1 /*
2 * Copyright (c) 1997, 2019, 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.
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23 */
24
25 #ifndef SHARE_CODE_NMETHOD_HPP
26 #define SHARE_CODE_NMETHOD_HPP
27
28 #include "code/compiledMethod.hpp"
29
30 class DepChange;
31 class DirectiveSet;
32 class DebugInformationRecorder;
33
34 // nmethods (native methods) are the compiled code versions of Java methods.
35 //
36 // An nmethod contains:
37 // - header (the nmethod structure)
38 // [Relocation]
39 // - relocation information
40 // - constant part (doubles, longs and floats used in nmethod)
41 // - oop table
42 // [Code]
43 // - code body
44 // - exception handler
45 // - stub code
46 // [Debugging information]
47 // - oop array
48 // - data array
49 // - pcs
50 // [Exception handler table]
51 // - handler entry point array
52 // [Implicit Null Pointer exception table]
53 // - implicit null table array
54 // [Speculations]
55 // - encoded speculations array
56 // [JVMCINMethodData]
57 // - meta data for JVMCI compiled nmethod
58
59 #if INCLUDE_JVMCI
60 class FailedSpeculation;
61 class JVMCINMethodData;
62 #endif
63
64 class nmethod : public CompiledMethod {
65 friend class VMStructs;
66 friend class JVMCIVMStructs;
67 friend class NMethodSweeper;
68 friend class CodeCache; // scavengable oops
69 friend class JVMCINMethodData;
70 private:
71
72 // Shared fields for all nmethod's
73 int _entry_bci; // != InvocationEntryBci if this nmethod is an on-stack replacement method
74 jmethodID _jmethod_id; // Cache of method()->jmethod_id()
75
76 // To support simple linked-list chaining of nmethods:
77 nmethod* _osr_link; // from InstanceKlass::osr_nmethods_head
78
79 static nmethod* volatile _oops_do_mark_nmethods;
80 nmethod* volatile _oops_do_mark_link;
81
82 // offsets for entry points
83 address _entry_point; // entry point with class check
84 address _verified_entry_point; // entry point without class check
85 address _osr_entry_point; // entry point for on stack replacement
86
87 // Offsets for different nmethod parts
88 int _exception_offset;
89 // Offset of the unwind handler if it exists
90 int _unwind_handler_offset;
91
92 int _consts_offset;
93 int _stub_offset;
94 int _oops_offset; // offset to where embedded oop table begins (inside data)
95 int _metadata_offset; // embedded meta data table
96 int _scopes_data_offset;
97 int _scopes_pcs_offset;
98 int _dependencies_offset;
99 int _handler_table_offset;
100 int _nul_chk_table_offset;
101 #if INCLUDE_JVMCI
102 int _speculations_offset;
103 int _jvmci_data_offset;
104 #endif
105 int _nmethod_end_offset;
106
107 int code_offset() const { return (address) code_begin() - header_begin(); }
108
109 // location in frame (offset for sp) that deopt can store the original
110 // pc during a deopt.
111 int _orig_pc_offset;
112
113 int _compile_id; // which compilation made this nmethod
114 int _comp_level; // compilation level
115
116 // protected by CodeCache_lock
117 bool _has_flushed_dependencies; // Used for maintenance of dependencies (CodeCache_lock)
118
119 // used by jvmti to track if an unload event has been posted for this nmethod.
120 bool _unload_reported;
121
122 // Protected by Patching_lock
123 volatile signed char _state; // {not_installed, in_use, not_entrant, zombie, unloaded}
124
125 #ifdef ASSERT
126 bool _oops_are_stale; // indicates that it's no longer safe to access oops section
127 #endif
128
129 #if INCLUDE_RTM_OPT
130 // RTM state at compile time. Used during deoptimization to decide
131 // whether to restart collecting RTM locking abort statistic again.
132 RTMState _rtm_state;
133 #endif
134
135 // Nmethod Flushing lock. If non-zero, then the nmethod is not removed
136 // and is not made into a zombie. However, once the nmethod is made into
137 // a zombie, it will be locked one final time if CompiledMethodUnload
138 // event processing needs to be done.
139 volatile jint _lock_count;
140
141 // not_entrant method removal. Each mark_sweep pass will update
142 // this mark to current sweep invocation count if it is seen on the
143 // stack. An not_entrant method can be removed when there are no
144 // more activations, i.e., when the _stack_traversal_mark is less than
145 // current sweep traversal index.
