1 /*
2 * Copyright (c) 2005, 2018, 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 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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23 */
24
25 #ifndef SHARE_VM_CODE_DEPENDENCIES_HPP
26 #define SHARE_VM_CODE_DEPENDENCIES_HPP
27
28 #include "ci/ciCallSite.hpp"
29 #include "ci/ciKlass.hpp"
30 #include "ci/ciMethodHandle.hpp"
31 #include "classfile/systemDictionary.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 #include "utilities/hashtable.hpp"
38
39 //** Dependencies represent assertions (approximate invariants) within
40 // the runtime system, e.g. class hierarchy changes. An example is an
41 // assertion that a given method is not overridden; another example is
42 // that a type has only one concrete subtype. Compiled code which
43 // relies on such assertions must be discarded if they are overturned
44 // by changes in the runtime system. We can think of these assertions
45 // as approximate invariants, because we expect them to be overturned
46 // very infrequently. We are willing to perform expensive recovery
47 // operations when they are overturned. The benefit, of course, is
48 // performing optimistic optimizations (!) on the object code.
49 //
50 // Changes in the class hierarchy due to dynamic linking or
51 // class evolution can violate dependencies. There is enough
52 // indexing between classes and nmethods to make dependency
53 // checking reasonably efficient.
54
55 class ciEnv;
56 class nmethod;
57 class OopRecorder;
58 class xmlStream;
59 class CompileLog;
60 class DepChange;
61 class KlassDepChange;
62 class CallSiteDepChange;
63 class NoSafepointVerifier;
64
65 class Dependencies: public ResourceObj {
66 public:
67 // Note: In the comments on dependency types, most uses of the terms
68 // subtype and supertype are used in a "non-strict" or "inclusive"
69 // sense, and are starred to remind the reader of this fact.
70 // Strict uses of the terms use the word "proper".
71 //
72 // Specifically, every class is its own subtype* and supertype*.
73 // (This trick is easier than continually saying things like "Y is a
74 // subtype of X or X itself".)
75 //
76 // Sometimes we write X > Y to mean X is a proper supertype of Y.
77 // The notation X > {Y, Z} means X has proper subtypes Y, Z.
78 // The notation X.m > Y means that Y inherits m from X, while
79 // X.m > Y.m means Y overrides X.m. A star denotes abstractness,
80 // as *I > A, meaning (abstract) interface I is a super type of A,
81 // or A.*m > B.m, meaning B.m implements abstract method A.m.
82 //
83 // In this module, the terms "subtype" and "supertype" refer to
84 // Java-level reference type conversions, as detected by
85 // "instanceof" and performed by "checkcast" operations. The method
86 // Klass::is_subtype_of tests these relations. Note that "subtype"
87 // is richer than "subclass" (as tested by Klass::is_subclass_of),
88 // since it takes account of relations involving interface and array
89 // types.
90 //
91 // To avoid needless complexity, dependencies involving array types
92 // are not accepted. If you need to make an assertion about an
93 // array type, make the assertion about its corresponding element
94 // types. Any assertion that might change about an array type can
95 // be converted to an assertion about its element type.
96 //
97 // Most dependencies are evaluated over a "context type" CX, which
98 // stands for the set Subtypes(CX) of every Java type that is a subtype*
99 // of CX. When the system loads a new class or interface N, it is
100 // responsible for re-evaluating changed dependencies whose context
101 // type now includes N, that is, all super types of N.
102 //
103 enum DepType {
104 end_marker = 0,
105
106 // An 'evol' dependency simply notes that the contents of the
107 // method were used. If it evolves (is replaced), the nmethod
108 // must be recompiled. No other dependencies are implied.
109 evol_method,
110 FIRST_TYPE = evol_method,
111
112 // A context type CX is a leaf it if has no proper subtype.
113 leaf_type,
114
115 // An abstract class CX has exactly one concrete subtype CC.
116 abstract_with_unique_concrete_subtype,
117
118 // The type CX is purely abstract, with no concrete subtype* at all.
119 abstract_with_no_concrete_subtype,
120
121 // The concrete CX is free of concrete proper subtypes.
