Mon, 25 Jun 2012 21:33:35 -0400
7178670: runtime/7158800/BadUtf8.java fails in SymbolTable::rehash_table
Summary: Cannot delete _buckets and HashtableEntries in shared space (CDS)
Reviewed-by: acorn, kvn, dlong, dcubed, kamg
1 /*
2 * Copyright (c) 2005, 2011, 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.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
25 #ifndef SHARE_VM_CODE_DEPENDENCIES_HPP
26 #define SHARE_VM_CODE_DEPENDENCIES_HPP
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 "utilities/growableArray.hpp"
36 //** Dependencies represent assertions (approximate invariants) within
37 // the runtime system, e.g. class hierarchy changes. An example is an
38 // assertion that a given method is not overridden; another example is
39 // that a type has only one concrete subtype. Compiled code which
40 // relies on such assertions must be discarded if they are overturned
41 // by changes in the runtime system. We can think of these assertions
42 // as approximate invariants, because we expect them to be overturned
43 // very infrequently. We are willing to perform expensive recovery
44 // operations when they are overturned. The benefit, of course, is
45 // performing optimistic optimizations (!) on the object code.
46 //
47 // Changes in the class hierarchy due to dynamic linking or
48 // class evolution can violate dependencies. There is enough
49 // indexing between classes and nmethods to make dependency
50 // checking reasonably efficient.
52 class ciEnv;
53 class nmethod;
54 class OopRecorder;
55 class xmlStream;
56 class CompileLog;
57 class DepChange;
58 class KlassDepChange;
59 class CallSiteDepChange;
60 class No_Safepoint_Verifier;
62 class Dependencies: public ResourceObj {
63 public:
64 // Note: In the comments on dependency types, most uses of the terms
65 // subtype and supertype are used in a "non-strict" or "inclusive"
66 // sense, and are starred to remind the reader of this fact.
67 // Strict uses of the terms use the word "proper".
68 //
69 // Specifically, every class is its own subtype* and supertype*.
70 // (This trick is easier than continually saying things like "Y is a
71 // subtype of X or X itself".)
72 //
73 // Sometimes we write X > Y to mean X is a proper supertype of Y.
74 // The notation X > {Y, Z} means X has proper subtypes Y, Z.
75 // The notation X.m > Y means that Y inherits m from X, while
76 // X.m > Y.m means Y overrides X.m. A star denotes abstractness,
77 // as *I > A, meaning (abstract) interface I is a super type of A,
78 // or A.*m > B.m, meaning B.m implements abstract method A.m.
79 //
80 // In this module, the terms "subtype" and "supertype" refer to
81 // Java-level reference type conversions, as detected by
82 // "instanceof" and performed by "checkcast" operations. The method
83 // Klass::is_subtype_of tests these relations. Note that "subtype"
84 // is richer than "subclass" (as tested by Klass::is_subclass_of),
85 // since it takes account of relations involving interface and array
86 // types.
87 //
88 // To avoid needless complexity, dependencies involving array types
89 // are not accepted. If you need to make an assertion about an
90 // array type, make the assertion about its corresponding element
91 // types. Any assertion that might change about an array type can
92 // be converted to an assertion about its element type.
93 //
94 // Most dependencies are evaluated over a "context type" CX, which
95 // stands for the set Subtypes(CX) of every Java type that is a subtype*
96 // of CX. When the system loads a new class or interface N, it is
97 // responsible for re-evaluating changed dependencies whose context
98 // type now includes N, that is, all super types of N.
99 //
100 enum DepType {
101 end_marker = 0,
103 // An 'evol' dependency simply notes that the contents of the
104 // method were used. If it evolves (is replaced), the nmethod
105 // must be recompiled. No other dependencies are implied.
106 evol_method,
107 FIRST_TYPE = evol_method,
109 // A context type CX is a leaf it if has no proper subtype.
110 leaf_type,
112 // An abstract class CX has exactly one concrete subtype CC.
113 abstract_with_unique_concrete_subtype,
115 // The type CX is purely abstract, with no concrete subtype* at all.
