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annotate src/share/vm/code/dependencies.hpp @ 3500:6111c168756f
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author | Lukas Stadler <lukas.stadler@jku.at> |
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date | Mon, 08 Aug 2011 15:19:09 +0200 |
parents | f95d63e2154a |
children | fdb992d83a87 |
rev | line source |
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0 | 1 /* |
1972 | 2 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved. |
0 | 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. | |
18 * | |
1552
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
1972 | 25 #ifndef SHARE_VM_CODE_DEPENDENCIES_HPP |
26 #define SHARE_VM_CODE_DEPENDENCIES_HPP | |
27 | |
28 #include "ci/ciKlass.hpp" | |
29 #include "code/compressedStream.hpp" | |
30 #include "code/nmethod.hpp" | |
31 #include "utilities/growableArray.hpp" | |
32 | |
0 | 33 //** Dependencies represent assertions (approximate invariants) within |
34 // the class hierarchy. An example is an assertion that a given | |
35 // method is not overridden; another example is that a type has only | |
36 // one concrete subtype. Compiled code which relies on such | |
37 // assertions must be discarded if they are overturned by changes in | |
38 // the class hierarchy. We can think of these assertions as | |
39 // approximate invariants, because we expect them to be overturned | |
40 // very infrequently. We are willing to perform expensive recovery | |
41 // operations when they are overturned. The benefit, of course, is | |
42 // performing optimistic optimizations (!) on the object code. | |
43 // | |
44 // Changes in the class hierarchy due to dynamic linking or | |
45 // class evolution can violate dependencies. There is enough | |
46 // indexing between classes and nmethods to make dependency | |
47 // checking reasonably efficient. | |
48 | |
49 class ciEnv; | |
50 class nmethod; | |
51 class OopRecorder; | |
52 class xmlStream; | |
53 class CompileLog; | |
54 class DepChange; | |
55 class No_Safepoint_Verifier; | |
56 | |
57 class Dependencies: public ResourceObj { | |
58 public: | |
59 // Note: In the comments on dependency types, most uses of the terms | |
60 // subtype and supertype are used in a "non-strict" or "inclusive" | |
61 // sense, and are starred to remind the reader of this fact. | |
62 // Strict uses of the terms use the word "proper". | |
63 // | |
64 // Specifically, every class is its own subtype* and supertype*. | |
65 // (This trick is easier than continually saying things like "Y is a | |
66 // subtype of X or X itself".) | |
67 // | |
68 // Sometimes we write X > Y to mean X is a proper supertype of Y. | |
69 // The notation X > {Y, Z} means X has proper subtypes Y, Z. | |
70 // The notation X.m > Y means that Y inherits m from X, while | |
71 // X.m > Y.m means Y overrides X.m. A star denotes abstractness, | |
72 // as *I > A, meaning (abstract) interface I is a super type of A, | |
73 // or A.*m > B.m, meaning B.m implements abstract method A.m. | |
74 // | |
75 // In this module, the terms "subtype" and "supertype" refer to | |
76 // Java-level reference type conversions, as detected by | |
77 // "instanceof" and performed by "checkcast" operations. The method | |
78 // Klass::is_subtype_of tests these relations. Note that "subtype" | |
79 // is richer than "subclass" (as tested by Klass::is_subclass_of), | |
80 // since it takes account of relations involving interface and array | |
81 // types. | |
82 // | |
83 // To avoid needless complexity, dependencies involving array types | |
84 // are not accepted. If you need to make an assertion about an | |
85 // array type, make the assertion about its corresponding element | |
86 // types. Any assertion that might change about an array type can | |
87 // be converted to an assertion about its element type. | |
88 // | |
89 // Most dependencies are evaluated over a "context type" CX, which | |