122 concrete_with_no_concrete_subtype,
123
124 // Given a method M1 and a context class CX, the set MM(CX, M1) of
125 // "concrete matching methods" in CX of M1 is the set of every
126 // concrete M2 for which it is possible to create an invokevirtual
127 // or invokeinterface call site that can reach either M1 or M2.
128 // That is, M1 and M2 share a name, signature, and vtable index.
129 // We wish to notice when the set MM(CX, M1) is just {M1}, or
130 // perhaps a set of two {M1,M2}, and issue dependencies on this.
131
132 // The set MM(CX, M1) can be computed by starting with any matching
133 // concrete M2 that is inherited into CX, and then walking the
134 // subtypes* of CX looking for concrete definitions.
135
136 // The parameters to this dependency are the method M1 and the
137 // context class CX. M1 must be either inherited in CX or defined
138 // in a subtype* of CX. It asserts that MM(CX, M1) is no greater
139 // than {M1}.
140 unique_concrete_method, // one unique concrete method under CX
141
142 // An "exclusive" assertion concerns two methods or subtypes, and
143 // declares that there are at most two (or perhaps later N>2)
144 // specific items that jointly satisfy the restriction.
145 // We list all items explicitly rather than just giving their
146 // count, for robustness in the face of complex schema changes.
147
148 // A context class CX (which may be either abstract or concrete)
149 // has two exclusive concrete subtypes* C1, C2 if every concrete
150 // subtype* of CX is either C1 or C2. Note that if neither C1 or C2
151 // are equal to CX, then CX itself must be abstract. But it is
152 // also possible (for example) that C1 is CX (a concrete class)
153 // and C2 is a proper subtype of C1.
154 abstract_with_exclusive_concrete_subtypes_2,
155
156 // This dependency asserts that MM(CX, M1) is no greater than {M1,M2}.
157 exclusive_concrete_methods_2,
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 << 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 = 3, // 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
193 static const char* dep_name(DepType dept);
194 static int dep_args(DepType dept);
195
196 static bool is_klass_type( DepType dept) { return dept_in_mask(dept, klass_types ); }
197
198 static bool has_explicit_context_arg(DepType dept) { return dept_in_mask(dept, explicit_ctxk_types); }
199 static bool has_implicit_context_arg(DepType dept) { return dept_in_mask(dept, implicit_ctxk_types); }
200
201 static int dep_context_arg(DepType dept) { return has_explicit_context_arg(dept) ? 0 : -1; }
202 static int dep_implicit_context_arg(DepType dept) { return has_implicit_context_arg(dept) ? 0 : -1; }
203
204 static void check_valid_dependency_type(DepType dept);
205
206 #if INCLUDE_JVMCI
207 // A Metadata* or object value recorded in an OopRecorder
208 class DepValue {
209 private:
210 // Unique identifier of the value within the associated OopRecorder that
211 // encodes both the category of the value (0: invalid, positive: metadata, negative: object)
212 // and the index within a category specific array (metadata: index + 1, object: -(index + 1))
213 int _id;
214
215 public:
216 DepValue() : _id(0) {}
217 DepValue(OopRecorder* rec, Metadata* metadata, DepValue* candidate = NULL) {
218 assert(candidate == NULL || candidate->is_metadata(), "oops");
219 if (candidate != NULL && candidate->as_metadata(rec) == metadata) {
220 _id = candidate->_id;
221 } else {
222 _id = rec->find_index(metadata) + 1;
223 }
224 }
225 DepValue(OopRecorder* rec, jobject obj, DepValue* candidate = NULL) {
226 assert(candidate == NULL || candidate->is_object(), "oops");