116 abstract_with_no_concrete_subtype,
118 // The concrete CX is free of concrete proper subtypes.
119 concrete_with_no_concrete_subtype,
121 // Given a method M1 and a context class CX, the set MM(CX, M1) of
122 // "concrete matching methods" in CX of M1 is the set of every
123 // concrete M2 for which it is possible to create an invokevirtual
124 // or invokeinterface call site that can reach either M1 or M2.
125 // That is, M1 and M2 share a name, signature, and vtable index.
126 // We wish to notice when the set MM(CX, M1) is just {M1}, or
127 // perhaps a set of two {M1,M2}, and issue dependencies on this.
129 // The set MM(CX, M1) can be computed by starting with any matching
130 // concrete M2 that is inherited into CX, and then walking the
131 // subtypes* of CX looking for concrete definitions.
133 // The parameters to this dependency are the method M1 and the
134 // context class CX. M1 must be either inherited in CX or defined
135 // in a subtype* of CX. It asserts that MM(CX, M1) is no greater
136 // than {M1}.
137 unique_concrete_method, // one unique concrete method under CX
139 // An "exclusive" assertion concerns two methods or subtypes, and
140 // declares that there are at most two (or perhaps later N>2)
141 // specific items that jointly satisfy the restriction.
142 // We list all items explicitly rather than just giving their
143 // count, for robustness in the face of complex schema changes.
145 // A context class CX (which may be either abstract or concrete)
146 // has two exclusive concrete subtypes* C1, C2 if every concrete
147 // subtype* of CX is either C1 or C2. Note that if neither C1 or C2
148 // are equal to CX, then CX itself must be abstract. But it is
149 // also possible (for example) that C1 is CX (a concrete class)
150 // and C2 is a proper subtype of C1.
151 abstract_with_exclusive_concrete_subtypes_2,
153 // This dependency asserts that MM(CX, M1) is no greater than {M1,M2}.
154 exclusive_concrete_methods_2,
156 // This dependency asserts that no instances of class or it's
157 // subclasses require finalization registration.
158 no_finalizable_subclasses,
160 // This dependency asserts when the CallSite.target value changed.
161 call_site_target_value,
163 TYPE_LIMIT
164 };
165 enum {
166 LG2_TYPE_LIMIT = 4, // assert(TYPE_LIMIT <= (1<<LG2_TYPE_LIMIT))
168 // handy categorizations of dependency types:
169 all_types = ((1 << TYPE_LIMIT) - 1) & ((-1) << FIRST_TYPE),
171 non_klass_types = (1 << call_site_target_value),
172 klass_types = all_types & ~non_klass_types,
174 non_ctxk_types = (1 << evol_method),
175 implicit_ctxk_types = (1 << call_site_target_value),
176 explicit_ctxk_types = all_types & ~(non_ctxk_types | implicit_ctxk_types),
178 max_arg_count = 3, // current maximum number of arguments (incl. ctxk)
180 // A "context type" is a class or interface that
181 // provides context for evaluating a dependency.
182 // When present, it is one of the arguments (dep_context_arg).
183 //
184 // If a dependency does not have a context type, there is a
185 // default context, depending on the type of the dependency.
186 // This bit signals that a default context has been compressed away.