146 volatile long _stack_traversal_mark;
147
148 // The _hotness_counter indicates the hotness of a method. The higher
149 // the value the hotter the method. The hotness counter of a nmethod is
150 // set to [(ReservedCodeCacheSize / (1024 * 1024)) * 2] each time the method
151 // is active while stack scanning (mark_active_nmethods()). The hotness
152 // counter is decreased (by 1) while sweeping.
153 int _hotness_counter;
154
155 // Local state used to keep track of whether unloading is happening or not
156 volatile uint8_t _is_unloading_state;
157
158 // These are used for compiled synchronized native methods to
159 // locate the owner and stack slot for the BasicLock so that we can
160 // properly revoke the bias of the owner if necessary. They are
161 // needed because there is no debug information for compiled native
162 // wrappers and the oop maps are insufficient to allow
163 // frame::retrieve_receiver() to work. Currently they are expected
164 // to be byte offsets from the Java stack pointer for maximum code
165 // sharing between platforms. Note that currently biased locking
166 // will never cause Class instances to be biased but this code
167 // handles the static synchronized case as well.
168 // JVMTI's GetLocalInstance() also uses these offsets to find the receiver
169 // for non-static native wrapper frames.
170 ByteSize _native_receiver_sp_offset;
171 ByteSize _native_basic_lock_sp_offset;
172
173 friend class nmethodLocker;
174
175 // For native wrappers
176 nmethod(Method* method,
177 CompilerType type,
178 int nmethod_size,
179 int compile_id,
180 CodeOffsets* offsets,
181 CodeBuffer *code_buffer,
182 int frame_size,
183 ByteSize basic_lock_owner_sp_offset, /* synchronized natives only */
184 ByteSize basic_lock_sp_offset, /* synchronized natives only */
185 OopMapSet* oop_maps);
186
187 // Creation support
188 nmethod(Method* method,
189 CompilerType type,
190 int nmethod_size,
191 int compile_id,
192 int entry_bci,
193 CodeOffsets* offsets,
194 int orig_pc_offset,
195 DebugInformationRecorder *recorder,
196 Dependencies* dependencies,
197 CodeBuffer *code_buffer,
198 int frame_size,
199 OopMapSet* oop_maps,
200 ExceptionHandlerTable* handler_table,
201 ImplicitExceptionTable* nul_chk_table,
202 AbstractCompiler* compiler,
203 int comp_level
204 #if INCLUDE_JVMCI
205 , char* speculations,
206 int speculations_len,
207 int jvmci_data_size
208 #endif
209 );
210
211 // helper methods
212 void* operator new(size_t size, int nmethod_size, int comp_level) throw();
213
214 const char* reloc_string_for(u_char* begin, u_char* end);
215 // Returns true if this thread changed the state of the nmethod or
216 // false if another thread performed the transition.
217 bool make_not_entrant_or_zombie(int state);
218 bool make_entrant() { Unimplemented(); return false; }
219 void inc_decompile_count();
220
221 // Inform external interfaces that a compiled method has been unloaded
222 void post_compiled_method_unload();
223
224 // Initailize fields to their default values
225 void init_defaults();
226
227 // Offsets
228 int content_offset() const { return content_begin() - header_begin(); }
229 int data_offset() const { return _data_offset; }
230
231 address header_end() const { return (address) header_begin() + header_size(); }
232
233 public:
234 // create nmethod with entry_bci
235 static nmethod* new_nmethod(const methodHandle& method,
236 int compile_id,
237 int entry_bci,
238 CodeOffsets* offsets,
239 int orig_pc_offset,
240 DebugInformationRecorder* recorder,
241 Dependencies* dependencies,
242 CodeBuffer *code_buffer,
243 int frame_size,
244 OopMapSet* oop_maps,
245 ExceptionHandlerTable* handler_table,
246 ImplicitExceptionTable* nul_chk_table,
247 AbstractCompiler* compiler,
248 int comp_level
249 #if INCLUDE_JVMCI
250 , char* speculations = NULL,
251 int speculations_len = 0,
252 int nmethod_mirror_index = -1,
253 const char* nmethod_mirror_name = NULL,
254 FailedSpeculation** failed_speculations = NULL
255 #endif
256 );
257
258 // Only used for unit tests.
