1 /*
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24
25 #ifndef SHARE_PRIMS_JVMTIREDEFINECLASSES_HPP
26 #define SHARE_PRIMS_JVMTIREDEFINECLASSES_HPP
27
28 #include "jvmtifiles/jvmtiEnv.hpp"
29 #include "memory/oopFactory.hpp"
30 #include "memory/resourceArea.hpp"
31 #include "oops/objArrayKlass.hpp"
32 #include "oops/objArrayOop.hpp"
33 #include "runtime/vmOperations.hpp"
34
35 // Introduction:
36 //
37 // The RedefineClasses() API is used to change the definition of one or
38 // more classes. While the API supports redefining more than one class
39 // in a single call, in general, the API is discussed in the context of
40 // changing the definition of a single current class to a single new
41 // class. For clarity, the current class is will always be called
42 // "the_class" and the new class will always be called "scratch_class".
43 //
44 // The name "the_class" is used because there is only one structure
45 // that represents a specific class; redefinition does not replace the
46 // structure, but instead replaces parts of the structure. The name
47 // "scratch_class" is used because the structure that represents the
48 // new definition of a specific class is simply used to carry around
49 // the parts of the new definition until they are used to replace the
50 // appropriate parts in the_class. Once redefinition of a class is
51 // complete, scratch_class is thrown away.
52 //
53 //
54 // Implementation Overview:
55 //
56 // The RedefineClasses() API is mostly a wrapper around the VM op that
57 // does the real work. The work is split in varying degrees between
58 // doit_prologue(), doit() and doit_epilogue().
59 //
60 // 1) doit_prologue() is called by the JavaThread on the way to a
61 // safepoint. It does parameter verification and loads scratch_class
62 // which involves:
63 // - parsing the incoming class definition using the_class' class
64 // loader and security context
65 // - linking scratch_class
66 // - merging constant pools and rewriting bytecodes as needed
67 // for the merged constant pool
68 // - verifying the bytecodes in scratch_class
69 // - setting up the constant pool cache and rewriting bytecodes
70 // as needed to use the cache
71 // - finally, scratch_class is compared to the_class to verify
72 // that it is a valid replacement class
73 // - if everything is good, then scratch_class is saved in an
74 // instance field in the VM operation for the doit() call
75 //
76 // Note: A JavaThread must do the above work.
77 //
78 // 2) doit() is called by the VMThread during a safepoint. It installs
79 // the new class definition(s) which involves:
80 // - retrieving the scratch_class from the instance field in the
81 // VM operation
82 // - house keeping (flushing breakpoints and caches, deoptimizing
83 // dependent compiled code)
84 // - replacing parts in the_class with parts from scratch_class
85 // - adding weak reference(s) to track the obsolete but interesting
86 // parts of the_class
87 // - adjusting constant pool caches and vtables in other classes
88 // that refer to methods in the_class. These adjustments use the
89 // ClassLoaderDataGraph::classes_do() facility which only allows
90 // a helper method to be specified. The interesting parameters
91 // that we would like to pass to the helper method are saved in
92 // static global fields in the VM operation.
93 // - telling the SystemDictionary to notice our changes
94 //
95 // Note: the above work must be done by the VMThread to be safe.
96 //
97 // 3) doit_epilogue() is called by the JavaThread after the VM op
98 // is finished and the safepoint is done. It simply cleans up
99 // memory allocated in doit_prologue() and used in doit().
100 //
101 //
102 // Constant Pool Details:
103 //
104 // When the_class is redefined, we cannot just replace the constant
105 // pool in the_class with the constant pool from scratch_class because
106 // that could confuse obsolete methods that may still be running.
107 // Instead, the constant pool from the_class, old_cp, is merged with
108 // the constant pool from scratch_class, scratch_cp. The resulting
109 // constant pool, merge_cp, replaces old_cp in the_class.
110 //
111 // The key part of any merging algorithm is the entry comparison
112 // function so we have to know the types of entries in a constant pool
113 // in order to merge two of them together. Constant pools can contain
114 // up to 12 different kinds of entries; the JVM_CONSTANT_Unicode entry
115 // is not presently used so we only have to worry about the other 11
116 // entry types. For the purposes of constant pool merging, it is
117 // helpful to know that the 11 entry types fall into 3 different
118 // subtypes: "direct", "indirect" and "double-indirect".