227 if (candidate != NULL && candidate->as_object(rec) == obj) {
228 _id = candidate->_id;
229 } else {
230 _id = -(rec->find_index(obj) + 1);
231 }
232 }
233
234 // Used to sort values in ascending order of index() with metadata values preceding object values
235 int sort_key() const { return -_id; }
236
237 bool operator == (const DepValue& other) const { return other._id == _id; }
238
239 bool is_valid() const { return _id != 0; }
240 int index() const { assert(is_valid(), "oops"); return _id < 0 ? -(_id + 1) : _id - 1; }
241 bool is_metadata() const { assert(is_valid(), "oops"); return _id > 0; }
242 bool is_object() const { assert(is_valid(), "oops"); return _id < 0; }
243
244 Metadata* as_metadata(OopRecorder* rec) const { assert(is_metadata(), "oops"); return rec->metadata_at(index()); }
245 Klass* as_klass(OopRecorder* rec) const {
246 Metadata* m = as_metadata(rec);
247 assert(m != NULL, "as_metadata returned NULL");
248 assert(m->is_klass(), "oops");
249 return (Klass*) m;
250 }
251 Method* as_method(OopRecorder* rec) const {
252 Metadata* m = as_metadata(rec);
253 assert(m != NULL, "as_metadata returned NULL");
254 assert(m->is_method(), "oops");
255 return (Method*) m;
256 }
257 jobject as_object(OopRecorder* rec) const { assert(is_object(), "oops"); return rec->oop_at(index()); }
258 };
259 #endif // INCLUDE_JVMCI
260
261 private:
262 // State for writing a new set of dependencies:
263 GrowableArray<int>* _dep_seen; // (seen[h->ident] & (1<<dept))
264 GrowableArray<ciBaseObject*>* _deps[TYPE_LIMIT];
265 #if INCLUDE_JVMCI
266 bool _using_dep_values;
267 GrowableArray<DepValue>* _dep_values[TYPE_LIMIT];
268 #endif
269
270 static const char* _dep_name[TYPE_LIMIT];
271 static int _dep_args[TYPE_LIMIT];
272
273 static bool dept_in_mask(DepType dept, int mask) {
274 return (int)dept >= 0 && dept < TYPE_LIMIT && ((1<<dept) & mask) != 0;
275 }
276
277 bool note_dep_seen(int dept, ciBaseObject* x) {
278 assert(dept < BitsPerInt, "oob");
279 int x_id = x->ident();
280 assert(_dep_seen != NULL, "deps must be writable");
281 int seen = _dep_seen->at_grow(x_id, 0);
282 _dep_seen->at_put(x_id, seen | (1<<dept));
283 // return true if we've already seen dept/x
284 return (seen & (1<<dept)) != 0;
285 }
286
287 #if INCLUDE_JVMCI
288 bool note_dep_seen(int dept, DepValue x) {
289 assert(dept < BitsPerInt, "oops");
290 // place metadata deps at even indexes, object deps at odd indexes
291 int x_id = x.is_metadata() ? x.index() * 2 : (x.index() * 2) + 1;
292 assert(_dep_seen != NULL, "deps must be writable");
293 int seen = _dep_seen->at_grow(x_id, 0);
294 _dep_seen->at_put(x_id, seen | (1<<dept));
295 // return true if we've already seen dept/x
296 return (seen & (1<<dept)) != 0;
297 }
298 #endif
299
300 bool maybe_merge_ctxk(GrowableArray<ciBaseObject*>* deps,
301 int ctxk_i, ciKlass* ctxk);
302 #if INCLUDE_JVMCI
303 bool maybe_merge_ctxk(GrowableArray<DepValue>* deps,
304 int ctxk_i, DepValue ctxk);
305 #endif
306
307 void sort_all_deps();
308 size_t estimate_size_in_bytes();
309
310 // Initialize _deps, etc.
311 void initialize(ciEnv* env);
312
313 // State for making a new set of dependencies:
314 OopRecorder* _oop_recorder;
315
316 // Logging support
317 CompileLog* _log;
318
319 address _content_bytes; // everything but the oop references, encoded
320 size_t _size_in_bytes;
321
322 public:
323 // Make a new empty dependencies set.
324 Dependencies(ciEnv* env) {
325 initialize(env);
326 }
327 #if INCLUDE_JVMCI
328 Dependencies(Arena* arena, OopRecorder* oop_recorder, CompileLog* log);
329 #endif
330
331 private:
332 // Check for a valid context type.
333 // Enforce the restriction against array types.
