. RC1 and RM1 are used to improve the precision
153 // of the analysis.
154 unique_concrete_method_4, // one unique concrete method under CX
155
156 // This dependency asserts that interface CX has a unique implementor class.
157 unique_implementor, // one unique implementor under CX
158
159 // This dependency asserts that no instances of class or it's
160 // subclasses require finalization registration.
161 no_finalizable_subclasses,
162
163 // This dependency asserts when the CallSite.target value changed.
164 call_site_target_value,
165
166 TYPE_LIMIT
167 };
168 enum {
169 LG2_TYPE_LIMIT = 4, // assert(TYPE_LIMIT <= (1<<LG2_TYPE_LIMIT))
170
171 // handy categorizations of dependency types:
172 all_types = ((1 << TYPE_LIMIT) - 1) & ((~0u) << FIRST_TYPE),
173
174 non_klass_types = (1 << call_site_target_value),
175 klass_types = all_types & ~non_klass_types,
176
177 non_ctxk_types = (1 << evol_method) | (1 << mismatch_calling_convention) | (1 << call_site_target_value),
178 implicit_ctxk_types = 0,
179 explicit_ctxk_types = all_types & ~(non_ctxk_types | implicit_ctxk_types),
180
181 max_arg_count = 4, // current maximum number of arguments (incl. ctxk)
182
183 // A "context type" is a class or interface that
184 // provides context for evaluating a dependency.
185 // When present, it is one of the arguments (dep_context_arg).
186 //
187 // If a dependency does not have a context type, there is a
188 // default context, depending on the type of the dependency.
189 // This bit signals that a default context has been compressed away.
190 default_context_type_bit = (1<<LG2_TYPE_LIMIT),
191
192 method_types = (1 << evol_method) | (1 << mismatch_calling_convention),
193 };
194
195 static const char* dep_name(DepType dept);
196 static int dep_args(DepType dept);
197
198 static bool is_klass_type( DepType dept) { return dept_in_mask(dept, klass_types ); }
199
200 static bool has_explicit_context_arg(DepType dept) { return dept_in_mask(dept, explicit_ctxk_types); }
201 static bool has_implicit_context_arg(DepType dept) { return dept_in_mask(dept, implicit_ctxk_types); }
202
203 static bool has_method_dep(DepType dept) { return dept_in_mask(dept, method_types); }
204
205 static int dep_context_arg(DepType dept) { return has_explicit_context_arg(dept) ? 0 : -1; }
206 static int dep_implicit_context_arg(DepType dept) { return has_implicit_context_arg(dept) ? 0 : -1; }
207
208 static void check_valid_dependency_type(DepType dept);
209
210 #if INCLUDE_JVMCI
211 // A Metadata* or object value recorded in an OopRecorder
212 class DepValue {
213 private:
214 // Unique identifier of the value within the associated OopRecorder that
215 // encodes both the category of the value (0: invalid, positive: metadata, negative: object)
216 // and the index within a category specific array (metadata: index + 1, object: -(index + 1))
217 int _id;
218
219 public:
220 DepValue() : _id(0) {}
221 DepValue(OopRecorder* rec, Metadata* metadata, DepValue* candidate = nullptr) {
222 assert(candidate == nullptr || candidate->is_metadata(), "oops");
223 if (candidate != nullptr && candidate->as_metadata(rec) == metadata) {
224 _id = candidate->_id;
225 } else {
226 _id = rec->find_index(metadata) + 1;
227 }
228 }
229 DepValue(OopRecorder* rec, jobject obj, DepValue* candidate = nullptr) {
230 assert(candidate == nullptr || candidate->is_object(), "oops");
231 if (candidate != nullptr && candidate->as_object(rec) == obj) {
232 _id = candidate->_id;
233 } else {
234 _id = -(rec->find_index(obj) + 1);
235 }