119 //
120 // Direct CP entries contain data and do not contain references to
121 // other CP entries. The following are direct CP entries:
122 // JVM_CONSTANT_{Double,Float,Integer,Long,Utf8}
123 //
124 // Indirect CP entries contain 1 or 2 references to a direct CP entry
125 // and no other data. The following are indirect CP entries:
126 // JVM_CONSTANT_{Class,NameAndType,String}
127 //
128 // Double-indirect CP entries contain two references to indirect CP
129 // entries and no other data. The following are double-indirect CP
130 // entries:
131 // JVM_CONSTANT_{Fieldref,InterfaceMethodref,Methodref}
132 //
133 // When comparing entries between two constant pools, the entry types
134 // are compared first and if they match, then further comparisons are
135 // made depending on the entry subtype. Comparing direct CP entries is
136 // simply a matter of comparing the data associated with each entry.
137 // Comparing both indirect and double-indirect CP entries requires
138 // recursion.
139 //
140 // Fortunately, the recursive combinations are limited because indirect
141 // CP entries can only refer to direct CP entries and double-indirect
142 // CP entries can only refer to indirect CP entries. The following is
143 // an example illustration of the deepest set of indirections needed to
144 // access the data associated with a JVM_CONSTANT_Fieldref entry:
145 //
146 // JVM_CONSTANT_Fieldref {
147 // class_index => JVM_CONSTANT_Class {
148 // name_index => JVM_CONSTANT_Utf8 {
149 // <data-1>
150 // }
151 // }
152 // name_and_type_index => JVM_CONSTANT_NameAndType {
153 // name_index => JVM_CONSTANT_Utf8 {
154 // <data-2>
155 // }
156 // descriptor_index => JVM_CONSTANT_Utf8 {
157 // <data-3>
158 // }
159 // }
160 // }
161 //
162 // The above illustration is not a data structure definition for any
163 // computer language. The curly braces ('{' and '}') are meant to
164 // delimit the context of the "fields" in the CP entry types shown.
165 // Each indirection from the JVM_CONSTANT_Fieldref entry is shown via
166 // "=>", e.g., the class_index is used to indirectly reference a
167 // JVM_CONSTANT_Class entry where the name_index is used to indirectly
168 // reference a JVM_CONSTANT_Utf8 entry which contains the interesting
169 // <data-1>. In order to understand a JVM_CONSTANT_Fieldref entry, we
170 // have to do a total of 5 indirections just to get to the CP entries
171 // that contain the interesting pieces of data and then we have to
172 // fetch the three pieces of data. This means we have to do a total of
173 // (5 + 3) * 2 == 16 dereferences to compare two JVM_CONSTANT_Fieldref
174 // entries.
175 //
176 // Here is the indirection, data and dereference count for each entry
177 // type:
178 //
179 // JVM_CONSTANT_Class 1 indir, 1 data, 2 derefs
180 // JVM_CONSTANT_Double 0 indir, 1 data, 1 deref
181 // JVM_CONSTANT_Fieldref 2 indir, 3 data, 8 derefs
182 // JVM_CONSTANT_Float 0 indir, 1 data, 1 deref
183 // JVM_CONSTANT_Integer 0 indir, 1 data, 1 deref
184 // JVM_CONSTANT_InterfaceMethodref 2 indir, 3 data, 8 derefs
185 // JVM_CONSTANT_Long 0 indir, 1 data, 1 deref
186 // JVM_CONSTANT_Methodref 2 indir, 3 data, 8 derefs
187 // JVM_CONSTANT_NameAndType 1 indir, 2 data, 4 derefs
188 // JVM_CONSTANT_String 1 indir, 1 data, 2 derefs
189 // JVM_CONSTANT_Utf8 0 indir, 1 data, 1 deref
190 //
191 // So different subtypes of CP entries require different amounts of
192 // work for a proper comparison.
193 //
194 // Now that we've talked about the different entry types and how to
195 // compare them we need to get back to merging. This is not a merge in
196 // the "sort -u" sense or even in the "sort" sense. When we merge two
197 // constant pools, we copy all the entries from old_cp to merge_cp,
198 // preserving entry order. Next we append all the unique entries from
199 // scratch_cp to merge_cp and we track the index changes from the
200 // location in scratch_cp to the possibly new location in merge_cp.