90 // stands for the set Subtypes(CX) of every Java type that is a subtype* | |
91 // of CX. When the system loads a new class or interface N, it is | |
92 // responsible for re-evaluating changed dependencies whose context | |
93 // type now includes N, that is, all super types of N. | |
94 // | |
95 enum DepType { | |
96 end_marker = 0, | |
97 | |
98 // An 'evol' dependency simply notes that the contents of the | |
99 // method were used. If it evolves (is replaced), the nmethod | |
100 // must be recompiled. No other dependencies are implied. | |
101 evol_method, | |
102 FIRST_TYPE = evol_method, | |
103 | |
104 // A context type CX is a leaf it if has no proper subtype. | |
105 leaf_type, | |
106 | |
107 // An abstract class CX has exactly one concrete subtype CC. | |
108 abstract_with_unique_concrete_subtype, | |
109 | |
110 // The type CX is purely abstract, with no concrete subtype* at all. | |
111 abstract_with_no_concrete_subtype, | |
112 | |
113 // The concrete CX is free of concrete proper subtypes. | |
114 concrete_with_no_concrete_subtype, | |
115 | |
116 // Given a method M1 and a context class CX, the set MM(CX, M1) of | |
117 // "concrete matching methods" in CX of M1 is the set of every | |
118 // concrete M2 for which it is possible to create an invokevirtual | |
119 // or invokeinterface call site that can reach either M1 or M2. | |
120 // That is, M1 and M2 share a name, signature, and vtable index. | |
121 // We wish to notice when the set MM(CX, M1) is just {M1}, or | |
122 // perhaps a set of two {M1,M2}, and issue dependencies on this. | |
123 | |
124 // The set MM(CX, M1) can be computed by starting with any matching | |
125 // concrete M2 that is inherited into CX, and then walking the | |
126 // subtypes* of CX looking for concrete definitions. | |
127 | |
128 // The parameters to this dependency are the method M1 and the | |
129 // context class CX. M1 must be either inherited in CX or defined | |
130 // in a subtype* of CX. It asserts that MM(CX, M1) is no greater | |
131 // than {M1}. | |
132 unique_concrete_method, // one unique concrete method under CX | |
133 | |
134 // An "exclusive" assertion concerns two methods or subtypes, and | |
135 // declares that there are at most two (or perhaps later N>2) | |
136 // specific items that jointly satisfy the restriction. | |
137 // We list all items explicitly rather than just giving their | |
138 // count, for robustness in the face of complex schema changes. | |
139 | |
140 // A context class CX (which may be either abstract or concrete) | |
141 // has two exclusive concrete subtypes* C1, C2 if every concrete | |
142 // subtype* of CX is either C1 or C2. Note that if neither C1 or C2 | |
143 // are equal to CX, then CX itself must be abstract. But it is | |
144 // also possible (for example) that C1 is CX (a concrete class) | |
145 // and C2 is a proper subtype of C1. | |
146 abstract_with_exclusive_concrete_subtypes_2, | |
147 | |
148 // This dependency asserts that MM(CX, M1) is no greater than {M1,M2}. | |
149 exclusive_concrete_methods_2, | |
150 | |
151 // This dependency asserts that no instances of class or it's | |
152 // subclasses require finalization registration. | |
153 no_finalizable_subclasses, | |
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) & ((-1)<<FIRST_TYPE), | |
162 non_ctxk_types = (1<<evol_method), | |
163 ctxk_types = all_types & ~non_ctxk_types, | |
164 | |
165 max_arg_count = 3, // current maximum number of arguments (incl. ctxk) | |
166 | |
167 // A "context type" is a class or interface that | |
168 // provides context for evaluating a dependency. | |
169 // When present, it is one of the arguments (dep_context_arg). | |
170 // | |
171 // If a dependency does not have a context type, there is a | |
172 // default context, depending on the type of the dependency. | |
173 // This bit signals that a default context has been compressed away. | |
174 default_context_type_bit = (1<<LG2_TYPE_LIMIT) | |
175 }; | |