236 }
237
238 // Used to sort values in ascending order of index() with metadata values preceding object values
239 int sort_key() const { return -_id; }
240
241 bool operator == (const DepValue& other) const { return other._id == _id; }
242
243 bool is_valid() const { return _id != 0; }
244 int index() const { assert(is_valid(), "oops"); return _id < 0 ? -(_id + 1) : _id - 1; }
245 bool is_metadata() const { assert(is_valid(), "oops"); return _id > 0; }
246 bool is_object() const { assert(is_valid(), "oops"); return _id < 0; }
247
248 Metadata* as_metadata(OopRecorder* rec) const { assert(is_metadata(), "oops"); return rec->metadata_at(index()); }
249 Klass* as_klass(OopRecorder* rec) const {
250 Metadata* m = as_metadata(rec);
251 assert(m != nullptr, "as_metadata returned nullptr");
252 assert(m->is_klass(), "oops");
253 return (Klass*) m;
254 }
255 Method* as_method(OopRecorder* rec) const {
256 Metadata* m = as_metadata(rec);
257 assert(m != nullptr, "as_metadata returned nullptr");
258 assert(m->is_method(), "oops");
259 return (Method*) m;
260 }
261 jobject as_object(OopRecorder* rec) const { assert(is_object(), "oops"); return rec->oop_at(index()); }
262 };
263 #endif // INCLUDE_JVMCI
264
265 private:
266 // State for writing a new set of dependencies:
267 GrowableArray<int>* _dep_seen; // (seen[h->ident] & (1<<dept))
268 GrowableArray<ciBaseObject*>* _deps[TYPE_LIMIT];
269 #if INCLUDE_JVMCI
270 bool _using_dep_values;
271 GrowableArray<DepValue>* _dep_values[TYPE_LIMIT];
272 #endif
273
274 static const char* _dep_name[TYPE_LIMIT];
275 static int _dep_args[TYPE_LIMIT];
276
277 static bool dept_in_mask(DepType dept, int mask) {
278 return (int)dept >= 0 && dept < TYPE_LIMIT && ((1<<dept) & mask) != 0;
279 }
280
281 bool note_dep_seen(int dept, ciBaseObject* x) {
282 assert(dept < BitsPerInt, "oob");
283 int x_id = x->ident();
284 assert(_dep_seen != nullptr, "deps must be writable");
285 int seen = _dep_seen->at_grow(x_id, 0);
286 _dep_seen->at_put(x_id, seen | (1<<dept));
287 // return true if we've already seen dept/x
288 return (seen & (1<<dept)) != 0;
289 }
290
291 #if INCLUDE_JVMCI
292 bool note_dep_seen(int dept, DepValue x) {
293 assert(dept < BitsPerInt, "oops");
294 // place metadata deps at even indexes, object deps at odd indexes
295 int x_id = x.is_metadata() ? x.index() * 2 : (x.index() * 2) + 1;
296 assert(_dep_seen != nullptr, "deps must be writable");
297 int seen = _dep_seen->at_grow(x_id, 0);
298 _dep_seen->at_put(x_id, seen | (1<<dept));
299 // return true if we've already seen dept/x
300 return (seen & (1<<dept)) != 0;
301 }
302 #endif
303
304 bool maybe_merge_ctxk(GrowableArray<ciBaseObject*>* deps,
305 int ctxk_i, ciKlass* ctxk);
306 #if INCLUDE_JVMCI
307 bool maybe_merge_ctxk(GrowableArray<DepValue>* deps,
308 int ctxk_i, DepValue ctxk);
309 #endif
310
311 void sort_all_deps();
312 size_t estimate_size_in_bytes();
313
314 // Initialize _deps, etc.
315 void initialize(ciEnv* env);
316
317 // State for making a new set of dependencies:
318 OopRecorder* _oop_recorder;
319
320 // Logging support
321 CompileLog* _log;
322
323 address _content_bytes; // everything but the oop references, encoded
324 size_t _size_in_bytes;
325
326 public:
327 // Make a new empty dependencies set.
328 Dependencies(ciEnv* env) {
329 initialize(env);
330 }
331 #if INCLUDE_JVMCI
332 Dependencies(Arena* arena, OopRecorder* oop_recorder, CompileLog* log);
333 #endif
334
335 private:
336 // Check for a valid context type.
337 // Enforce the restriction against array types.