201 // When we are done, any obsolete code that is still running that
202 // uses old_cp should not be able to observe any difference if it
203 // were to use merge_cp. As for the new code in scratch_class, it is
204 // modified to use the appropriate index values in merge_cp before it
205 // is used to replace the code in the_class.
206 //
207 // There is one small complication in copying the entries from old_cp
208 // to merge_cp. Two of the CP entry types are special in that they are
209 // lazily resolved. Before explaining the copying complication, we need
210 // to digress into CP entry resolution.
211 //
212 // JVM_CONSTANT_Class entries are present in the class file, but are not
213 // stored in memory as such until they are resolved. The entries are not
214 // resolved unless they are used because resolution is expensive. During class
215 // file parsing the entries are initially stored in memory as
216 // JVM_CONSTANT_ClassIndex and JVM_CONSTANT_StringIndex entries. These special
217 // CP entry types indicate that the JVM_CONSTANT_Class and JVM_CONSTANT_String
218 // entries have been parsed, but the index values in the entries have not been
219 // validated. After the entire constant pool has been parsed, the index
220 // values can be validated and then the entries are converted into
221 // JVM_CONSTANT_UnresolvedClass and JVM_CONSTANT_String
222 // entries. During this conversion process, the UTF8 values that are
223 // indirectly referenced by the JVM_CONSTANT_ClassIndex and
224 // JVM_CONSTANT_StringIndex entries are changed into Symbol*s and the
225 // entries are modified to refer to the Symbol*s. This optimization
226 // eliminates one level of indirection for those two CP entry types and
227 // gets the entries ready for verification. Verification expects to
228 // find JVM_CONSTANT_UnresolvedClass but not JVM_CONSTANT_Class entries.
229 //
230 // Now we can get back to the copying complication. When we copy
231 // entries from old_cp to merge_cp, we have to revert any
232 // JVM_CONSTANT_Class entries to JVM_CONSTANT_UnresolvedClass entries
233 // or verification will fail.
234 //
235 // It is important to explicitly state that the merging algorithm
236 // effectively unresolves JVM_CONSTANT_Class entries that were in the
237 // old_cp when they are changed into JVM_CONSTANT_UnresolvedClass
238 // entries in the merge_cp. This is done both to make verification
239 // happy and to avoid adding more brittleness between RedefineClasses
240 // and the constant pool cache. By allowing the constant pool cache
241 // implementation to (re)resolve JVM_CONSTANT_UnresolvedClass entries
242 // into JVM_CONSTANT_Class entries, we avoid having to embed knowledge
243 // about those algorithms in RedefineClasses.
244 //
245 // Appending unique entries from scratch_cp to merge_cp is straight
246 // forward for direct CP entries and most indirect CP entries. For the
247 // indirect CP entry type JVM_CONSTANT_NameAndType and for the double-
248 // indirect CP entry types, the presence of more than one piece of
249 // interesting data makes appending the entries more complicated.
250 //
251 // For the JVM_CONSTANT_{Double,Float,Integer,Long,Utf8} entry types,
252 // the entry is simply copied from scratch_cp to the end of merge_cp.
253 // If the index in scratch_cp is different than the destination index
254 // in merge_cp, then the change in index value is tracked.
255 //
256 // Note: the above discussion for the direct CP entries also applies
257 // to the JVM_CONSTANT_UnresolvedClass entry types.
258 //
259 // For the JVM_CONSTANT_Class entry types, since there is only
260 // one data element at the end of the recursion, we know that we have
261 // either one or two unique entries. If the JVM_CONSTANT_Utf8 entry is
262 // unique then it is appended to merge_cp before the current entry.
263 // If the JVM_CONSTANT_Utf8 entry is not unique, then the current entry
264 // is updated to refer to the duplicate entry in merge_cp before it is
265 // appended to merge_cp. Again, any changes in index values are tracked
266 // as needed.
267 //
268 // Note: the above discussion for JVM_CONSTANT_Class entry
269 // types is theoretical. Since those entry types have already been
270 // optimized into JVM_CONSTANT_UnresolvedClass entry types,
271 // they are handled as direct CP entries.