176 | |
177 static const char* dep_name(DepType dept); | |
178 static int dep_args(DepType dept); | |
179 static int dep_context_arg(DepType dept) { | |
180 return dept_in_mask(dept, ctxk_types)? 0: -1; | |
181 } | |
182 | |
183 private: | |
184 // State for writing a new set of dependencies: | |
185 GrowableArray<int>* _dep_seen; // (seen[h->ident] & (1<<dept)) | |
186 GrowableArray<ciObject*>* _deps[TYPE_LIMIT]; | |
187 | |
188 static const char* _dep_name[TYPE_LIMIT]; | |
189 static int _dep_args[TYPE_LIMIT]; | |
190 | |
191 static bool dept_in_mask(DepType dept, int mask) { | |
192 return (int)dept >= 0 && dept < TYPE_LIMIT && ((1<<dept) & mask) != 0; | |
193 } | |
194 | |
195 bool note_dep_seen(int dept, ciObject* x) { | |
196 assert(dept < BitsPerInt, "oob"); | |
197 int x_id = x->ident(); | |
198 assert(_dep_seen != NULL, "deps must be writable"); | |
199 int seen = _dep_seen->at_grow(x_id, 0); | |
200 _dep_seen->at_put(x_id, seen | (1<<dept)); | |
201 // return true if we've already seen dept/x | |
202 return (seen & (1<<dept)) != 0; | |
203 } | |
204 | |
205 bool maybe_merge_ctxk(GrowableArray<ciObject*>* deps, | |
206 int ctxk_i, ciKlass* ctxk); | |
207 | |
208 void sort_all_deps(); | |
209 size_t estimate_size_in_bytes(); | |
210 | |
211 // Initialize _deps, etc. | |
212 void initialize(ciEnv* env); | |
213 | |
214 // State for making a new set of dependencies: | |
215 OopRecorder* _oop_recorder; | |
216 | |
217 // Logging support | |
218 CompileLog* _log; | |
219 | |
220 address _content_bytes; // everything but the oop references, encoded | |
221 size_t _size_in_bytes; | |
222 | |
223 public: | |
224 // Make a new empty dependencies set. | |
225 Dependencies(ciEnv* env) { | |
226 initialize(env); | |
227 } | |
228 | |
229 private: | |
230 // Check for a valid context type. | |
231 // Enforce the restriction against array types. | |
232 static void check_ctxk(ciKlass* ctxk) { | |
233 assert(ctxk->is_instance_klass(), "java types only"); | |
234 } | |
235 static void check_ctxk_concrete(ciKlass* ctxk) { | |
236 assert(is_concrete_klass(ctxk->as_instance_klass()), "must be concrete"); | |
237 } | |
238 static void check_ctxk_abstract(ciKlass* ctxk) { | |
239 check_ctxk(ctxk); | |
240 assert(!is_concrete_klass(ctxk->as_instance_klass()), "must be abstract"); | |
241 } | |
242 | |
243 void assert_common_1(DepType dept, ciObject* x); | |
244 void assert_common_2(DepType dept, ciKlass* ctxk, ciObject* x); | |
245 void assert_common_3(DepType dept, ciKlass* ctxk, ciObject* x, ciObject* x2); | |
246 | |
247 public: | |
248 // Adding assertions to a new dependency set at compile time: | |
249 void assert_evol_method(ciMethod* m); | |
250 void assert_leaf_type(ciKlass* ctxk); | |
251 void assert_abstract_with_unique_concrete_subtype(ciKlass* ctxk, ciKlass* conck); | |
252 void assert_abstract_with_no_concrete_subtype(ciKlass* ctxk); | |
253 void assert_concrete_with_no_concrete_subtype(ciKlass* ctxk); | |
254 void assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm); | |
255 void assert_abstract_with_exclusive_concrete_subtypes(ciKlass* ctxk, ciKlass* k1, ciKlass* k2); | |
256 void assert_exclusive_concrete_methods(ciKlass* ctxk, ciMethod* m1, ciMethod* m2); | |
257 void assert_has_no_finalizable_subclasses(ciKlass* ctxk); | |
258 | |
259 // Define whether a given method or type is concrete. | |
260 // These methods define the term "concrete" as used in this module. | |
261 // For this module, an "abstract" class is one which is non-concrete. | |
262 // | |
263 // Future optimizations may allow some classes to remain | |
264 // non-concrete until their first instantiation, and allow some | |
265 // methods to remain non-concrete until their first invocation. | |
266 // In that case, there would be a middle ground between concrete | |
267 // and abstract (as defined by the Java language and VM). | |
268 static bool is_concrete_klass(klassOop k); // k is instantiable | |