187 default_context_type_bit = (1<<LG2_TYPE_LIMIT)
188 };
190 static const char* dep_name(DepType dept);
191 static int dep_args(DepType dept);
193 static bool is_klass_type( DepType dept) { return dept_in_mask(dept, klass_types ); }
195 static bool has_explicit_context_arg(DepType dept) { return dept_in_mask(dept, explicit_ctxk_types); }
196 static bool has_implicit_context_arg(DepType dept) { return dept_in_mask(dept, implicit_ctxk_types); }
198 static int dep_context_arg(DepType dept) { return has_explicit_context_arg(dept) ? 0 : -1; }
199 static int dep_implicit_context_arg(DepType dept) { return has_implicit_context_arg(dept) ? 0 : -1; }
201 static void check_valid_dependency_type(DepType dept);
203 private:
204 // State for writing a new set of dependencies:
205 GrowableArray<int>* _dep_seen; // (seen[h->ident] & (1<<dept))
206 GrowableArray<ciObject*>* _deps[TYPE_LIMIT];
208 static const char* _dep_name[TYPE_LIMIT];
209 static int _dep_args[TYPE_LIMIT];
211 static bool dept_in_mask(DepType dept, int mask) {
212 return (int)dept >= 0 && dept < TYPE_LIMIT && ((1<<dept) & mask) != 0;
213 }
215 bool note_dep_seen(int dept, ciObject* x) {
216 assert(dept < BitsPerInt, "oob");
217 int x_id = x->ident();
218 assert(_dep_seen != NULL, "deps must be writable");
219 int seen = _dep_seen->at_grow(x_id, 0);
220 _dep_seen->at_put(x_id, seen | (1<<dept));
221 // return true if we've already seen dept/x
222 return (seen & (1<<dept)) != 0;
223 }
225 bool maybe_merge_ctxk(GrowableArray<ciObject*>* deps,
226 int ctxk_i, ciKlass* ctxk);
228 void sort_all_deps();
229 size_t estimate_size_in_bytes();
231 // Initialize _deps, etc.
232 void initialize(ciEnv* env);
234 // State for making a new set of dependencies:
235 OopRecorder* _oop_recorder;
237 // Logging support
238 CompileLog* _log;
240 address _content_bytes; // everything but the oop references, encoded
241 size_t _size_in_bytes;
243 public:
244 // Make a new empty dependencies set.
245 Dependencies(ciEnv* env) {
246 initialize(env);
247 }
249 private:
250 // Check for a valid context type.
251 // Enforce the restriction against array types.
252 static void check_ctxk(ciKlass* ctxk) {
253 assert(ctxk->is_instance_klass(), "java types only");
254 }
255 static void check_ctxk_concrete(ciKlass* ctxk) {
256 assert(is_concrete_klass(ctxk->as_instance_klass()), "must be concrete");
257 }
258 static void check_ctxk_abstract(ciKlass* ctxk) {
259 check_ctxk(ctxk);
260 assert(!is_concrete_klass(ctxk->as_instance_klass()), "must be abstract");
261 }
263 void assert_common_1(DepType dept, ciObject* x);
264 void assert_common_2(DepType dept, ciObject* x0, ciObject* x1);
265 void assert_common_3(DepType dept, ciKlass* ctxk, ciObject* x1, ciObject* x2);
267 public:
268 // Adding assertions to a new dependency set at compile time:
269 void assert_evol_method(ciMethod* m);
270 void assert_leaf_type(ciKlass* ctxk);
271 void assert_abstract_with_unique_concrete_subtype(ciKlass* ctxk, ciKlass* conck);
272 void assert_abstract_with_no_concrete_subtype(ciKlass* ctxk);
273 void assert_concrete_with_no_concrete_subtype(ciKlass* ctxk);
274 void assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm);
275 void assert_abstract_with_exclusive_concrete_subtypes(ciKlass* ctxk, ciKlass* k1, ciKlass* k2);
276 void assert_exclusive_concrete_methods(ciKlass* ctxk, ciMethod* m1, ciMethod* m2);
277 void assert_has_no_finalizable_subclasses(ciKlass* ctxk);
278 void assert_call_site_target_value(ciCallSite* call_site, ciMethodHandle* method_handle);
280 // Define whether a given method or type is concrete.
281 // These methods define the term "concrete" as used in this module.
282 // For this module, an "abstract" class is one which is non-concrete.
283 //
284 // Future optimizations may allow some classes to remain
285 // non-concrete until their first instantiation, and allow some
286 // methods to remain non-concrete until their first invocation.
287 // In that case, there would be a middle ground between concrete
288 // and abstract (as defined by the Java language and VM).
289 static bool is_concrete_klass(klassOop k); // k is instantiable
290 static bool is_concrete_method(methodOop m); // m is invocable
291 static Klass* find_finalizable_subclass(Klass* k);
293 // These versions of the concreteness queries work through the CI.