338 static void check_ctxk(ciKlass* ctxk) {
339 assert(ctxk->is_instance_klass(), "java types only");
340 }
341 static void check_ctxk_concrete(ciKlass* ctxk) {
342 assert(is_concrete_klass(ctxk->as_instance_klass()), "must be concrete");
343 }
344 static void check_ctxk_abstract(ciKlass* ctxk) {
345 check_ctxk(ctxk);
346 assert(!is_concrete_klass(ctxk->as_instance_klass()), "must be abstract");
347 }
348 static void check_unique_method(ciKlass* ctxk, ciMethod* m) {
349 assert(!m->can_be_statically_bound(ctxk->as_instance_klass()) || ctxk->is_interface(), "redundant");
350 }
351 static void check_unique_implementor(ciInstanceKlass* ctxk, ciInstanceKlass* uniqk) {
352 assert(ctxk->implementor() == uniqk, "not a unique implementor");
353 }
354
355 void assert_common_1(DepType dept, ciBaseObject* x);
356 void assert_common_2(DepType dept, ciBaseObject* x0, ciBaseObject* x1);
357 void assert_common_4(DepType dept, ciKlass* ctxk, ciBaseObject* x1, ciBaseObject* x2, ciBaseObject* x3);
358
359 public:
360 // Adding assertions to a new dependency set at compile time:
361 void assert_evol_method(ciMethod* m);
362 void assert_mismatch_calling_convention(ciMethod* m);
363 void assert_leaf_type(ciKlass* ctxk);
364 void assert_abstract_with_unique_concrete_subtype(ciKlass* ctxk, ciKlass* conck);
365 void assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm);
366 void assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm, ciKlass* resolved_klass, ciMethod* resolved_method);
367 void assert_unique_implementor(ciInstanceKlass* ctxk, ciInstanceKlass* uniqk);
368 void assert_has_no_finalizable_subclasses(ciKlass* ctxk);
369 void assert_call_site_target_value(ciCallSite* call_site, ciMethodHandle* method_handle);
370 #if INCLUDE_JVMCI
371 private:
372 static void check_ctxk(Klass* ctxk) {
373 assert(ctxk->is_instance_klass(), "java types only");
374 }
375 static void check_ctxk_abstract(Klass* ctxk) {
376 check_ctxk(ctxk);
377 assert(ctxk->is_abstract(), "must be abstract");
378 }
379 static void check_unique_method(Klass* ctxk, Method* m) {
380 assert(!m->can_be_statically_bound(InstanceKlass::cast(ctxk)), "redundant");
381 }
382
383 void assert_common_1(DepType dept, DepValue x);
384 void assert_common_2(DepType dept, DepValue x0, DepValue x1);
385
386 public:
387 void assert_evol_method(Method* m);
388 void assert_has_no_finalizable_subclasses(Klass* ctxk);
389 void assert_leaf_type(Klass* ctxk);
390 void assert_unique_implementor(InstanceKlass* ctxk, InstanceKlass* uniqk);
391 void assert_unique_concrete_method(Klass* ctxk, Method* uniqm);
392 void assert_abstract_with_unique_concrete_subtype(Klass* ctxk, Klass* conck);
393 void assert_call_site_target_value(oop callSite, oop methodHandle);
394 #endif // INCLUDE_JVMCI
395
396 // Define whether a given method or type is concrete.
397 // These methods define the term "concrete" as used in this module.
398 // For this module, an "abstract" class is one which is non-concrete.
399 //
400 // Future optimizations may allow some classes to remain
401 // non-concrete until their first instantiation, and allow some
402 // methods to remain non-concrete until their first invocation.
403 // In that case, there would be a middle ground between concrete
404 // and abstract (as defined by the Java language and VM).
405 static bool is_concrete_klass(Klass* k); // k is instantiable
406 static bool is_concrete_method(Method* m, Klass* k); // m is invocable
407 static Klass* find_finalizable_subclass(InstanceKlass* ik);
408
409 static bool is_concrete_root_method(Method* uniqm, InstanceKlass* ctxk);
410 static Klass* find_witness_AME(InstanceKlass* ctxk, Method* m, KlassDepChange* changes = nullptr);
411
412 // These versions of the concreteness queries work through the CI.