269 static bool is_concrete_method(methodOop m); // m is invocable | |
270 static Klass* find_finalizable_subclass(Klass* k); | |
271 | |
272 // These versions of the concreteness queries work through the CI. | |
273 // The CI versions are allowed to skew sometimes from the VM | |
274 // (oop-based) versions. The cost of such a difference is a | |
275 // (safely) aborted compilation, or a deoptimization, or a missed | |
276 // optimization opportunity. | |
277 // | |
278 // In order to prevent spurious assertions, query results must | |
279 // remain stable within any single ciEnv instance. (I.e., they must | |
280 // not go back into the VM to get their value; they must cache the | |
281 // bit in the CI, either eagerly or lazily.) | |
282 static bool is_concrete_klass(ciInstanceKlass* k); // k appears instantiable | |
283 static bool is_concrete_method(ciMethod* m); // m appears invocable | |
284 static bool has_finalizable_subclass(ciInstanceKlass* k); | |
285 | |
286 // As a general rule, it is OK to compile under the assumption that | |
287 // a given type or method is concrete, even if it at some future | |
288 // point becomes abstract. So dependency checking is one-sided, in | |
289 // that it permits supposedly concrete classes or methods to turn up | |
290 // as really abstract. (This shouldn't happen, except during class | |
291 // evolution, but that's the logic of the checking.) However, if a | |
292 // supposedly abstract class or method suddenly becomes concrete, a | |
293 // dependency on it must fail. | |
294 | |
295 // Checking old assertions at run-time (in the VM only): | |
296 static klassOop check_evol_method(methodOop m); | |
297 static klassOop check_leaf_type(klassOop ctxk); | |
298 static klassOop check_abstract_with_unique_concrete_subtype(klassOop ctxk, klassOop conck, | |
299 DepChange* changes = NULL); | |
300 static klassOop check_abstract_with_no_concrete_subtype(klassOop ctxk, | |
301 DepChange* changes = NULL); | |
302 static klassOop check_concrete_with_no_concrete_subtype(klassOop ctxk, | |
303 DepChange* changes = NULL); | |
304 static klassOop check_unique_concrete_method(klassOop ctxk, methodOop uniqm, | |
305 DepChange* changes = NULL); | |
306 static klassOop check_abstract_with_exclusive_concrete_subtypes(klassOop ctxk, klassOop k1, klassOop k2, | |
307 DepChange* changes = NULL); | |
308 static klassOop check_exclusive_concrete_methods(klassOop ctxk, methodOop m1, methodOop m2, | |
309 DepChange* changes = NULL); | |
310 static klassOop check_has_no_finalizable_subclasses(klassOop ctxk, | |
311 DepChange* changes = NULL); | |
312 // A returned klassOop is NULL if the dependency assertion is still | |
313 // valid. A non-NULL klassOop is a 'witness' to the assertion | |
314 // failure, a point in the class hierarchy where the assertion has | |
315 // been proven false. For example, if check_leaf_type returns | |
316 // non-NULL, the value is a subtype of the supposed leaf type. This | |
317 // witness value may be useful for logging the dependency failure. | |
318 // Note that, when a dependency fails, there may be several possible | |
319 // witnesses to the failure. The value returned from the check_foo | |
320 // method is chosen arbitrarily. | |
321 | |
322 // The 'changes' value, if non-null, requests a limited spot-check | |
323 // near the indicated recent changes in the class hierarchy. | |
324 // It is used by DepStream::spot_check_dependency_at. | |
325 | |
326 // Detecting possible new assertions: | |
327 static klassOop find_unique_concrete_subtype(klassOop ctxk); | |
328 static methodOop find_unique_concrete_method(klassOop ctxk, methodOop m); | |
329 static int find_exclusive_concrete_subtypes(klassOop ctxk, int klen, klassOop k[]); | |
330 static int find_exclusive_concrete_methods(klassOop ctxk, int mlen, methodOop m[]); | |
331 | |
332 // Create the encoding which will be stored in an nmethod. | |
333 void encode_content_bytes(); | |
334 | |
335 address content_bytes() { | |