272 //
273 // For the JVM_CONSTANT_NameAndType entry type, since there are two
274 // data elements at the end of the recursions, we know that we have
275 // between one and three unique entries. Any unique JVM_CONSTANT_Utf8
276 // entries are appended to merge_cp before the current entry. For any
277 // JVM_CONSTANT_Utf8 entries that are not unique, the current entry is
278 // updated to refer to the duplicate entry in merge_cp before it is
279 // appended to merge_cp. Again, any changes in index values are tracked
280 // as needed.
281 //
282 // For the JVM_CONSTANT_{Fieldref,InterfaceMethodref,Methodref} entry
283 // types, since there are two indirect CP entries and three data
284 // elements at the end of the recursions, we know that we have between
285 // one and six unique entries. See the JVM_CONSTANT_Fieldref diagram
286 // above for an example of all six entries. The uniqueness algorithm
287 // for the JVM_CONSTANT_Class and JVM_CONSTANT_NameAndType entries is
288 // covered above. Any unique entries are appended to merge_cp before
289 // the current entry. For any entries that are not unique, the current
290 // entry is updated to refer to the duplicate entry in merge_cp before
291 // it is appended to merge_cp. Again, any changes in index values are
292 // tracked as needed.
293 //
294 //
295 // Other Details:
296 //
297 // Details for other parts of RedefineClasses need to be written.
298 // This is a placeholder section.
299 //
300 //
301 // Open Issues (in no particular order):
302 //
303 // - How do we serialize the RedefineClasses() API without deadlocking?
304 //
305 // - SystemDictionary::parse_stream() was called with a NULL protection
306 // domain since the initial version. This has been changed to pass
307 // the_class->protection_domain(). This change has been tested with
308 // all NSK tests and nothing broke, but what will adding it now break
309 // in ways that we don't test?
310 //
311 // - GenerateOopMap::rewrite_load_or_store() has a comment in its
312 // (indirect) use of the Relocator class that the max instruction
313 // size is 4 bytes. goto_w and jsr_w are 5 bytes and wide/iinc is
314 // 6 bytes. Perhaps Relocator only needs a 4 byte buffer to do
315 // what it does to the bytecodes. More investigation is needed.
316 //
317 // - How do we know if redefine_single_class() and the guts of
318 // InstanceKlass are out of sync? I don't think this can be
319 // automated, but we should probably order the work in
320 // redefine_single_class() to match the order of field
321 // definitions in InstanceKlass. We also need to add some
322 // comments about keeping things in sync.
323 //
324 // - set_new_constant_pool() is huge and we should consider refactoring
325 // it into smaller chunks of work.
326 //
327 // - The exception table update code in set_new_constant_pool() defines
328 // const values that are also defined in a local context elsewhere.
329 // The same literal values are also used in elsewhere. We need to
330 // coordinate a cleanup of these constants with Runtime.
331 //
332
333 struct JvmtiCachedClassFileData {
334 jint length;
335 unsigned char data[1];
336 };
337
338 class VM_RedefineClasses: public VM_Operation {
339 private:
340 // These static fields are needed by ClassLoaderDataGraph::classes_do()
341 // facility and the CheckClass and AdjustAndCleanMetadata helpers.
342 static Array<Method*>* _old_methods;
343 static Array<Method*>* _new_methods;
344 static Method** _matching_old_methods;
345 static Method** _matching_new_methods;
346 static Method** _deleted_methods;
347 static Method** _added_methods;
348 static int _matching_methods_length;
349 static int _deleted_methods_length;
350 static int _added_methods_length;
351 static bool _has_redefined_Object;
352 static bool _has_null_class_loader;
353
354 // The instance fields are used to pass information from
355 // doit_prologue() to doit() and doit_epilogue().
356 Klass* _the_class;
357 jint _class_count;
358 const jvmtiClassDefinition *_class_defs; // ptr to _class_count defs
359
360 // This operation is used by both RedefineClasses and
361 // RetransformClasses. Indicate which.
362 JvmtiClassLoadKind _class_load_kind;
363
364 // _index_map_count is just an optimization for knowing if
365 // _index_map_p contains any entries.
366 int _index_map_count;
367 intArray * _index_map_p;
368
369 // _operands_index_map_count is just an optimization for knowing if
370 // _operands_index_map_p contains any entries.