413 // The CI versions are allowed to skew sometimes from the VM
414 // (oop-based) versions. The cost of such a difference is a
415 // (safely) aborted compilation, or a deoptimization, or a missed
416 // optimization opportunity.
417 //
418 // In order to prevent spurious assertions, query results must
419 // remain stable within any single ciEnv instance. (I.e., they must
420 // not go back into the VM to get their value; they must cache the
421 // bit in the CI, either eagerly or lazily.)
422 static bool is_concrete_klass(ciInstanceKlass* k); // k appears instantiable
423 static bool has_finalizable_subclass(ciInstanceKlass* k);
424
425 // As a general rule, it is OK to compile under the assumption that
426 // a given type or method is concrete, even if it at some future
427 // point becomes abstract. So dependency checking is one-sided, in
428 // that it permits supposedly concrete classes or methods to turn up
429 // as really abstract. (This shouldn't happen, except during class
430 // evolution, but that's the logic of the checking.) However, if a
431 // supposedly abstract class or method suddenly becomes concrete, a
432 // dependency on it must fail.
433
434 // Checking old assertions at run-time (in the VM only):
435 static Klass* check_evol_method(Method* m);
436 static Klass* check_mismatch_calling_convention(Method* m);
437 static Klass* check_leaf_type(InstanceKlass* ctxk);
438 static Klass* check_abstract_with_unique_concrete_subtype(InstanceKlass* ctxk, Klass* conck, NewKlassDepChange* changes = nullptr);
439 static Klass* check_unique_implementor(InstanceKlass* ctxk, Klass* uniqk, NewKlassDepChange* changes = nullptr);
440 static Klass* check_unique_concrete_method(InstanceKlass* ctxk, Method* uniqm, NewKlassDepChange* changes = nullptr);
441 static Klass* check_unique_concrete_method(InstanceKlass* ctxk, Method* uniqm, Klass* resolved_klass, Method* resolved_method, KlassDepChange* changes = nullptr);
442 static Klass* check_has_no_finalizable_subclasses(InstanceKlass* ctxk, NewKlassDepChange* changes = nullptr);
443 static Klass* check_call_site_target_value(oop call_site, oop method_handle, CallSiteDepChange* changes = nullptr);
444 // A returned Klass* is nullptr if the dependency assertion is still
445 // valid. A non-nullptr Klass* is a 'witness' to the assertion
446 // failure, a point in the class hierarchy where the assertion has
447 // been proven false. For example, if check_leaf_type returns
448 // non-nullptr, the value is a subtype of the supposed leaf type. This
449 // witness value may be useful for logging the dependency failure.
450 // Note that, when a dependency fails, there may be several possible
451 // witnesses to the failure. The value returned from the check_foo
452 // method is chosen arbitrarily.
453
454 // The 'changes' value, if non-null, requests a limited spot-check
455 // near the indicated recent changes in the class hierarchy.
456 // It is used by DepStream::spot_check_dependency_at.
457
458 // Detecting possible new assertions:
459 static Klass* find_unique_concrete_subtype(InstanceKlass* ctxk);
460 static Method* find_unique_concrete_method(InstanceKlass* ctxk, Method* m,
461 Klass** participant = nullptr); // out parameter
462 static Method* find_unique_concrete_method(InstanceKlass* ctxk, Method* m, Klass* resolved_klass, Method* resolved_method);
463
464 #ifdef ASSERT
465 static bool verify_method_context(InstanceKlass* ctxk, Method* m);
466 #endif // ASSERT
467
468 // Create the encoding which will be stored in an nmethod.