294 // The CI versions are allowed to skew sometimes from the VM
295 // (oop-based) versions. The cost of such a difference is a
296 // (safely) aborted compilation, or a deoptimization, or a missed
297 // optimization opportunity.
298 //
299 // In order to prevent spurious assertions, query results must
300 // remain stable within any single ciEnv instance. (I.e., they must
301 // not go back into the VM to get their value; they must cache the
302 // bit in the CI, either eagerly or lazily.)
303 static bool is_concrete_klass(ciInstanceKlass* k); // k appears instantiable
304 static bool is_concrete_method(ciMethod* m); // m appears invocable
305 static bool has_finalizable_subclass(ciInstanceKlass* k);
307 // As a general rule, it is OK to compile under the assumption that
308 // a given type or method is concrete, even if it at some future
309 // point becomes abstract. So dependency checking is one-sided, in
310 // that it permits supposedly concrete classes or methods to turn up
311 // as really abstract. (This shouldn't happen, except during class
312 // evolution, but that's the logic of the checking.) However, if a
313 // supposedly abstract class or method suddenly becomes concrete, a
314 // dependency on it must fail.
316 // Checking old assertions at run-time (in the VM only):
317 static klassOop check_evol_method(methodOop m);
318 static klassOop check_leaf_type(klassOop ctxk);
319 static klassOop check_abstract_with_unique_concrete_subtype(klassOop ctxk, klassOop conck,
320 KlassDepChange* changes = NULL);
321 static klassOop check_abstract_with_no_concrete_subtype(klassOop ctxk,
322 KlassDepChange* changes = NULL);
323 static klassOop check_concrete_with_no_concrete_subtype(klassOop ctxk,
324 KlassDepChange* changes = NULL);
325 static klassOop check_unique_concrete_method(klassOop ctxk, methodOop uniqm,
326 KlassDepChange* changes = NULL);
327 static klassOop check_abstract_with_exclusive_concrete_subtypes(klassOop ctxk, klassOop k1, klassOop k2,
328 KlassDepChange* changes = NULL);
329 static klassOop check_exclusive_concrete_methods(klassOop ctxk, methodOop m1, methodOop m2,
330 KlassDepChange* changes = NULL);
331 static klassOop check_has_no_finalizable_subclasses(klassOop ctxk, KlassDepChange* changes = NULL);
332 static klassOop check_call_site_target_value(oop call_site, oop method_handle, CallSiteDepChange* changes = NULL);
333 // A returned klassOop is NULL if the dependency assertion is still
334 // valid. A non-NULL klassOop is a 'witness' to the assertion
335 // failure, a point in the class hierarchy where the assertion has
336 // been proven false. For example, if check_leaf_type returns
337 // non-NULL, the value is a subtype of the supposed leaf type. This
338 // witness value may be useful for logging the dependency failure.
339 // Note that, when a dependency fails, there may be several possible
340 // witnesses to the failure. The value returned from the check_foo
341 // method is chosen arbitrarily.
343 // The 'changes' value, if non-null, requests a limited spot-check
344 // near the indicated recent changes in the class hierarchy.
345 // It is used by DepStream::spot_check_dependency_at.
347 // Detecting possible new assertions:
348 static klassOop find_unique_concrete_subtype(klassOop ctxk);
349 static methodOop find_unique_concrete_method(klassOop ctxk, methodOop m);
350 static int find_exclusive_concrete_subtypes(klassOop ctxk, int klen, klassOop k[]);
351 static int find_exclusive_concrete_methods(klassOop ctxk, int mlen, methodOop m[]);
353 // Create the encoding which will be stored in an nmethod.