259 nmethod()
260 : CompiledMethod(),
261 _is_unloading_state(0),
262 _native_receiver_sp_offset(in_ByteSize(-1)),
263 _native_basic_lock_sp_offset(in_ByteSize(-1)) {}
264
265
266 static nmethod* new_native_nmethod(const methodHandle& method,
267 int compile_id,
268 CodeBuffer *code_buffer,
269 int vep_offset,
270 int frame_complete,
271 int frame_size,
272 ByteSize receiver_sp_offset,
273 ByteSize basic_lock_sp_offset,
274 OopMapSet* oop_maps);
275
276 // type info
277 bool is_nmethod() const { return true; }
278 bool is_osr_method() const { return _entry_bci != InvocationEntryBci; }
279
280 // boundaries for different parts
281 address consts_begin () const { return header_begin() + _consts_offset ; }
282 address consts_end () const { return code_begin() ; }
283 address stub_begin () const { return header_begin() + _stub_offset ; }
284 address stub_end () const { return header_begin() + _oops_offset ; }
285 address exception_begin () const { return header_begin() + _exception_offset ; }
286 address unwind_handler_begin () const { return _unwind_handler_offset != -1 ? (header_begin() + _unwind_handler_offset) : NULL; }
287 oop* oops_begin () const { return (oop*) (header_begin() + _oops_offset) ; }
288 oop* oops_end () const { return (oop*) (header_begin() + _metadata_offset) ; }
289
290 Metadata** metadata_begin () const { return (Metadata**) (header_begin() + _metadata_offset) ; }
291 Metadata** metadata_end () const { return (Metadata**) _scopes_data_begin; }
292
293 address scopes_data_end () const { return header_begin() + _scopes_pcs_offset ; }
294 PcDesc* scopes_pcs_begin () const { return (PcDesc*)(header_begin() + _scopes_pcs_offset ); }
295 PcDesc* scopes_pcs_end () const { return (PcDesc*)(header_begin() + _dependencies_offset) ; }
296 address dependencies_begin () const { return header_begin() + _dependencies_offset ; }
297 address dependencies_end () const { return header_begin() + _handler_table_offset ; }
298 address handler_table_begin () const { return header_begin() + _handler_table_offset ; }
299 address handler_table_end () const { return header_begin() + _nul_chk_table_offset ; }
300 address nul_chk_table_begin () const { return header_begin() + _nul_chk_table_offset ; }
301 #if INCLUDE_JVMCI
302 address nul_chk_table_end () const { return header_begin() + _speculations_offset ; }
303 address speculations_begin () const { return header_begin() + _speculations_offset ; }
304 address speculations_end () const { return header_begin() + _jvmci_data_offset ; }
305 address jvmci_data_begin () const { return header_begin() + _jvmci_data_offset ; }
306 address jvmci_data_end () const { return header_begin() + _nmethod_end_offset ; }
307 #else
308 address nul_chk_table_end () const { return header_begin() + _nmethod_end_offset ; }
309 #endif
310
311 // Sizes
312 int oops_size () const { return (address) oops_end () - (address) oops_begin (); }
313 int metadata_size () const { return (address) metadata_end () - (address) metadata_begin (); }
314 int dependencies_size () const { return dependencies_end () - dependencies_begin (); }
315 #if INCLUDE_JVMCI
316 int speculations_size () const { return speculations_end () - speculations_begin (); }
317 int jvmci_data_size () const { return jvmci_data_end () - jvmci_data_begin (); }
318 #endif
319
320 int oops_count() const { assert(oops_size() % oopSize == 0, ""); return (oops_size() / oopSize) + 1; }
321 int metadata_count() const { assert(metadata_size() % wordSize == 0, ""); return (metadata_size() / wordSize) + 1; }
322
323 int total_size () const;
324
325 void dec_hotness_counter() { _hotness_counter--; }
326 void set_hotness_counter(int val) { _hotness_counter = val; }
327 int hotness_counter() const { return _hotness_counter; }
328
329 // Containment
330 bool oops_contains (oop* addr) const { return oops_begin () <= addr && addr < oops_end (); }
331 bool metadata_contains (Metadata** addr) const { return metadata_begin () <= addr && addr < metadata_end (); }
332 bool scopes_data_contains (address addr) const { return scopes_data_begin () <= addr && addr < scopes_data_end (); }
333 bool scopes_pcs_contains (PcDesc* addr) const { return scopes_pcs_begin () <= addr && addr < scopes_pcs_end (); }
334
335 // entry points
