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.
22 *
23 */
24
25 #ifndef SHARE_CODE_NMETHOD_HPP
26 #define SHARE_CODE_NMETHOD_HPP
27
28 #include "code/compiledMethod.hpp"
29 #include "compiler/compilerDefinitions.hpp"
30
31 class DepChange;
32 class DirectiveSet;
33 class DebugInformationRecorder;
34
35 // nmethods (native methods) are the compiled code versions of Java methods.
36 //
37 // An nmethod contains:
38 // - header (the nmethod structure)
39 // [Relocation]
40 // - relocation information
41 // - constant part (doubles, longs and floats used in nmethod)
42 // - oop table
43 // [Code]
44 // - code body
45 // - exception handler
46 // - stub code
47 // [Debugging information]
48 // - oop array
49 // - data array
50 // - pcs
51 // [Exception handler table]
52 // - handler entry point array
53 // [Implicit Null Pointer exception table]
54 // - implicit null table array
55 // [Speculations]
56 // - encoded speculations array
57 // [JVMCINMethodData]
58 // - meta data for JVMCI compiled nmethod
59
60 #if INCLUDE_JVMCI
61 class FailedSpeculation;
62 class JVMCINMethodData;
63 #endif
64
65 class nmethod : public CompiledMethod {
66 friend class VMStructs;
67 friend class JVMCIVMStructs;
68 friend class NMethodSweeper;
69 friend class CodeCache; // scavengable oops
70 friend class JVMCINMethodData;
71 private:
72
73 // Shared fields for all nmethod's
74 int _entry_bci; // != InvocationEntryBci if this nmethod is an on-stack replacement method
75 jmethodID _jmethod_id; // Cache of method()->jmethod_id()
76
77 // To support simple linked-list chaining of nmethods:
78 nmethod* _osr_link; // from InstanceKlass::osr_nmethods_head
79
80 static nmethod* volatile _oops_do_mark_nmethods;
81 nmethod* volatile _oops_do_mark_link;
82
83 // offsets for entry points
84 address _entry_point; // entry point with class check
85 address _verified_entry_point; // entry point without class check
86 address _verified_value_entry_point; // value type entry point (unpack all value args) without class check
87 address _verified_value_ro_entry_point; // value type entry point (unpack receiver only) without class check
88 address _osr_entry_point; // entry point for on stack replacement
89
90 // Offsets for different nmethod parts
91 int _exception_offset;
92 // Offset of the unwind handler if it exists
93 int _unwind_handler_offset;
94
95 int _consts_offset;
96 int _stub_offset;
97 int _oops_offset; // offset to where embedded oop table begins (inside data)
98 int _metadata_offset; // embedded meta data table
99 int _scopes_data_offset;
100 int _scopes_pcs_offset;
101 int _dependencies_offset;
102 int _handler_table_offset;
103 int _nul_chk_table_offset;
104 #if INCLUDE_JVMCI
105 int _speculations_offset;
106 int _jvmci_data_offset;
107 #endif
108 int _nmethod_end_offset;
109
110 int code_offset() const { return (address) code_begin() - header_begin(); }
111
112 // location in frame (offset for sp) that deopt can store the original
113 // pc during a deopt.
114 int _orig_pc_offset;
115
116 int _compile_id; // which compilation made this nmethod
117 int _comp_level; // compilation level
118
119 // protected by CodeCache_lock
120 bool _has_flushed_dependencies; // Used for maintenance of dependencies (CodeCache_lock)
121
122 // used by jvmti to track if an unload event has been posted for this nmethod.
123 bool _unload_reported;
124
125 // Protected by Patching_lock
126 volatile signed char _state; // {not_installed, in_use, not_entrant, zombie, unloaded}
127
128 #ifdef ASSERT
129 bool _oops_are_stale; // indicates that it's no longer safe to access oops section
130 #endif
131
132 #if INCLUDE_RTM_OPT
133 // RTM state at compile time. Used during deoptimization to decide
134 // whether to restart collecting RTM locking abort statistic again.
135 RTMState _rtm_state;
136 #endif
137
138 // Nmethod Flushing lock. If non-zero, then the nmethod is not removed
139 // and is not made into a zombie. However, once the nmethod is made into
140 // a zombie, it will be locked one final time if CompiledMethodUnload
141 // event processing needs to be done.