371 int _operands_cur_length;
372 int _operands_index_map_count;
373 intArray * _operands_index_map_p;
374
375 // ptr to _class_count scratch_classes
376 InstanceKlass** _scratch_classes;
377 jvmtiError _res;
378
379 // Set if any of the InstanceKlasses have entries in the ResolvedMethodTable
380 // to avoid walking after redefinition if the redefined classes do not
381 // have any entries.
382 bool _any_class_has_resolved_methods;
383
384 // Performance measurement support. These timers do not cover all
385 // the work done for JVM/TI RedefineClasses() but they do cover
386 // the heavy lifting.
387 elapsedTimer _timer_rsc_phase1;
388 elapsedTimer _timer_rsc_phase2;
389 elapsedTimer _timer_vm_op_prologue;
390
391 // These routines are roughly in call order unless otherwise noted.
392
393 // Load the caller's new class definition(s) into _scratch_classes.
394 // Constant pool merging work is done here as needed. Also calls
395 // compare_and_normalize_class_versions() to verify the class
396 // definition(s).
397 jvmtiError load_new_class_versions(TRAPS);
398
399 // Verify that the caller provided class definition(s) that meet
400 // the restrictions of RedefineClasses. Normalize the order of
401 // overloaded methods as needed.
402 jvmtiError compare_and_normalize_class_versions(
403 InstanceKlass* the_class, InstanceKlass* scratch_class);
404
405 // Figure out which new methods match old methods in name and signature,
406 // which methods have been added, and which are no longer present
407 void compute_added_deleted_matching_methods();
408
409 // Change jmethodIDs to point to the new methods
410 void update_jmethod_ids(Thread* thread);
411
412 // In addition to marking methods as old and/or obsolete, this routine
413 // counts the number of methods that are EMCP (Equivalent Module Constant Pool).
414 int check_methods_and_mark_as_obsolete();
415 void transfer_old_native_function_registrations(InstanceKlass* the_class);
416
417 // Install the redefinition of a class
418 void redefine_single_class(jclass the_jclass,
419 InstanceKlass* scratch_class_oop, TRAPS);
420
421 void swap_annotations(InstanceKlass* new_class,
422 InstanceKlass* scratch_class);
423
424 // Increment the classRedefinedCount field in the specific InstanceKlass
425 // and in all direct and indirect subclasses.
426 void increment_class_counter(InstanceKlass *ik, TRAPS);
427
428 // Support for constant pool merging (these routines are in alpha order):
429 void append_entry(const constantPoolHandle& scratch_cp, int scratch_i,
430 constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS);
431 void append_operand(const constantPoolHandle& scratch_cp, int scratch_bootstrap_spec_index,
432 constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS);
433 void finalize_operands_merge(const constantPoolHandle& merge_cp, TRAPS);
434 int find_or_append_indirect_entry(const constantPoolHandle& scratch_cp, int scratch_i,
435 constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS);
436 int find_or_append_operand(const constantPoolHandle& scratch_cp, int scratch_bootstrap_spec_index,
437 constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS);
438 int find_new_index(int old_index);
439 int find_new_operand_index(int old_bootstrap_spec_index);
440 bool is_unresolved_class_mismatch(const constantPoolHandle& cp1, int index1,
441 const constantPoolHandle& cp2, int index2);
442 void map_index(const constantPoolHandle& scratch_cp, int old_index, int new_index);
443 void map_operand_index(int old_bootstrap_spec_index, int new_bootstrap_spec_index);
444 bool merge_constant_pools(const constantPoolHandle& old_cp,
445 const constantPoolHandle& scratch_cp, constantPoolHandle *merge_cp_p,
446 int *merge_cp_length_p, TRAPS);
447 jvmtiError merge_cp_and_rewrite(InstanceKlass* the_class,
448 InstanceKlass* scratch_class, TRAPS);
449 u2 rewrite_cp_ref_in_annotation_data(
450 AnnotationArray* annotations_typeArray, int &byte_i_ref,
451 const char * trace_mesg, TRAPS);
452 bool rewrite_cp_refs(InstanceKlass* scratch_class, TRAPS);
453 bool rewrite_cp_refs_in_annotation_struct(