336 assert(_content_bytes != NULL, "encode it first"); | |
337 return _content_bytes; | |
338 } | |
339 size_t size_in_bytes() { | |
340 assert(_content_bytes != NULL, "encode it first"); | |
341 return _size_in_bytes; | |
342 } | |
343 | |
344 OopRecorder* oop_recorder() { return _oop_recorder; } | |
345 CompileLog* log() { return _log; } | |
346 | |
347 void copy_to(nmethod* nm); | |
348 | |
349 void log_all_dependencies(); | |
350 void log_dependency(DepType dept, int nargs, ciObject* args[]) { | |
351 write_dependency_to(log(), dept, nargs, args); | |
352 } | |
353 void log_dependency(DepType dept, | |
354 ciObject* x0, | |
355 ciObject* x1 = NULL, | |
356 ciObject* x2 = NULL) { | |
357 if (log() == NULL) return; | |
358 ciObject* args[max_arg_count]; | |
359 args[0] = x0; | |
360 args[1] = x1; | |
361 args[2] = x2; | |
362 assert(2 < max_arg_count, ""); | |
363 log_dependency(dept, dep_args(dept), args); | |
364 } | |
365 | |
366 static void write_dependency_to(CompileLog* log, | |
367 DepType dept, | |
368 int nargs, ciObject* args[], | |
369 klassOop witness = NULL); | |
370 static void write_dependency_to(CompileLog* log, | |
371 DepType dept, | |
372 int nargs, oop args[], | |
373 klassOop witness = NULL); | |
374 static void write_dependency_to(xmlStream* xtty, | |
375 DepType dept, | |
376 int nargs, oop args[], | |
377 klassOop witness = NULL); | |
378 static void print_dependency(DepType dept, | |
379 int nargs, oop args[], | |
380 klassOop witness = NULL); | |
381 | |
382 private: | |
383 // helper for encoding common context types as zero: | |
384 static ciKlass* ctxk_encoded_as_null(DepType dept, ciObject* x); | |
385 | |
386 static klassOop ctxk_encoded_as_null(DepType dept, oop x); | |
387 | |
388 public: | |
389 // Use this to iterate over an nmethod's dependency set. | |
390 // Works on new and old dependency sets. | |
391 // Usage: | |
392 // | |
393 // ; | |
394 // Dependencies::DepType dept; | |
395 // for (Dependencies::DepStream deps(nm); deps.next(); ) { | |
396 // ... | |
397 // } | |
398 // | |
399 // The caller must be in the VM, since oops are not wrapped in handles. | |
400 class DepStream { | |
401 private: | |
402 nmethod* _code; // null if in a compiler thread | |
403 Dependencies* _deps; // null if not in a compiler thread | |
404 CompressedReadStream _bytes; | |
405 #ifdef ASSERT | |
406 size_t _byte_limit; | |
407 #endif | |
408 | |
409 // iteration variables: | |
410 DepType _type; | |
411 int _xi[max_arg_count+1]; | |
412 | |
413 void initial_asserts(size_t byte_limit) NOT_DEBUG({}); | |
414 | |
415 inline oop recorded_oop_at(int i); | |
416 // => _code? _code->oop_at(i): *_deps->_oop_recorder->handle_at(i) | |
417 | |
418 klassOop check_dependency_impl(DepChange* changes); | |
419 | |
420 public: | |
421 DepStream(Dependencies* deps) | |
422 : _deps(deps), | |
423 _code(NULL), | |
424 _bytes(deps->content_bytes()) | |
425 { | |
426 initial_asserts(deps->size_in_bytes()); | |
427 } | |
428 DepStream(nmethod* code) | |
429 : _deps(NULL), | |
430 _code(code), | |
431 _bytes(code->dependencies_begin()) | |
432 { | |
433 initial_asserts(code->dependencies_size()); | |
434 } | |
435 | |
436 bool next(); | |
437 | |
438 DepType type() { return _type; } | |
439 int argument_count() { return dep_args(type()); } | |
440 int argument_index(int i) { assert(0 <= i && i < argument_count(), "oob"); | |
441 return _xi[i]; } | |
442 oop argument(int i); // => recorded_oop_at(argument_index(i)) | |
443 klassOop context_type(); | |
444 | |
445 methodOop method_argument(int i) { | |
446 oop x = argument(i); | |
447 assert(x->is_method(), "type"); | |
448 return (methodOop) x; | |
449 } | |
450 klassOop type_argument(int i) { | |
451 oop x = argument(i); | |
452 assert(x->is_klass(), "type"); | |
453 return (klassOop) x; | |
454 } | |
455 | |
456 // The point of the whole exercise: Is this dep is still OK? | |
457 klassOop check_dependency() { | |
458 return check_dependency_impl(NULL); | |