142 volatile jint _lock_count;
143
144 // not_entrant method removal. Each mark_sweep pass will update
145 // this mark to current sweep invocation count if it is seen on the
146 // stack. An not_entrant method can be removed when there are no
147 // more activations, i.e., when the _stack_traversal_mark is less than
148 // current sweep traversal index.
149 volatile long _stack_traversal_mark;
150
151 // The _hotness_counter indicates the hotness of a method. The higher
152 // the value the hotter the method. The hotness counter of a nmethod is
153 // set to [(ReservedCodeCacheSize / (1024 * 1024)) * 2] each time the method
154 // is active while stack scanning (mark_active_nmethods()). The hotness
155 // counter is decreased (by 1) while sweeping.
156 int _hotness_counter;
157
158 // Local state used to keep track of whether unloading is happening or not
159 volatile uint8_t _is_unloading_state;
160
161 // These are used for compiled synchronized native methods to
162 // locate the owner and stack slot for the BasicLock so that we can
163 // properly revoke the bias of the owner if necessary. They are
164 // needed because there is no debug information for compiled native
165 // wrappers and the oop maps are insufficient to allow
166 // frame::retrieve_receiver() to work. Currently they are expected
167 // to be byte offsets from the Java stack pointer for maximum code
168 // sharing between platforms. Note that currently biased locking
169 // will never cause Class instances to be biased but this code
170 // handles the static synchronized case as well.
171 // JVMTI's GetLocalInstance() also uses these offsets to find the receiver
172 // for non-static native wrapper frames.
173 ByteSize _native_receiver_sp_offset;
174 ByteSize _native_basic_lock_sp_offset;
175
176 friend class nmethodLocker;
177
178 // For native wrappers
179 nmethod(Method* method,
180 CompilerType type,
181 int nmethod_size,
182 int compile_id,
183 CodeOffsets* offsets,
184 CodeBuffer *code_buffer,
185 int frame_size,
186 ByteSize basic_lock_owner_sp_offset, /* synchronized natives only */
187 ByteSize basic_lock_sp_offset, /* synchronized natives only */
188 OopMapSet* oop_maps);
189
190 // Creation support
191 nmethod(Method* method,
192 CompilerType type,
193 int nmethod_size,
194 int compile_id,
195 int entry_bci,
196 CodeOffsets* offsets,
197 int orig_pc_offset,
198 DebugInformationRecorder *recorder,
199 Dependencies* dependencies,
200 CodeBuffer *code_buffer,
201 int frame_size,
202 OopMapSet* oop_maps,
203 ExceptionHandlerTable* handler_table,
204 ImplicitExceptionTable* nul_chk_table,
205 AbstractCompiler* compiler,
206 int comp_level
207 #if INCLUDE_JVMCI
208 , char* speculations,
209 int speculations_len,
210 int jvmci_data_size
211 #endif
212 );
213
214 // helper methods
215 void* operator new(size_t size, int nmethod_size, int comp_level) throw();
216
217 const char* reloc_string_for(u_char* begin, u_char* end);
218 // Returns true if this thread changed the state of the nmethod or
219 // false if another thread performed the transition.
220 bool make_not_entrant_or_zombie(int state);
221 bool make_entrant() { Unimplemented(); return false; }
222 void inc_decompile_count();
223
224 // Inform external interfaces that a compiled method has been unloaded
225 void post_compiled_method_unload();
226
227 // Initailize fields to their default values
228 void init_defaults();
229
230 // Offsets
231 int content_offset() const { return content_begin() - header_begin(); }
232 int data_offset() const { return _data_offset; }
233
234 address header_end() const { return (address) header_begin() + header_size(); }
235
236 public:
237 // create nmethod with entry_bci
238 static nmethod* new_nmethod(const methodHandle& method,
239 int compile_id,
240 int entry_bci,
241 CodeOffsets* offsets,
242 int orig_pc_offset,
243 DebugInformationRecorder* recorder,
244 Dependencies* dependencies,
245 CodeBuffer *code_buffer,
246 int frame_size,
247 OopMapSet* oop_maps,
248 ExceptionHandlerTable* handler_table,
249 ImplicitExceptionTable* nul_chk_table,
250 AbstractCompiler* compiler,
251 int comp_level
252 #if INCLUDE_JVMCI
253 , char* speculations = NULL,
254 int speculations_len = 0,
255 int nmethod_mirror_index = -1,
256 const char* nmethod_mirror_name = NULL,
257 FailedSpeculation** failed_speculations = NULL
258 #endif
259 );
260
261 // Only used for unit tests.