334 static void check_ctxk(ciKlass* ctxk) {
335 assert(ctxk->is_instance_klass(), "java types only");
336 }
337 static void check_ctxk_concrete(ciKlass* ctxk) {
338 assert(is_concrete_klass(ctxk->as_instance_klass()), "must be concrete");
339 }
340 static void check_ctxk_abstract(ciKlass* ctxk) {
341 check_ctxk(ctxk);
342 assert(!is_concrete_klass(ctxk->as_instance_klass()), "must be abstract");
343 }
344
345 void assert_common_1(DepType dept, ciBaseObject* x);
346 void assert_common_2(DepType dept, ciBaseObject* x0, ciBaseObject* x1);
347 void assert_common_3(DepType dept, ciKlass* ctxk, ciBaseObject* x1, ciBaseObject* x2);
348
349 public:
350 // Adding assertions to a new dependency set at compile time:
351 void assert_evol_method(ciMethod* m);
352 void assert_leaf_type(ciKlass* ctxk);
353 void assert_abstract_with_unique_concrete_subtype(ciKlass* ctxk, ciKlass* conck);
354 void assert_abstract_with_no_concrete_subtype(ciKlass* ctxk);
355 void assert_concrete_with_no_concrete_subtype(ciKlass* ctxk);
356 void assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm);
357 void assert_abstract_with_exclusive_concrete_subtypes(ciKlass* ctxk, ciKlass* k1, ciKlass* k2);
358 void assert_exclusive_concrete_methods(ciKlass* ctxk, ciMethod* m1, ciMethod* m2);
359 void assert_has_no_finalizable_subclasses(ciKlass* ctxk);
360 void assert_call_site_target_value(ciCallSite* call_site, ciMethodHandle* method_handle);
361
362 #if INCLUDE_JVMCI
363 private:
364 static void check_ctxk(Klass* ctxk) {
365 assert(ctxk->is_instance_klass(), "java types only");
366 }
367 static void check_ctxk_abstract(Klass* ctxk) {
368 check_ctxk(ctxk);
369 assert(ctxk->is_abstract(), "must be abstract");
370 }
371 void assert_common_1(DepType dept, DepValue x);
372 void assert_common_2(DepType dept, DepValue x0, DepValue x1);
373
374 public:
375 void assert_evol_method(Method* m);
376 void assert_has_no_finalizable_subclasses(Klass* ctxk);
377 void assert_leaf_type(Klass* ctxk);
378 void assert_unique_concrete_method(Klass* ctxk, Method* uniqm);
379 void assert_abstract_with_unique_concrete_subtype(Klass* ctxk, Klass* conck);
380 void assert_call_site_target_value(oop callSite, oop methodHandle);
381 #endif // INCLUDE_JVMCI
382
383 // Define whether a given method or type is concrete.
384 // These methods define the term "concrete" as used in this module.
385 // For this module, an "abstract" class is one which is non-concrete.
386 //
387 // Future optimizations may allow some classes to remain
388 // non-concrete until their first instantiation, and allow some
389 // methods to remain non-concrete until their first invocation.
390 // In that case, there would be a middle ground between concrete
391 // and abstract (as defined by the Java language and VM).
392 static bool is_concrete_klass(Klass* k); // k is instantiable
393 static bool is_concrete_method(Method* m, Klass* k); // m is invocable
394 static Klass* find_finalizable_subclass(Klass* k);
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(Klass* ctxk);
421 static Klass* check_abstract_with_unique_concrete_subtype(Klass* ctxk, Klass* conck,
422 KlassDepChange* changes = NULL);
423 static Klass* check_abstract_with_no_concrete_subtype(Klass* ctxk,
424 KlassDepChange* changes = NULL);
425 static Klass* check_concrete_with_no_concrete_subtype(Klass* ctxk,
426 KlassDepChange* changes = NULL);
427 static Klass* check_unique_concrete_method(Klass* ctxk, Method* uniqm,
428 KlassDepChange* changes = NULL);
429 static Klass* check_abstract_with_exclusive_concrete_subtypes(Klass* ctxk, Klass* k1, Klass* k2,
430 KlassDepChange* changes = NULL);
431 static Klass* check_exclusive_concrete_methods(Klass* ctxk, Method* m1, Method* m2,
432 KlassDepChange* changes = NULL);
433 static Klass* check_has_no_finalizable_subclasses(Klass* ctxk, KlassDepChange* changes = NULL);
434 static Klass* check_call_site_target_value(oop call_site, oop method_handle, CallSiteDepChange* changes = NULL);
435 // A returned Klass* is NULL if the dependency assertion is still
436 // valid. A non-NULL Klass* is a 'witness' to the assertion
437 // failure, a point in the class hierarchy where the assertion has
438 // been proven false. For example, if check_leaf_type returns
439 // non-NULL, the value is a subtype of the supposed leaf type. This
440 // witness value may be useful for logging the dependency failure.