354 void encode_content_bytes();
356 address content_bytes() {
357 assert(_content_bytes != NULL, "encode it first");
358 return _content_bytes;
359 }
360 size_t size_in_bytes() {
361 assert(_content_bytes != NULL, "encode it first");
362 return _size_in_bytes;
363 }
365 OopRecorder* oop_recorder() { return _oop_recorder; }
366 CompileLog* log() { return _log; }
368 void copy_to(nmethod* nm);
370 void log_all_dependencies();
371 void log_dependency(DepType dept, int nargs, ciObject* args[]) {
372 write_dependency_to(log(), dept, nargs, args);
373 }
374 void log_dependency(DepType dept,
375 ciObject* x0,
376 ciObject* x1 = NULL,
377 ciObject* x2 = NULL) {
378 if (log() == NULL) return;
379 ciObject* args[max_arg_count];
380 args[0] = x0;
381 args[1] = x1;
382 args[2] = x2;
383 assert(2 < max_arg_count, "");
384 log_dependency(dept, dep_args(dept), args);
385 }
387 static void write_dependency_to(CompileLog* log,
388 DepType dept,
389 int nargs, ciObject* args[],
390 klassOop witness = NULL);
391 static void write_dependency_to(CompileLog* log,
392 DepType dept,
393 int nargs, oop args[],
394 klassOop witness = NULL);
395 static void write_dependency_to(xmlStream* xtty,
396 DepType dept,
397 int nargs, oop args[],
398 klassOop witness = NULL);
399 static void print_dependency(DepType dept,
400 int nargs, oop args[],
401 klassOop witness = NULL);
403 private:
404 // helper for encoding common context types as zero:
405 static ciKlass* ctxk_encoded_as_null(DepType dept, ciObject* x);
407 static klassOop ctxk_encoded_as_null(DepType dept, oop x);
409 public:
410 // Use this to iterate over an nmethod's dependency set.
411 // Works on new and old dependency sets.
412 // Usage:
413 //
414 // ;
415 // Dependencies::DepType dept;
416 // for (Dependencies::DepStream deps(nm); deps.next(); ) {
417 // ...
418 // }
419 //
420 // The caller must be in the VM, since oops are not wrapped in handles.
421 class DepStream {
422 private:
423 nmethod* _code; // null if in a compiler thread
424 Dependencies* _deps; // null if not in a compiler thread
425 CompressedReadStream _bytes;
426 #ifdef ASSERT
427 size_t _byte_limit;
428 #endif
430 // iteration variables:
431 DepType _type;
432 int _xi[max_arg_count+1];
434 void initial_asserts(size_t byte_limit) NOT_DEBUG({});
436 inline oop recorded_oop_at(int i);
437 // => _code? _code->oop_at(i): *_deps->_oop_recorder->handle_at(i)
439 klassOop check_klass_dependency(KlassDepChange* changes);
440 klassOop check_call_site_dependency(CallSiteDepChange* changes);
442 void trace_and_log_witness(klassOop witness);
444 public:
445 DepStream(Dependencies* deps)
446 : _deps(deps),
447 _code(NULL),
448 _bytes(deps->content_bytes())
449 {
450 initial_asserts(deps->size_in_bytes());
451 }
452 DepStream(nmethod* code)
453 : _deps(NULL),
454 _code(code),
455 _bytes(code->dependencies_begin())
456 {
457 initial_asserts(code->dependencies_size());
458 }
460 bool next();
462 DepType type() { return _type; }
463 int argument_count() { return dep_args(type()); }
464 int argument_index(int i) { assert(0 <= i && i < argument_count(), "oob");
465 return _xi[i]; }
466 oop argument(int i); // => recorded_oop_at(argument_index(i))
467 klassOop context_type();
469 bool is_klass_type() { return Dependencies::is_klass_type(type()); }
471 methodOop method_argument(int i) {
472 oop x = argument(i);
473 assert(x->is_method(), "type");
474 return (methodOop) x;
475 }
476 klassOop type_argument(int i) {
477 oop x = argument(i);
478 assert(x->is_klass(), "type");
479 return (klassOop) x;
480 }
482 // The point of the whole exercise: Is this dep still OK?
483 klassOop check_dependency() {
484 klassOop result = check_klass_dependency(NULL);
485 if (result != NULL) return result;
486 return check_call_site_dependency(NULL);
487 }
489 // A lighter version: Checks only around recent changes in a class
490 // hierarchy. (See Universe::flush_dependents_on.)
491 klassOop spot_check_dependency_at(DepChange& changes);
493 // Log the current dependency to xtty or compilation log.