336 address entry_point() const { return _entry_point; } // normal entry point
337 address verified_entry_point() const { return _verified_entry_point; } // if klass is correct
338
339 // flag accessing and manipulation
340 bool is_not_installed() const { return _state == not_installed; }
341 bool is_in_use() const { return _state <= in_use; }
342 bool is_alive() const { return _state < zombie; }
343 bool is_not_entrant() const { return _state == not_entrant; }
344 bool is_zombie() const { return _state == zombie; }
345 bool is_unloaded() const { return _state == unloaded; }
346
347 void clear_unloading_state();
348 virtual bool is_unloading();
349 virtual void do_unloading(bool unloading_occurred);
350
351 #if INCLUDE_RTM_OPT
352 // rtm state accessing and manipulating
353 RTMState rtm_state() const { return _rtm_state; }
354 void set_rtm_state(RTMState state) { _rtm_state = state; }
355 #endif
356
357 void make_in_use() { _state = in_use; }
358 // Make the nmethod non entrant. The nmethod will continue to be
359 // alive. It is used when an uncommon trap happens. Returns true
360 // if this thread changed the state of the nmethod or false if
361 // another thread performed the transition.
362 bool make_not_entrant() {
363 assert(!method()->is_method_handle_intrinsic(), "Cannot make MH intrinsic not entrant");
364 return make_not_entrant_or_zombie(not_entrant);
365 }
366 bool make_not_used() { return make_not_entrant(); }
367 bool make_zombie() { return make_not_entrant_or_zombie(zombie); }
368
369 // used by jvmti to track if the unload event has been reported
370 bool unload_reported() { return _unload_reported; }
371 void set_unload_reported() { _unload_reported = true; }
372
373 int get_state() const {
374 return _state;
375 }
376
377 void make_unloaded();
378
379 bool has_dependencies() { return dependencies_size() != 0; }
380 void flush_dependencies(bool delete_immediately);
381 bool has_flushed_dependencies() { return _has_flushed_dependencies; }
382 void set_has_flushed_dependencies() {
383 assert(!has_flushed_dependencies(), "should only happen once");
384 _has_flushed_dependencies = 1;
385 }
386
387 int comp_level() const { return _comp_level; }
388
389 void unlink_from_method();
390
391 // Support for oops in scopes and relocs:
392 // Note: index 0 is reserved for null.
393 oop oop_at(int index) const;
394 oop* oop_addr_at(int index) const { // for GC
395 // relocation indexes are biased by 1 (because 0 is reserved)
396 assert(index > 0 && index <= oops_count(), "must be a valid non-zero index");
397 assert(!_oops_are_stale, "oops are stale");
398 return &oops_begin()[index - 1];
399 }
400
401 // Support for meta data in scopes and relocs:
402 // Note: index 0 is reserved for null.
403 Metadata* metadata_at(int index) const { return index == 0 ? NULL: *metadata_addr_at(index); }
404 Metadata** metadata_addr_at(int index) const { // for GC
405 // relocation indexes are biased by 1 (because 0 is reserved)
406 assert(index > 0 && index <= metadata_count(), "must be a valid non-zero index");
407 return &metadata_begin()[index - 1];
408 }
409
410 void copy_values(GrowableArray<jobject>* oops);
411 void copy_values(GrowableArray<Metadata*>* metadata);
412
413 // Relocation support
414 private:
415 void fix_oop_relocations(address begin, address end, bool initialize_immediates);
416 inline void initialize_immediate_oop(oop* dest, jobject handle);
417
418 public:
419 void fix_oop_relocations(address begin, address end) { fix_oop_relocations(begin, end, false); }
420 void fix_oop_relocations() { fix_oop_relocations(NULL, NULL, false); }
421
422 // Sweeper support
423 long stack_traversal_mark() { return _stack_traversal_mark; }
424 void set_stack_traversal_mark(long l) { _stack_traversal_mark = l; }
425
426 // implicit exceptions support
427 address continuation_for_implicit_exception(address pc);
428
429 // On-stack replacement support
430 int osr_entry_bci() const { assert(is_osr_method(), "wrong kind of nmethod"); return _entry_bci; }
431 address osr_entry() const { assert(is_osr_method(), "wrong kind of nmethod"); return _osr_entry_point; }
432 void invalidate_osr_method();
433 nmethod* osr_link() const { return _osr_link; }
434 void set_osr_link(nmethod *n) { _osr_link = n; }
435
436 // Verify calls to dead methods have been cleaned.