262 nmethod()
263 : CompiledMethod(),
264 _is_unloading_state(0),
265 _native_receiver_sp_offset(in_ByteSize(-1)),
266 _native_basic_lock_sp_offset(in_ByteSize(-1)) {}
267
268
269 static nmethod* new_native_nmethod(const methodHandle& method,
270 int compile_id,
271 CodeBuffer *code_buffer,
272 int vep_offset,
273 int frame_complete,
274 int frame_size,
275 ByteSize receiver_sp_offset,
276 ByteSize basic_lock_sp_offset,
277 OopMapSet* oop_maps);
278
279 // type info
280 bool is_nmethod() const { return true; }
281 bool is_osr_method() const { return _entry_bci != InvocationEntryBci; }
282
283 // boundaries for different parts
284 address consts_begin () const { return header_begin() + _consts_offset ; }
285 address consts_end () const { return code_begin() ; }
286 address stub_begin () const { return header_begin() + _stub_offset ; }
287 address stub_end () const { return header_begin() + _oops_offset ; }
288 address exception_begin () const { return header_begin() + _exception_offset ; }
289 address unwind_handler_begin () const { return _unwind_handler_offset != -1 ? (header_begin() + _unwind_handler_offset) : NULL; }
290 oop* oops_begin () const { return (oop*) (header_begin() + _oops_offset) ; }
291 oop* oops_end () const { return (oop*) (header_begin() + _metadata_offset) ; }
292
293 Metadata** metadata_begin () const { return (Metadata**) (header_begin() + _metadata_offset) ; }
294 Metadata** metadata_end () const { return (Metadata**) _scopes_data_begin; }
295
296 address scopes_data_end () const { return header_begin() + _scopes_pcs_offset ; }
297 PcDesc* scopes_pcs_begin () const { return (PcDesc*)(header_begin() + _scopes_pcs_offset ); }
298 PcDesc* scopes_pcs_end () const { return (PcDesc*)(header_begin() + _dependencies_offset) ; }
299 address dependencies_begin () const { return header_begin() + _dependencies_offset ; }
300 address dependencies_end () const { return header_begin() + _handler_table_offset ; }
301 address handler_table_begin () const { return header_begin() + _handler_table_offset ; }
302 address handler_table_end () const { return header_begin() + _nul_chk_table_offset ; }
303 address nul_chk_table_begin () const { return header_begin() + _nul_chk_table_offset ; }
304 #if INCLUDE_JVMCI
305 address nul_chk_table_end () const { return header_begin() + _speculations_offset ; }
306 address speculations_begin () const { return header_begin() + _speculations_offset ; }
307 address speculations_end () const { return header_begin() + _jvmci_data_offset ; }
308 address jvmci_data_begin () const { return header_begin() + _jvmci_data_offset ; }
309 address jvmci_data_end () const { return header_begin() + _nmethod_end_offset ; }
310 #else
311 address nul_chk_table_end () const { return header_begin() + _nmethod_end_offset ; }
312 #endif
313
314 // Sizes
315 int oops_size () const { return (address) oops_end () - (address) oops_begin (); }
316 int metadata_size () const { return (address) metadata_end () - (address) metadata_begin (); }
317 int dependencies_size () const { return dependencies_end () - dependencies_begin (); }
318 #if INCLUDE_JVMCI
319 int speculations_size () const { return speculations_end () - speculations_begin (); }
320 int jvmci_data_size () const { return jvmci_data_end () - jvmci_data_begin (); }
321 #endif
322
323 int oops_count() const { assert(oops_size() % oopSize == 0, ""); return (oops_size() / oopSize) + 1; }
324 int metadata_count() const { assert(metadata_size() % wordSize == 0, ""); return (metadata_size() / wordSize) + 1; }
325
326 int total_size () const;
327
328 void dec_hotness_counter() { _hotness_counter--; }
329 void set_hotness_counter(int val) { _hotness_counter = val; }
330 int hotness_counter() const { return _hotness_counter; }
331
332 // Containment
333 bool oops_contains (oop* addr) const { return oops_begin () <= addr && addr < oops_end (); }
334 bool metadata_contains (Metadata** addr) const { return metadata_begin () <= addr && addr < metadata_end (); }
335 bool scopes_data_contains (address addr) const { return scopes_data_begin () <= addr && addr < scopes_data_end (); }
336 bool scopes_pcs_contains (PcDesc* addr) const { return scopes_pcs_begin () <= addr && addr < scopes_pcs_end (); }
337
338 // entry points
339 address entry_point() const { return _entry_point; } // normal entry point
340 address verified_entry_point() const { return _verified_entry_point; } // normal entry point without class check