441 // Note that, when a dependency fails, there may be several possible
442 // witnesses to the failure. The value returned from the check_foo
443 // method is chosen arbitrarily.
444
445 // The 'changes' value, if non-null, requests a limited spot-check
446 // near the indicated recent changes in the class hierarchy.
447 // It is used by DepStream::spot_check_dependency_at.
448
449 // Detecting possible new assertions:
450 static Klass* find_unique_concrete_subtype(Klass* ctxk);
451 static Method* find_unique_concrete_method(Klass* ctxk, Method* m);
452 static int find_exclusive_concrete_subtypes(Klass* ctxk, int klen, Klass* k[]);
453
454 // Create the encoding which will be stored in an nmethod.
455 void encode_content_bytes();
456
457 address content_bytes() {
458 assert(_content_bytes != NULL, "encode it first");
459 return _content_bytes;
460 }
461 size_t size_in_bytes() {
462 assert(_content_bytes != NULL, "encode it first");
463 return _size_in_bytes;
464 }
465
466 OopRecorder* oop_recorder() { return _oop_recorder; }
467 CompileLog* log() { return _log; }
468
469 void copy_to(nmethod* nm);
470
471 DepType validate_dependencies(CompileTask* task, bool counter_changed, char** failure_detail = NULL);
472
473 void log_all_dependencies();
474
475 void log_dependency(DepType dept, GrowableArray<ciBaseObject*>* args) {
476 ResourceMark rm;
477 int argslen = args->length();
478 write_dependency_to(log(), dept, args);
479 guarantee(argslen == args->length(),
480 "args array cannot grow inside nested ResoureMark scope");
481 }
482
483 void log_dependency(DepType dept,
484 ciBaseObject* x0,
485 ciBaseObject* x1 = NULL,
486 ciBaseObject* x2 = NULL) {
487 if (log() == NULL) {
488 return;
489 }
490 ResourceMark rm;
491 GrowableArray<ciBaseObject*>* ciargs =
492 new GrowableArray<ciBaseObject*>(dep_args(dept));
493 assert (x0 != NULL, "no log x0");
494 ciargs->push(x0);
495
496 if (x1 != NULL) {
497 ciargs->push(x1);
498 }
499 if (x2 != NULL) {
500 ciargs->push(x2);
501 }
502 assert(ciargs->length() == dep_args(dept), "");
503 log_dependency(dept, ciargs);
504 }
505
506 class DepArgument : public ResourceObj {
507 private:
508 bool _is_oop;
509 bool _valid;
510 void* _value;
511 public:
512 DepArgument() : _is_oop(false), _value(NULL), _valid(false) {}
513 DepArgument(oop v): _is_oop(true), _value(v), _valid(true) {}
514 DepArgument(Metadata* v): _is_oop(false), _value(v), _valid(true) {}
515
516 bool is_null() const { return _value == NULL; }
517 bool is_oop() const { return _is_oop; }
518 bool is_metadata() const { return !_is_oop; }
519 bool is_klass() const { return is_metadata() && metadata_value()->is_klass(); }
520 bool is_method() const { return is_metadata() && metadata_value()->is_method(); }
521
522 oop oop_value() const { assert(_is_oop && _valid, "must be"); return (oop) _value; }
523 Metadata* metadata_value() const { assert(!_is_oop && _valid, "must be"); return (Metadata*) _value; }
524 };
525
526 static void print_dependency(DepType dept,
527 GrowableArray<DepArgument>* args,
528 Klass* witness = NULL, outputStream* st = tty);
529
530 private:
531 // helper for encoding common context types as zero:
532 static ciKlass* ctxk_encoded_as_null(DepType dept, ciBaseObject* x);
533
534 static Klass* ctxk_encoded_as_null(DepType dept, Metadata* x);
535
536 static void write_dependency_to(CompileLog* log,
537 DepType dept,
538 GrowableArray<ciBaseObject*>* args,
539 Klass* witness = NULL);
540 static void write_dependency_to(CompileLog* log,
541 DepType dept,
542 GrowableArray<DepArgument>* args,
543 Klass* witness = NULL);
544 static void write_dependency_to(xmlStream* xtty,
545 DepType dept,
546 GrowableArray<DepArgument>* args,
547 Klass* witness = NULL);
548 public:
549 // Use this to iterate over an nmethod's dependency set.