494 void log_dependency(klassOop witness = NULL);
496 // Print the current dependency to tty.
497 void print_dependency(klassOop witness = NULL, bool verbose = false);
498 };
499 friend class Dependencies::DepStream;
501 static void print_statistics() PRODUCT_RETURN;
502 };
505 // Every particular DepChange is a sub-class of this class.
506 class DepChange : public StackObj {
507 public:
508 // What kind of DepChange is this?
509 virtual bool is_klass_change() const { return false; }
510 virtual bool is_call_site_change() const { return false; }
512 // Subclass casting with assertions.
513 KlassDepChange* as_klass_change() {
514 assert(is_klass_change(), "bad cast");
515 return (KlassDepChange*) this;
516 }
517 CallSiteDepChange* as_call_site_change() {
518 assert(is_call_site_change(), "bad cast");
519 return (CallSiteDepChange*) this;
520 }
522 void print();
524 public:
525 enum ChangeType {
526 NO_CHANGE = 0, // an uninvolved klass
527 Change_new_type, // a newly loaded type
528 Change_new_sub, // a super with a new subtype
529 Change_new_impl, // an interface with a new implementation
530 CHANGE_LIMIT,
531 Start_Klass = CHANGE_LIMIT // internal indicator for ContextStream
532 };
534 // Usage:
535 // for (DepChange::ContextStream str(changes); str.next(); ) {
536 // klassOop k = str.klass();
537 // switch (str.change_type()) {
538 // ...
539 // }
540 // }
541 class ContextStream : public StackObj {
542 private:
543 DepChange& _changes;
544 friend class DepChange;
546 // iteration variables:
547 ChangeType _change_type;
548 klassOop _klass;
549 objArrayOop _ti_base; // i.e., transitive_interfaces
550 int _ti_index;
551 int _ti_limit;
553 // start at the beginning:
554 void start();
556 public:
557 ContextStream(DepChange& changes)
558 : _changes(changes)
559 { start(); }
561 ContextStream(DepChange& changes, No_Safepoint_Verifier& nsv)
562 : _changes(changes)
563 // the nsv argument makes it safe to hold oops like _klass
564 { start(); }
566 bool next();
568 ChangeType change_type() { return _change_type; }
569 klassOop klass() { return _klass; }
570 };
571 friend class DepChange::ContextStream;
572 };
575 // A class hierarchy change coming through the VM (under the Compile_lock).
576 // The change is structured as a single new type with any number of supers
577 // and implemented interface types. Other than the new type, any of the
578 // super types can be context types for a relevant dependency, which the
579 // new type could invalidate.
580 class KlassDepChange : public DepChange {
581 private:
582 // each change set is rooted in exactly one new type (at present):
583 KlassHandle _new_type;
585 void initialize();
587 public:
588 // notes the new type, marks it and all its super-types
589 KlassDepChange(KlassHandle new_type)
590 : _new_type(new_type)
591 {
592 initialize();
593 }
595 // cleans up the marks
596 ~KlassDepChange();
598 // What kind of DepChange is this?
599 virtual bool is_klass_change() const { return true; }
601 klassOop new_type() { return _new_type(); }
603 // involves_context(k) is true if k is new_type or any of the super types
604 bool involves_context(klassOop k);
605 };
608 // A CallSite has changed its target.
609 class CallSiteDepChange : public DepChange {
610 private:
611 Handle _call_site;
612 Handle _method_handle;
614 public:
615 CallSiteDepChange(Handle call_site, Handle method_handle)
616 : _call_site(call_site),
617 _method_handle(method_handle)
618 {
619 assert(_call_site() ->is_a(SystemDictionary::CallSite_klass()), "must be");
620 assert(_method_handle()->is_a(SystemDictionary::MethodHandle_klass()), "must be");
621 }
623 // What kind of DepChange is this?
624 virtual bool is_call_site_change() const { return true; }
626 oop call_site() const { return _call_site(); }
627 oop method_handle() const { return _method_handle(); }
628 };
630 #endif // SHARE_VM_CODE_DEPENDENCIES_HPP