341 address verified_value_entry_point() const { return _verified_value_entry_point; } // value type entry point (unpack all value args) without class check
342 address verified_value_ro_entry_point() const { return _verified_value_ro_entry_point; } // value type entry point (only unpack receiver) without class check
343
344 // flag accessing and manipulation
345 bool is_not_installed() const { return _state == not_installed; }
346 bool is_in_use() const { return _state <= in_use; }
347 bool is_alive() const { return _state < zombie; }
348 bool is_not_entrant() const { return _state == not_entrant; }
349 bool is_zombie() const { return _state == zombie; }
350 bool is_unloaded() const { return _state == unloaded; }
351
352 void clear_unloading_state();
353 virtual bool is_unloading();
354 virtual void do_unloading(bool unloading_occurred);
355
356 #if INCLUDE_RTM_OPT
357 // rtm state accessing and manipulating
358 RTMState rtm_state() const { return _rtm_state; }
359 void set_rtm_state(RTMState state) { _rtm_state = state; }
360 #endif
361
362 void make_in_use() { _state = in_use; }
363 // Make the nmethod non entrant. The nmethod will continue to be
364 // alive. It is used when an uncommon trap happens. Returns true
365 // if this thread changed the state of the nmethod or false if
366 // another thread performed the transition.
367 bool make_not_entrant() {
368 assert(!method()->is_method_handle_intrinsic(), "Cannot make MH intrinsic not entrant");
369 return make_not_entrant_or_zombie(not_entrant);
370 }
371 bool make_not_used() { return make_not_entrant(); }
372 bool make_zombie() { return make_not_entrant_or_zombie(zombie); }
373
374 // used by jvmti to track if the unload event has been reported
375 bool unload_reported() { return _unload_reported; }
376 void set_unload_reported() { _unload_reported = true; }
377
378 int get_state() const {
379 return _state;
380 }
381
382 void make_unloaded();
383
384 bool has_dependencies() { return dependencies_size() != 0; }
385 void flush_dependencies(bool delete_immediately);
386 bool has_flushed_dependencies() { return _has_flushed_dependencies; }
387 void set_has_flushed_dependencies() {
388 assert(!has_flushed_dependencies(), "should only happen once");
389 _has_flushed_dependencies = 1;
390 }
391
392 int comp_level() const { return _comp_level; }
393 void unlink_from_method(bool acquire_lock);
394
395 // Support for oops in scopes and relocs:
396 // Note: index 0 is reserved for null.
397 oop oop_at(int index) const;
398 oop* oop_addr_at(int index) const { // for GC
399 // relocation indexes are biased by 1 (because 0 is reserved)
400 assert(index > 0 && index <= oops_count(), "must be a valid non-zero index");
401 assert(!_oops_are_stale, "oops are stale");
402 return &oops_begin()[index - 1];
403 }
404
405 // Support for meta data in scopes and relocs:
406 // Note: index 0 is reserved for null.
407 Metadata* metadata_at(int index) const { return index == 0 ? NULL: *metadata_addr_at(index); }
408 Metadata** metadata_addr_at(int index) const { // for GC
409 // relocation indexes are biased by 1 (because 0 is reserved)
410 assert(index > 0 && index <= metadata_count(), "must be a valid non-zero index");
411 return &metadata_begin()[index - 1];
412 }
413
414 void copy_values(GrowableArray<jobject>* oops);
415 void copy_values(GrowableArray<Metadata*>* metadata);
416
417 // Relocation support
418 private:
419 void fix_oop_relocations(address begin, address end, bool initialize_immediates);
420 inline void initialize_immediate_oop(oop* dest, jobject handle);
421
422 public:
423 void fix_oop_relocations(address begin, address end) { fix_oop_relocations(begin, end, false); }
424 void fix_oop_relocations() { fix_oop_relocations(NULL, NULL, false); }
425
426 // Sweeper support
427 long stack_traversal_mark() { return _stack_traversal_mark; }
428 void set_stack_traversal_mark(long l) { _stack_traversal_mark = l; }
429
430 // implicit exceptions support
431 address continuation_for_implicit_exception(address pc);
432
433 // On-stack replacement support
434 int osr_entry_bci() const { assert(is_osr_method(), "wrong kind of nmethod"); return _entry_bci; }
435 address osr_entry() const { assert(is_osr_method(), "wrong kind of nmethod"); return _osr_entry_point; }
436 void invalidate_osr_method();
437 nmethod* osr_link() const { return _osr_link; }
438 void set_osr_link(nmethod *n) { _osr_link = n; }
439
440 // Verify calls to dead methods have been cleaned.