550 // Works on new and old dependency sets.
551 // Usage:
552 //
553 // ;
554 // Dependencies::DepType dept;
555 // for (Dependencies::DepStream deps(nm); deps.next(); ) {
556 // ...
557 // }
558 //
559 // The caller must be in the VM, since oops are not wrapped in handles.
560 class DepStream {
561 private:
562 nmethod* _code; // null if in a compiler thread
563 Dependencies* _deps; // null if not in a compiler thread
564 CompressedReadStream _bytes;
565 #ifdef ASSERT
566 size_t _byte_limit;
567 #endif
568
569 // iteration variables:
570 DepType _type;
571 int _xi[max_arg_count+1];
572
573 void initial_asserts(size_t byte_limit) NOT_DEBUG({});
574
575 inline Metadata* recorded_metadata_at(int i);
576 inline oop recorded_oop_at(int i);
577
578 Klass* check_klass_dependency(KlassDepChange* changes);
579 Klass* check_call_site_dependency(CallSiteDepChange* changes);
580
581 void trace_and_log_witness(Klass* witness);
582
583 public:
584 DepStream(Dependencies* deps)
585 : _deps(deps),
586 _code(NULL),
587 _bytes(deps->content_bytes())
588 {
589 initial_asserts(deps->size_in_bytes());
590 }
591 DepStream(nmethod* code)
592 : _deps(NULL),
593 _code(code),
594 _bytes(code->dependencies_begin())
595 {
596 initial_asserts(code->dependencies_size());
597 }
598
599 bool next();
600
601 DepType type() { return _type; }
602 bool is_oop_argument(int i) { return type() == call_site_target_value; }
603 uintptr_t get_identifier(int i);
604
605 int argument_count() { return dep_args(type()); }
606 int argument_index(int i) { assert(0 <= i && i < argument_count(), "oob");
607 return _xi[i]; }
608 Metadata* argument(int i); // => recorded_oop_at(argument_index(i))
609 oop argument_oop(int i); // => recorded_oop_at(argument_index(i))
610 Klass* context_type();
611
612 bool is_klass_type() { return Dependencies::is_klass_type(type()); }
613
614 Method* method_argument(int i) {
615 Metadata* x = argument(i);
616 assert(x->is_method(), "type");
617 return (Method*) x;
618 }
619 Klass* type_argument(int i) {
620 Metadata* x = argument(i);
621 assert(x->is_klass(), "type");
622 return (Klass*) x;
623 }
624
625 // The point of the whole exercise: Is this dep still OK?
626 Klass* check_dependency() {
627 Klass* result = check_klass_dependency(NULL);
628 if (result != NULL) return result;
629 return check_call_site_dependency(NULL);
630 }
631
632 // A lighter version: Checks only around recent changes in a class
633 // hierarchy. (See Universe::flush_dependents_on.)
634 Klass* spot_check_dependency_at(DepChange& changes);
635
636 // Log the current dependency to xtty or compilation log.
637 void log_dependency(Klass* witness = NULL);
638
639 // Print the current dependency to tty.
640 void print_dependency(Klass* witness = NULL, bool verbose = false, outputStream* st = tty);
641 };
642 friend class Dependencies::DepStream;
643
644 static void print_statistics() PRODUCT_RETURN;
645 };
646
647
648 class DependencySignature : public ResourceObj {
649 private:
650 int _args_count;
651 uintptr_t _argument_hash[Dependencies::max_arg_count];
652 Dependencies::DepType _type;
653
654 public:
655 DependencySignature(Dependencies::DepStream& dep) {
656 _args_count = dep.argument_count();
657 _type = dep.type();
658 for (int i = 0; i < _args_count; i++) {
659 _argument_hash[i] = dep.get_identifier(i);
660 }
661 }
662
663 static bool equals(DependencySignature const& s1, DependencySignature const& s2);
664 static unsigned hash (DependencySignature const& s1) { return s1.arg(0) >> 2; }
665
666 int args_count() const { return _args_count; }
667 uintptr_t arg(int idx) const { return _argument_hash[idx]; }
668 Dependencies::DepType type() const { return _type; }
669
670 };
671
672
673 // Every particular DepChange is a sub-class of this class.