469 void encode_content_bytes();
470
471 address content_bytes() {
472 assert(_content_bytes != nullptr, "encode it first");
473 return _content_bytes;
474 }
475 size_t size_in_bytes() {
476 assert(_content_bytes != nullptr, "encode it first");
477 return _size_in_bytes;
478 }
479
480 OopRecorder* oop_recorder() { return _oop_recorder; }
481 CompileLog* log() { return _log; }
482
483 void copy_to(nmethod* nm);
484
485 static bool _verify_in_progress; // turn off logging dependencies
486
487 DepType validate_dependencies(CompileTask* task, char** failure_detail = nullptr);
488
489 void log_all_dependencies();
490
491 void log_dependency(DepType dept, GrowableArray<ciBaseObject*>* args) {
492 ResourceMark rm;
493 int argslen = args->length();
494 write_dependency_to(log(), dept, args);
495 guarantee(argslen == args->length(),
496 "args array cannot grow inside nested ResoureMark scope");
497 }
498
499 void log_dependency(DepType dept,
500 ciBaseObject* x0,
501 ciBaseObject* x1 = nullptr,
502 ciBaseObject* x2 = nullptr,
503 ciBaseObject* x3 = nullptr) {
504 if (log() == nullptr) {
505 return;
506 }
507 ResourceMark rm;
508 GrowableArray<ciBaseObject*>* ciargs =
509 new GrowableArray<ciBaseObject*>(dep_args(dept));
510 assert (x0 != nullptr, "no log x0");
511 ciargs->push(x0);
512
513 if (x1 != nullptr) {
514 ciargs->push(x1);
515 }
516 if (x2 != nullptr) {
517 ciargs->push(x2);
518 }
519 if (x3 != nullptr) {
520 ciargs->push(x3);
521 }
522 assert(ciargs->length() == dep_args(dept), "");
523 log_dependency(dept, ciargs);
524 }
525
526 class DepArgument : public ResourceObj {
527 private:
528 bool _is_oop;
529 bool _valid;
530 void* _value;
531 public:
532 DepArgument() : _is_oop(false), _valid(false), _value(nullptr) {}
533 DepArgument(oop v): _is_oop(true), _valid(true), _value(v) {}
534 DepArgument(Metadata* v): _is_oop(false), _valid(true), _value(v) {}
535
536 bool is_null() const { return _value == nullptr; }
537 bool is_oop() const { return _is_oop; }
538 bool is_metadata() const { return !_is_oop; }
539 bool is_klass() const { return is_metadata() && metadata_value()->is_klass(); }
540 bool is_method() const { return is_metadata() && metadata_value()->is_method(); }
541
542 oop oop_value() const { assert(_is_oop && _valid, "must be"); return cast_to_oop(_value); }
543 Metadata* metadata_value() const { assert(!_is_oop && _valid, "must be"); return (Metadata*) _value; }
544 };
545
546 static void print_dependency(DepType dept,
547 GrowableArray<DepArgument>* args,
548 Klass* witness = nullptr, outputStream* st = tty);
549
550 private:
551 // helper for encoding common context types as zero:
552 static ciKlass* ctxk_encoded_as_null(DepType dept, ciBaseObject* x);
553
554 static Klass* ctxk_encoded_as_null(DepType dept, Metadata* x);
555
556 static void write_dependency_to(CompileLog* log,
557 DepType dept,
558 GrowableArray<ciBaseObject*>* args,
559 Klass* witness = nullptr);
560 static void write_dependency_to(CompileLog* log,
561 DepType dept,
562 GrowableArray<DepArgument>* args,
563 Klass* witness = nullptr);
564 static void write_dependency_to(xmlStream* xtty,
565 DepType dept,
566 GrowableArray<DepArgument>* args,
567 Klass* witness = nullptr);
568 public:
569 // Use this to iterate over an nmethod's dependency set.
570 // Works on new and old dependency sets.
571 // Usage:
572 //
573 // ;
574 // Dependencies::DepType dept;
575 // for (Dependencies::DepStream deps(nm); deps.next(); ) {
576 // ...
577 // }
578 //
579 // The caller must be in the VM, since oops are not wrapped in handles.