441 void verify_clean_inline_caches();
442
443 // unlink and deallocate this nmethod
444 // Only NMethodSweeper class is expected to use this. NMethodSweeper is not
445 // expected to use any other private methods/data in this class.
446
447 protected:
448 void flush();
449
450 public:
451 // When true is returned, it is unsafe to remove this nmethod even if
452 // it is a zombie, since the VM or the ServiceThread might still be
453 // using it.
454 bool is_locked_by_vm() const { return _lock_count >0; }
455
456 // See comment at definition of _last_seen_on_stack
457 void mark_as_seen_on_stack();
458 bool can_convert_to_zombie();
459
460 // Evolution support. We make old (discarded) compiled methods point to new Method*s.
461 void set_method(Method* method) { _method = method; }
462
463 #if INCLUDE_JVMCI
464 // Gets the JVMCI name of this nmethod.
465 const char* jvmci_name();
466
467 // Records the pending failed speculation in the
468 // JVMCI speculation log associated with this nmethod.
469 void update_speculation(JavaThread* thread);
470
471 // Gets the data specific to a JVMCI compiled method.
472 // This returns a non-NULL value iff this nmethod was
473 // compiled by the JVMCI compiler.
474 JVMCINMethodData* jvmci_nmethod_data() const {
475 return jvmci_data_size() == 0 ? NULL : (JVMCINMethodData*) jvmci_data_begin();
476 }
477 #endif
478
479 public:
480 void oops_do(OopClosure* f) { oops_do(f, false); }
481 void oops_do(OopClosure* f, bool allow_zombie);
482
483 bool test_set_oops_do_mark();
484 static void oops_do_marking_prologue();
485 static void oops_do_marking_epilogue();
486 static bool oops_do_marking_is_active() { return _oops_do_mark_nmethods != NULL; }
487 bool test_oops_do_mark() { return _oops_do_mark_link != NULL; }
488
489 private:
490 ScopeDesc* scope_desc_in(address begin, address end);
491
492 address* orig_pc_addr(const frame* fr);
493
494 public:
495 // copying of debugging information
496 void copy_scopes_pcs(PcDesc* pcs, int count);
497 void copy_scopes_data(address buffer, int size);
498
499 // Accessor/mutator for the original pc of a frame before a frame was deopted.
500 address get_original_pc(const frame* fr) { return *orig_pc_addr(fr); }
501 void set_original_pc(const frame* fr, address pc) { *orig_pc_addr(fr) = pc; }
502
503 // jvmti support:
504 void post_compiled_method_load_event();
505 jmethodID get_and_cache_jmethod_id();
506
507 // verify operations
508 void verify();
509 void verify_scopes();
510 void verify_interrupt_point(address interrupt_point);
511
512 // printing support
513 void print() const;
514 void print_relocations() PRODUCT_RETURN;
515 void print_pcs() PRODUCT_RETURN;
516 void print_scopes() PRODUCT_RETURN;
517 void print_dependencies() PRODUCT_RETURN;
518 void print_value_on(outputStream* st) const PRODUCT_RETURN;
519 void print_calls(outputStream* st) PRODUCT_RETURN;
520 void print_handler_table() PRODUCT_RETURN;
521 void print_nul_chk_table() PRODUCT_RETURN;
522 void print_recorded_oops() PRODUCT_RETURN;
523 void print_recorded_metadata() PRODUCT_RETURN;
524
525 void maybe_print_nmethod(DirectiveSet* directive);
526 void print_nmethod(bool print_code);
527
528 // need to re-define this from CodeBlob else the overload hides it
529 virtual void print_on(outputStream* st) const { CodeBlob::print_on(st); }
530 void print_on(outputStream* st, const char* msg) const;
531
532 // Logging
533 void log_identity(xmlStream* log) const;
534 void log_new_nmethod() const;
535 void log_state_change() const;
536
537 // Prints block-level comments, including nmethod specific block labels:
538 virtual void print_block_comment(outputStream* stream, address block_begin) const {
539 print_nmethod_labels(stream, block_begin);
540 CodeBlob::print_block_comment(stream, block_begin);
541 }
542 void print_nmethod_labels(outputStream* stream, address block_begin) const;
543 void print_entry_parameters(outputStream* stream, address block_begin) const;
544
545 // Prints a comment for one native instruction (reloc info, pc desc)
546 void print_code_comment_on(outputStream* st, int column, address begin, address end);
547 static void print_statistics() PRODUCT_RETURN;
548
549 // Compiler task identification. Note that all OSR methods
550 // are numbered in an independent sequence if CICountOSR is true,
551 // and native method wrappers are also numbered independently if
552 // CICountNative is true.