674 class DepChange : public StackObj {
675 public:
676 // What kind of DepChange is this?
677 virtual bool is_klass_change() const { return false; }
678 virtual bool is_call_site_change() const { return false; }
679
680 virtual void mark_for_deoptimization(nmethod* nm) = 0;
681
682 // Subclass casting with assertions.
683 KlassDepChange* as_klass_change() {
684 assert(is_klass_change(), "bad cast");
685 return (KlassDepChange*) this;
686 }
687 CallSiteDepChange* as_call_site_change() {
688 assert(is_call_site_change(), "bad cast");
689 return (CallSiteDepChange*) this;
690 }
691
692 void print();
693
694 public:
695 enum ChangeType {
696 NO_CHANGE = 0, // an uninvolved klass
697 Change_new_type, // a newly loaded type
698 Change_new_sub, // a super with a new subtype
699 Change_new_impl, // an interface with a new implementation
700 CHANGE_LIMIT,
701 Start_Klass = CHANGE_LIMIT // internal indicator for ContextStream
702 };
703
704 // Usage:
705 // for (DepChange::ContextStream str(changes); str.next(); ) {
706 // Klass* k = str.klass();
707 // switch (str.change_type()) {
708 // ...
709 // }
710 // }
711 class ContextStream : public StackObj {
712 private:
713 DepChange& _changes;
714 friend class DepChange;
715
716 // iteration variables:
717 ChangeType _change_type;
718 Klass* _klass;
719 Array<Klass*>* _ti_base; // i.e., transitive_interfaces
720 int _ti_index;
721 int _ti_limit;
722
723 // start at the beginning:
724 void start();
725
726 public:
727 ContextStream(DepChange& changes)
728 : _changes(changes)
729 { start(); }
730
731 ContextStream(DepChange& changes, NoSafepointVerifier& nsv)
732 : _changes(changes)
733 // the nsv argument makes it safe to hold oops like _klass
734 { start(); }
735
736 bool next();
737
738 ChangeType change_type() { return _change_type; }
739 Klass* klass() { return _klass; }
740 };
741 friend class DepChange::ContextStream;
742 };
743
744
745 // A class hierarchy change coming through the VM (under the Compile_lock).
746 // The change is structured as a single new type with any number of supers
747 // and implemented interface types. Other than the new type, any of the
748 // super types can be context types for a relevant dependency, which the
749 // new type could invalidate.
750 class KlassDepChange : public DepChange {
751 private:
752 // each change set is rooted in exactly one new type (at present):
753 Klass* _new_type;
754
755 void initialize();
756
757 public:
758 // notes the new type, marks it and all its super-types
759 KlassDepChange(Klass* new_type)
760 : _new_type(new_type)
761 {
762 initialize();
763 }
764
765 // cleans up the marks
766 ~KlassDepChange();
767
768 // What kind of DepChange is this?
769 virtual bool is_klass_change() const { return true; }
770
771 virtual void mark_for_deoptimization(nmethod* nm) {
772 nm->mark_for_deoptimization(/*inc_recompile_counts=*/true);
773 }
774
775 Klass* new_type() { return _new_type; }
776
777 // involves_context(k) is true if k is new_type or any of the super types
778 bool involves_context(Klass* k);
779 };
780
781
782 // A CallSite has changed its target.
783 class CallSiteDepChange : public DepChange {
784 private:
785 Handle _call_site;
786 Handle _method_handle;
787
788 public:
789 CallSiteDepChange(Handle call_site, Handle method_handle);
790
791 // What kind of DepChange is this?
792 virtual bool is_call_site_change() const { return true; }
793
794 virtual void mark_for_deoptimization(nmethod* nm) {
795 nm->mark_for_deoptimization(/*inc_recompile_counts=*/false);
796 }
797
798 oop call_site() const { return _call_site(); }
799 oop method_handle() const { return _method_handle(); }
800 };
801
802 #endif // SHARE_VM_CODE_DEPENDENCIES_HPP