580 class DepStream {
581 private:
582 nmethod* _code; // null if in a compiler thread
583 Dependencies* _deps; // null if not in a compiler thread
584 CompressedReadStream _bytes;
585 #ifdef ASSERT
586 size_t _byte_limit;
587 #endif
588
589 // iteration variables:
590 DepType _type;
591 int _xi[max_arg_count+1];
592
593 void initial_asserts(size_t byte_limit) NOT_DEBUG({});
594
595 inline Metadata* recorded_metadata_at(int i);
596 inline oop recorded_oop_at(int i);
597
598 Klass* check_klass_dependency(KlassDepChange* changes);
599 Klass* check_new_klass_dependency(NewKlassDepChange* changes);
600 Klass* check_klass_init_dependency(KlassInitDepChange* changes);
601 Klass* check_call_site_dependency(CallSiteDepChange* changes);
602
603 void trace_and_log_witness(Klass* witness);
604
605 public:
606 DepStream(Dependencies* deps)
607 : _code(nullptr),
608 _deps(deps),
609 _bytes(deps->content_bytes())
610 {
611 initial_asserts(deps->size_in_bytes());
612 }
613 DepStream(nmethod* code)
614 : _code(code),
615 _deps(nullptr),
616 _bytes(code->dependencies_begin())
617 {
618 initial_asserts(code->dependencies_size());
619 }
620
621 bool next();
622
623 DepType type() { return _type; }
624 bool is_oop_argument(int i) { return type() == call_site_target_value; }
625 uintptr_t get_identifier(int i);
626
627 int argument_count() { return dep_args(type()); }
628 int argument_index(int i) { assert(0 <= i && i < argument_count(), "oob");
629 return _xi[i]; }
630 Metadata* argument(int i); // => recorded_oop_at(argument_index(i))
631 oop argument_oop(int i); // => recorded_oop_at(argument_index(i))
632 InstanceKlass* context_type();
633
634 bool is_klass_type() { return Dependencies::is_klass_type(type()); }
635
636 Method* method_argument(int i) {
637 Metadata* x = argument(i);
638 assert(x->is_method(), "type");
639 return (Method*) x;
640 }
641 Klass* type_argument(int i) {
642 Metadata* x = argument(i);
643 assert(x->is_klass(), "type");
644 return (Klass*) x;
645 }
646
647 // The point of the whole exercise: Is this dep still OK?
648 Klass* check_dependency() {
649 Klass* result = check_klass_dependency(nullptr);
650 if (result != nullptr) return result;
651 return check_call_site_dependency(nullptr);
652 }
653
654 // A lighter version: Checks only around recent changes in a class
655 // hierarchy. (See Universe::flush_dependents_on.)
656 Klass* spot_check_dependency_at(DepChange& changes);
657
658 // Log the current dependency to xtty or compilation log.
659 void log_dependency(Klass* witness = nullptr);
660
661 // Print the current dependency to tty.
662 void print_dependency(outputStream* st, Klass* witness = nullptr, bool verbose = false);
663 };
664 friend class Dependencies::DepStream;
665
666 static void print_statistics();
667 };
668
669
670 class DependencySignature : public ResourceObj {
671 private:
672 int _args_count;
673 uintptr_t _argument_hash[Dependencies::max_arg_count];
674 Dependencies::DepType _type;
675
676 public:
677 DependencySignature(Dependencies::DepStream& dep) {
678 _args_count = dep.argument_count();
679 _type = dep.type();
680 for (int i = 0; i < _args_count; i++) {
681 _argument_hash[i] = dep.get_identifier(i);
682 }
683 }
684
685 static bool equals(DependencySignature const& s1, DependencySignature const& s2);
686 static unsigned hash (DependencySignature const& s1) { return (unsigned)(s1.arg(0) >> 2); }
687
688 int args_count() const { return _args_count; }
689 uintptr_t arg(int idx) const { return _argument_hash[idx]; }
690 Dependencies::DepType type() const { return _type; }
691
692 };
693
694
695 // Every particular DepChange is a sub-class of this class.
696 class DepChange : public StackObj {
697 public:
698 // What kind of DepChange is this?
699 virtual bool is_klass_change() const { return false; }
700 virtual bool is_new_klass_change() const { return false; }
701 virtual bool is_klass_init_change() const { return false; }
702 virtual bool is_call_site_change() const { return false; }
703
704 // Subclass casting with assertions.