553 virtual int compile_id() const { return _compile_id; }
554 const char* compile_kind() const;
555
556 // tells if any of this method's dependencies have been invalidated
557 // (this is expensive!)
558 static void check_all_dependencies(DepChange& changes);
559
560 // tells if this compiled method is dependent on the given changes,
561 // and the changes have invalidated it
562 bool check_dependency_on(DepChange& changes);
563
564 // Fast breakpoint support. Tells if this compiled method is
565 // dependent on the given method. Returns true if this nmethod
566 // corresponds to the given method as well.
567 virtual bool is_dependent_on_method(Method* dependee);
568
569 // is it ok to patch at address?
570 bool is_patchable_at(address instr_address);
571
572 // UseBiasedLocking support
573 ByteSize native_receiver_sp_offset() {
574 return _native_receiver_sp_offset;
575 }
576 ByteSize native_basic_lock_sp_offset() {
577 return _native_basic_lock_sp_offset;
578 }
579
580 // support for code generation
581 static int verified_entry_point_offset() { return offset_of(nmethod, _verified_entry_point); }
582 static int osr_entry_point_offset() { return offset_of(nmethod, _osr_entry_point); }
583 static int state_offset() { return offset_of(nmethod, _state); }
584
585 virtual void metadata_do(MetadataClosure* f);
586
587 NativeCallWrapper* call_wrapper_at(address call) const;
588 NativeCallWrapper* call_wrapper_before(address return_pc) const;
589 address call_instruction_address(address pc) const;
590
591 virtual CompiledStaticCall* compiledStaticCall_at(Relocation* call_site) const;
592 virtual CompiledStaticCall* compiledStaticCall_at(address addr) const;
593 virtual CompiledStaticCall* compiledStaticCall_before(address addr) const;
594 };
595
596 // Locks an nmethod so its code will not get removed and it will not
597 // be made into a zombie, even if it is a not_entrant method. After the
598 // nmethod becomes a zombie, if CompiledMethodUnload event processing
599 // needs to be done, then lock_nmethod() is used directly to keep the
600 // generated code from being reused too early.
601 class nmethodLocker : public StackObj {
602 CompiledMethod* _nm;
603
604 public:
605
606 // note: nm can be NULL
607 // Only JvmtiDeferredEvent::compiled_method_unload_event()
608 // should pass zombie_ok == true.
609 static void lock_nmethod(CompiledMethod* nm, bool zombie_ok = false);
610 static void unlock_nmethod(CompiledMethod* nm); // (ditto)
611
612 nmethodLocker(address pc); // derive nm from pc
613 nmethodLocker(nmethod *nm) { _nm = nm; lock_nmethod(_nm); }
614 nmethodLocker(CompiledMethod *nm) {
615 _nm = nm;
616 lock(_nm);
617 }
618
619 static void lock(CompiledMethod* method) {
620 if (method == NULL) return;
621 lock_nmethod(method);
622 }
623
624 static void unlock(CompiledMethod* method) {
625 if (method == NULL) return;
626 unlock_nmethod(method);
627 }
628
629 nmethodLocker() { _nm = NULL; }
630 ~nmethodLocker() {
631 unlock(_nm);
632 }
633
634 CompiledMethod* code() { return _nm; }
635 void set_code(CompiledMethod* new_nm) {
636 unlock(_nm); // note: This works even if _nm==new_nm.
637 _nm = new_nm;
638 lock(_nm);
639 }
640 };
641
642 #endif // SHARE_CODE_NMETHOD_HPP