437 void verify_clean_inline_caches();
438
439 // unlink and deallocate this nmethod
440 // Only NMethodSweeper class is expected to use this. NMethodSweeper is not
441 // expected to use any other private methods/data in this class.
442
443 protected:
444 void flush();
445
446 public:
447 // When true is returned, it is unsafe to remove this nmethod even if
448 // it is a zombie, since the VM or the ServiceThread might still be
449 // using it.
450 bool is_locked_by_vm() const { return _lock_count >0; }
451
452 // See comment at definition of _last_seen_on_stack
453 void mark_as_seen_on_stack();
454 bool can_convert_to_zombie();
455
456 // Evolution support. We make old (discarded) compiled methods point to new Method*s.
457 void set_method(Method* method) { _method = method; }
458
459 #if INCLUDE_JVMCI
460 // Gets the JVMCI name of this nmethod.
461 const char* jvmci_name();
462
463 // Records the pending failed speculation in the
464 // JVMCI speculation log associated with this nmethod.
465 void update_speculation(JavaThread* thread);
466
467 // Gets the data specific to a JVMCI compiled method.
468 // This returns a non-NULL value iff this nmethod was
469 // compiled by the JVMCI compiler.
470 JVMCINMethodData* jvmci_nmethod_data() const {
471 return jvmci_data_size() == 0 ? NULL : (JVMCINMethodData*) jvmci_data_begin();
472 }
473 #endif
474
475 public:
476 void oops_do(OopClosure* f) { oops_do(f, false); }
477 void oops_do(OopClosure* f, bool allow_zombie);
478
479 bool test_set_oops_do_mark();
480 static void oops_do_marking_prologue();
481 static void oops_do_marking_epilogue();
482 static bool oops_do_marking_is_active() { return _oops_do_mark_nmethods != NULL; }
483 bool test_oops_do_mark() { return _oops_do_mark_link != NULL; }
484
485 private:
486 ScopeDesc* scope_desc_in(address begin, address end);
487
488 address* orig_pc_addr(const frame* fr);
489
490 public:
491 // copying of debugging information
492 void copy_scopes_pcs(PcDesc* pcs, int count);
493 void copy_scopes_data(address buffer, int size);
494
495 // Accessor/mutator for the original pc of a frame before a frame was deopted.
496 address get_original_pc(const frame* fr) { return *orig_pc_addr(fr); }
497 void set_original_pc(const frame* fr, address pc) { *orig_pc_addr(fr) = pc; }
498
499 // jvmti support:
500 void post_compiled_method_load_event();
501 jmethodID get_and_cache_jmethod_id();
502
503 // verify operations
504 void verify();
505 void verify_scopes();
506 void verify_interrupt_point(address interrupt_point);
507
508 // printing support
509 void print() const;
510 void print_relocations() PRODUCT_RETURN;
511 void print_pcs() PRODUCT_RETURN;
512 void print_scopes() PRODUCT_RETURN;
513 void print_dependencies() PRODUCT_RETURN;
514 void print_value_on(outputStream* st) const PRODUCT_RETURN;
515 void print_calls(outputStream* st) PRODUCT_RETURN;
516 void print_handler_table() PRODUCT_RETURN;
517 void print_nul_chk_table() PRODUCT_RETURN;
518 void print_recorded_oops() PRODUCT_RETURN;
519 void print_recorded_metadata() PRODUCT_RETURN;
520
521 void maybe_print_nmethod(DirectiveSet* directive);
522 void print_nmethod(bool print_code);
523
524 // need to re-define this from CodeBlob else the overload hides it
525 virtual void print_on(outputStream* st) const { CodeBlob::print_on(st); }
526 void print_on(outputStream* st, const char* msg) const;
527
528 // Logging
529 void log_identity(xmlStream* log) const;
530 void log_new_nmethod() const;
531 void log_state_change() const;
532
533 // Prints block-level comments, including nmethod specific block labels:
534 virtual void print_block_comment(outputStream* stream, address block_begin) const {
535 print_nmethod_labels(stream, block_begin);
536 CodeBlob::print_block_comment(stream, block_begin);
537 }
538 void print_nmethod_labels(outputStream* stream, address block_begin) const;
539
540 // Prints a comment for one native instruction (reloc info, pc desc)
541 void print_code_comment_on(outputStream* st, int column, address begin, address end);
542 static void print_statistics() PRODUCT_RETURN;
543
544 // Compiler task identification. Note that all OSR methods
545 // are numbered in an independent sequence if CICountOSR is true,
546 // and native method wrappers are also numbered independently if
547 // CICountNative is true.