459 } | |
460 // A lighter version: Checks only around recent changes in a class | |
461 // hierarchy. (See Universe::flush_dependents_on.) | |
462 klassOop spot_check_dependency_at(DepChange& changes); | |
463 | |
464 // Log the current dependency to xtty or compilation log. | |
465 void log_dependency(klassOop witness = NULL); | |
466 | |
467 // Print the current dependency to tty. | |
468 void print_dependency(klassOop witness = NULL, bool verbose = false); | |
469 }; | |
470 friend class Dependencies::DepStream; | |
471 | |
472 static void print_statistics() PRODUCT_RETURN; | |
473 }; | |
474 | |
475 // A class hierarchy change coming through the VM (under the Compile_lock). | |
476 // The change is structured as a single new type with any number of supers | |
477 // and implemented interface types. Other than the new type, any of the | |
478 // super types can be context types for a relevant dependency, which the | |
479 // new type could invalidate. | |
480 class DepChange : public StackObj { | |
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481 public: |
0 | 482 enum ChangeType { |
483 NO_CHANGE = 0, // an uninvolved klass | |
484 Change_new_type, // a newly loaded type | |
485 Change_new_sub, // a super with a new subtype | |
486 Change_new_impl, // an interface with a new implementation | |
487 CHANGE_LIMIT, | |
488 Start_Klass = CHANGE_LIMIT // internal indicator for ContextStream | |
489 }; | |
490 | |
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491 private: |
0 | 492 // each change set is rooted in exactly one new type (at present): |
493 KlassHandle _new_type; | |
494 | |
495 void initialize(); | |
496 | |
497 public: | |
498 // notes the new type, marks it and all its super-types | |
499 DepChange(KlassHandle new_type) | |
500 : _new_type(new_type) | |
501 { | |
502 initialize(); | |
503 } | |
504 | |
505 // cleans up the marks | |
506 ~DepChange(); | |
507 | |
508 klassOop new_type() { return _new_type(); } | |
509 | |
510 // involves_context(k) is true if k is new_type or any of the super types | |
511 bool involves_context(klassOop k); | |
512 | |
513 // Usage: | |
514 // for (DepChange::ContextStream str(changes); str.next(); ) { | |
515 // klassOop k = str.klass(); | |
516 // switch (str.change_type()) { | |
517 // ... | |
518 // } | |
519 // } | |
520 class ContextStream : public StackObj { | |
521 private: | |
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522 DepChange& _changes; |
0 | 523 friend class DepChange; |
524 | |
525 // iteration variables: | |
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526 ChangeType _change_type; |
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527 klassOop _klass; |
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528 objArrayOop _ti_base; // i.e., transitive_interfaces |
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529 int _ti_index; |
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530 int _ti_limit; |
0 | 531 |
532 // start at the beginning: | |
533 void start() { | |
534 klassOop new_type = _changes.new_type(); | |
535 _change_type = (new_type == NULL ? NO_CHANGE: Start_Klass); | |
536 _klass = new_type; | |
537 _ti_base = NULL; | |
538 _ti_index = 0; | |
539 _ti_limit = 0; | |
540 } | |
541 | |
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542 public: |
0 | 543 ContextStream(DepChange& changes) |
544 : _changes(changes) | |
545 { start(); } | |
546 | |
547 ContextStream(DepChange& changes, No_Safepoint_Verifier& nsv) | |
548 : _changes(changes) | |
549 // the nsv argument makes it safe to hold oops like _klass | |
550 { start(); } | |
551 | |
552 bool next(); | |
553 | |
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554 ChangeType change_type() { return _change_type; } |
0 | 555 klassOop klass() { return _klass; } |
556 }; | |
557 friend class DepChange::ContextStream; | |
558 | |
559 void print(); | |
560 }; | |
1972 | 561 |
562 #endif // SHARE_VM_CODE_DEPENDENCIES_HPP |