454 AnnotationArray* class_annotations, int &byte_i_ref, TRAPS);
455 bool rewrite_cp_refs_in_annotations_typeArray(
456 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS);
457 bool rewrite_cp_refs_in_class_annotations(
458 InstanceKlass* scratch_class, TRAPS);
459 bool rewrite_cp_refs_in_element_value(
460 AnnotationArray* class_annotations, int &byte_i_ref, TRAPS);
461 bool rewrite_cp_refs_in_type_annotations_typeArray(
462 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
463 const char * location_mesg, TRAPS);
464 bool rewrite_cp_refs_in_type_annotation_struct(
465 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
466 const char * location_mesg, TRAPS);
467 bool skip_type_annotation_target(
468 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
469 const char * location_mesg, TRAPS);
470 bool skip_type_annotation_type_path(
471 AnnotationArray* type_annotations_typeArray, int &byte_i_ref, TRAPS);
472 bool rewrite_cp_refs_in_fields_annotations(
473 InstanceKlass* scratch_class, TRAPS);
474 bool rewrite_cp_refs_in_nest_attributes(InstanceKlass* scratch_class);
475 void rewrite_cp_refs_in_method(methodHandle method,
476 methodHandle * new_method_p, TRAPS);
477 bool rewrite_cp_refs_in_methods(InstanceKlass* scratch_class, TRAPS);
478 bool rewrite_cp_refs_in_methods_annotations(
479 InstanceKlass* scratch_class, TRAPS);
480 bool rewrite_cp_refs_in_methods_default_annotations(
481 InstanceKlass* scratch_class, TRAPS);
482 bool rewrite_cp_refs_in_methods_parameter_annotations(
483 InstanceKlass* scratch_class, TRAPS);
484 bool rewrite_cp_refs_in_class_type_annotations(
485 InstanceKlass* scratch_class, TRAPS);
486 bool rewrite_cp_refs_in_fields_type_annotations(
487 InstanceKlass* scratch_class, TRAPS);
488 bool rewrite_cp_refs_in_methods_type_annotations(
489 InstanceKlass* scratch_class, TRAPS);
490 void rewrite_cp_refs_in_stack_map_table(const methodHandle& method, TRAPS);
491 void rewrite_cp_refs_in_verification_type_info(
492 address& stackmap_addr_ref, address stackmap_end, u2 frame_i,
493 u1 frame_size, TRAPS);
494 void set_new_constant_pool(ClassLoaderData* loader_data,
495 InstanceKlass* scratch_class,
496 constantPoolHandle scratch_cp, int scratch_cp_length, TRAPS);
497
498 void flush_dependent_code();
499 void mark_dependent_code(InstanceKlass* ik);
500
501 // lock classes to redefine since constant pool merging isn't thread safe.
502 void lock_classes();
503 void unlock_classes();
504
505 static void dump_methods();
506
507 // Check that there are no old or obsolete methods
508 class CheckClass : public KlassClosure {
509 Thread* _thread;
510 public:
511 CheckClass(Thread* t) : _thread(t) {}
512 void do_klass(Klass* k);
513 };
514
515 // Unevolving classes may point to methods of the_class directly
516 // from their constant pool caches, itables, and/or vtables. We
517 // use the ClassLoaderDataGraph::classes_do() facility and this helper
518 // to fix up these pointers and clean MethodData out.
519 class AdjustAndCleanMetadata : public KlassClosure {
520 Thread* _thread;
521 public:
522 AdjustAndCleanMetadata(Thread* t) : _thread(t) {}
523 void do_klass(Klass* k);
524 };
525
526 public:
527 VM_RedefineClasses(jint class_count,
528 const jvmtiClassDefinition *class_defs,
529 JvmtiClassLoadKind class_load_kind);
530 VMOp_Type type() const { return VMOp_RedefineClasses; }
531 bool doit_prologue();
532 void doit();
533 void doit_epilogue();
534
535 bool allow_nested_vm_operations() const { return true; }
536 jvmtiError check_error() { return _res; }
537
538 // Modifiable test must be shared between IsModifiableClass query
539 // and redefine implementation
540 static bool is_modifiable_class(oop klass_mirror);
541
542 static jint get_cached_class_file_len(JvmtiCachedClassFileData *cache) {
543 return cache == NULL ? 0 : cache->length;
544 }
545 static unsigned char * get_cached_class_file_bytes(JvmtiCachedClassFileData *cache) {
546 return cache == NULL ? NULL : cache->data;
547 }
548
549 // Error printing
550 void print_on_error(outputStream* st) const;
551 };
552 #endif // SHARE_PRIMS_JVMTIREDEFINECLASSES_HPP