548 virtual int compile_id() const { return _compile_id; }
549 const char* compile_kind() const;
550
551 // tells if any of this method's dependencies have been invalidated
552 // (this is expensive!)
553 static void check_all_dependencies(DepChange& changes);
554
555 // tells if this compiled method is dependent on the given changes,
556 // and the changes have invalidated it
557 bool check_dependency_on(DepChange& changes);
558
559 // Fast breakpoint support. Tells if this compiled method is
560 // dependent on the given method. Returns true if this nmethod
561 // corresponds to the given method as well.
562 virtual bool is_dependent_on_method(Method* dependee);
563
564 // is it ok to patch at address?
565 bool is_patchable_at(address instr_address);
566
567 // UseBiasedLocking support
568 ByteSize native_receiver_sp_offset() {
569 return _native_receiver_sp_offset;
570 }
571 ByteSize native_basic_lock_sp_offset() {
572 return _native_basic_lock_sp_offset;
573 }
574
575 // support for code generation
576 static int verified_entry_point_offset() { return offset_of(nmethod, _verified_entry_point); }
577 static int osr_entry_point_offset() { return offset_of(nmethod, _osr_entry_point); }
578 static int state_offset() { return offset_of(nmethod, _state); }
579
580 virtual void metadata_do(MetadataClosure* f);
581
582 NativeCallWrapper* call_wrapper_at(address call) const;
583 NativeCallWrapper* call_wrapper_before(address return_pc) const;
584 address call_instruction_address(address pc) const;
585
586 virtual CompiledStaticCall* compiledStaticCall_at(Relocation* call_site) const;
587 virtual CompiledStaticCall* compiledStaticCall_at(address addr) const;
588 virtual CompiledStaticCall* compiledStaticCall_before(address addr) const;
589 };
590
591 // Locks an nmethod so its code will not get removed and it will not
592 // be made into a zombie, even if it is a not_entrant method. After the
593 // nmethod becomes a zombie, if CompiledMethodUnload event processing
594 // needs to be done, then lock_nmethod() is used directly to keep the
595 // generated code from being reused too early.
596 class nmethodLocker : public StackObj {
597 CompiledMethod* _nm;
598
599 public:
600
601 // note: nm can be NULL
602 // Only JvmtiDeferredEvent::compiled_method_unload_event()
603 // should pass zombie_ok == true.
604 static void lock_nmethod(CompiledMethod* nm, bool zombie_ok = false);
605 static void unlock_nmethod(CompiledMethod* nm); // (ditto)
606
607 nmethodLocker(address pc); // derive nm from pc
608 nmethodLocker(nmethod *nm) { _nm = nm; lock_nmethod(_nm); }
609 nmethodLocker(CompiledMethod *nm) {
610 _nm = nm;
611 lock(_nm);
612 }
613
614 static void lock(CompiledMethod* method) {
615 if (method == NULL) return;
616 lock_nmethod(method);
617 }
618
619 static void unlock(CompiledMethod* method) {
620 if (method == NULL) return;
621 unlock_nmethod(method);
622 }
623
624 nmethodLocker() { _nm = NULL; }
625 ~nmethodLocker() {
626 unlock(_nm);
627 }
628
629 CompiledMethod* code() { return _nm; }
630 void set_code(CompiledMethod* new_nm) {
631 unlock(_nm); // note: This works even if _nm==new_nm.
632 _nm = new_nm;
633 lock(_nm);
634 }
635 };
636
637 #endif // SHARE_CODE_NMETHOD_HPP