705 KlassDepChange* as_klass_change() {
706 assert(is_klass_change(), "bad cast");
707 return (KlassDepChange*) this;
708 }
709 NewKlassDepChange* as_new_klass_change() {
710 assert(is_new_klass_change(), "bad cast");
711 return (NewKlassDepChange*) this;
712 }
713 KlassInitDepChange* as_klass_init_change() {
714 assert(is_klass_init_change(), "bad cast");
715 return (KlassInitDepChange*) this;
716 }
717 CallSiteDepChange* as_call_site_change() {
718 assert(is_call_site_change(), "bad cast");
719 return (CallSiteDepChange*) this;
720 }
721
722 void print();
723 void print_on(outputStream* st);
724
725 public:
726 enum ChangeType {
727 NO_CHANGE = 0, // an uninvolved klass
728 Change_new_type, // a newly loaded type
729 Change_new_sub, // a super with a new subtype
730 Change_new_impl, // an interface with a new implementation
731 CHANGE_LIMIT,
732 Start_Klass = CHANGE_LIMIT // internal indicator for ContextStream
733 };
734
735 // Usage:
736 // for (DepChange::ContextStream str(changes); str.next(); ) {
737 // InstanceKlass* k = str.klass();
738 // switch (str.change_type()) {
739 // ...
740 // }
741 // }
742 class ContextStream : public StackObj {
743 private:
744 DepChange& _changes;
745 friend class DepChange;
746
747 // iteration variables:
748 ChangeType _change_type;
749 InstanceKlass* _klass;
750 Array<InstanceKlass*>* _ti_base; // i.e., transitive_interfaces
751 int _ti_index;
752 int _ti_limit;
753
754 // start at the beginning:
755 void start();
756
757 public:
758 ContextStream(DepChange& changes)
759 : _changes(changes)
760 { start(); }
761
762 ContextStream(DepChange& changes, NoSafepointVerifier& nsv)
763 : _changes(changes)
764 // the nsv argument makes it safe to hold oops like _klass
765 { start(); }
766
767 bool next();
768
769 ChangeType change_type() { return _change_type; }
770 InstanceKlass* klass() { return _klass; }
771 };
772 friend class DepChange::ContextStream;
773 };
774
775
776 // A class hierarchy change coming through the VM (under the Compile_lock).
777 // The change is structured as a single type with any number of supers
778 // and implemented interface types. Other than the type, any of the
779 // super types can be context types for a relevant dependency, which the
780 // type could invalidate.
781 class KlassDepChange : public DepChange {
782 private:
783 // each change set is rooted in exactly one type (at present):
784 InstanceKlass* _type;
785
786 void initialize();
787
788 protected:
789 // notes the type, marks it and all its super-types
790 KlassDepChange(InstanceKlass* type) : _type(type) {
791 initialize();
792 }
793
794 // cleans up the marks
795 ~KlassDepChange();
796
797 public:
798 // What kind of DepChange is this?
799 virtual bool is_klass_change() const { return true; }
800
801 InstanceKlass* type() { return _type; }
802
803 // involves_context(k) is true if k == _type or any of its super types
804 bool involves_context(Klass* k);
805 };
806
807 // A class hierarchy change: new type is loaded.
808 class NewKlassDepChange : public KlassDepChange {
809 public:
810 NewKlassDepChange(InstanceKlass* new_type) : KlassDepChange(new_type) {}
811
812 // What kind of DepChange is this?
813 virtual bool is_new_klass_change() const { return true; }
814
815 InstanceKlass* new_type() { return type(); }
816 };
817
818 // Change in initialization state of a loaded class.
819 class KlassInitDepChange : public KlassDepChange {
820 public:
821 KlassInitDepChange(InstanceKlass* type) : KlassDepChange(type) {}
822
823 // What kind of DepChange is this?
824 virtual bool is_klass_init_change() const { return true; }
825 };
826
827 // A CallSite has changed its target.
828 class CallSiteDepChange : public DepChange {
829 private:
830 Handle _call_site;
831 Handle _method_handle;
832
833 public:
834 CallSiteDepChange(Handle call_site, Handle method_handle);
835
836 // What kind of DepChange is this?
837 virtual bool is_call_site_change() const { return true; }
838
839 oop call_site() const { return _call_site(); }
840 oop method_handle() const { return _method_handle(); }
841 };
842
843 #endif // SHARE_CODE_DEPENDENCIES_HPP