1 /*
2 * Copyright (c) 1997, 2016, 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_VM_CODE_NMETHOD_HPP
26 #define SHARE_VM_CODE_NMETHOD_HPP
27
28 #include "code/compiledMethod.hpp"
29
30 class DepChange;
31 class DirectiveSet;
32
33 // nmethods (native methods) are the compiled code versions of Java methods.
34 //
35 // An nmethod contains:
36 // - header (the nmethod structure)
37 // [Relocation]
38 // - relocation information
39 // - constant part (doubles, longs and floats used in nmethod)
40 // - oop table
41 // [Code]
42 // - code body
43 // - exception handler
44 // - stub code
45 // [Debugging information]
46 // - oop array
47 // - data array
48 // - pcs
49 // [Exception handler table]
50 // - handler entry point array
51 // [Implicit Null Pointer exception table]
52 // - implicit null table array
53
54 class nmethod : public CompiledMethod {
55 friend class VMStructs;
56 friend class JVMCIVMStructs;
57 friend class NMethodSweeper;
58 friend class CodeCache; // scavengable oops
59 private:
60
61 // Shared fields for all nmethod's
62 int _entry_bci; // != InvocationEntryBci if this nmethod is an on-stack replacement method
63 jmethodID _jmethod_id; // Cache of method()->jmethod_id()
64
65 #if INCLUDE_JVMCI
66 // Needed to keep nmethods alive that are not the default nmethod for the associated Method.
67 oop _jvmci_installed_code;
68 oop _speculation_log;
69 #endif
70
71 // To support simple linked-list chaining of nmethods:
72 nmethod* _osr_link; // from InstanceKlass::osr_nmethods_head
73
74 static nmethod* volatile _oops_do_mark_nmethods;
75 nmethod* volatile _oops_do_mark_link;
76
77 AbstractCompiler* _compiler; // The compiler which compiled this nmethod
78
79 // offsets for entry points
80 address _entry_point; // entry point with class check
81 address _verified_entry_point; // entry point without class check
82 address _osr_entry_point; // entry point for on stack replacement
83
84 // Offsets for different nmethod parts
85 int _exception_offset;
86 // Offset of the unwind handler if it exists
87 int _unwind_handler_offset;
88
89 int _consts_offset;
90 int _stub_offset;
91 int _oops_offset; // offset to where embedded oop table begins (inside data)
92 int _metadata_offset; // embedded meta data table
93 int _scopes_data_offset;
94 int _scopes_pcs_offset;
95 int _dependencies_offset;
96 int _handler_table_offset;
97 int _nul_chk_table_offset;
98 int _nmethod_end_offset;
99
100 int code_offset() const { return (address) code_begin() - header_begin(); }
101
102 // location in frame (offset for sp) that deopt can store the original
103 // pc during a deopt.
104 int _orig_pc_offset;
105
106 int _compile_id; // which compilation made this nmethod
107 int _comp_level; // compilation level
108
109 // protected by CodeCache_lock
110 bool _has_flushed_dependencies; // Used for maintenance of dependencies (CodeCache_lock)
111
112 // used by jvmti to track if an unload event has been posted for this nmethod.
113 bool _unload_reported;
114
115 // Protected by Patching_lock
116 volatile unsigned char _state; // {in_use, not_entrant, zombie, unloaded}
117
118 #ifdef ASSERT
119 bool _oops_are_stale; // indicates that it's no longer safe to access oops section
120 #endif
121
122 jbyte _scavenge_root_state;
123
124 #if INCLUDE_RTM_OPT
125 // RTM state at compile time. Used during deoptimization to decide
126 // whether to restart collecting RTM locking abort statistic again.
127 RTMState _rtm_state;
128 #endif
129
130 // Nmethod Flushing lock. If non-zero, then the nmethod is not removed
131 // and is not made into a zombie. However, once the nmethod is made into
132 // a zombie, it will be locked one final time if CompiledMethodUnload
133 // event processing needs to be done.
134 volatile jint _lock_count;
135
136 // not_entrant method removal. Each mark_sweep pass will update
137 // this mark to current sweep invocation count if it is seen on the
138 // stack. An not_entrant method can be removed when there are no
139 // more activations, i.e., when the _stack_traversal_mark is less than
140 // current sweep traversal index.
141 long _stack_traversal_mark;
142
143 // The _hotness_counter indicates the hotness of a method. The higher
144 // the value the hotter the method. The hotness counter of a nmethod is
145 // set to [(ReservedCodeCacheSize / (1024 * 1024)) * 2] each time the method
146 // is active while stack scanning (mark_active_nmethods()). The hotness
147 // counter is decreased (by 1) while sweeping.
148 int _hotness_counter;
149
150 // These are used for compiled synchronized native methods to
151 // locate the owner and stack slot for the BasicLock so that we can
152 // properly revoke the bias of the owner if necessary. They are
153 // needed because there is no debug information for compiled native
154 // wrappers and the oop maps are insufficient to allow
155 // frame::retrieve_receiver() to work. Currently they are expected
156 // to be byte offsets from the Java stack pointer for maximum code
157 // sharing between platforms. Note that currently biased locking
158 // will never cause Class instances to be biased but this code
159 // handles the static synchronized case as well.
160 // JVMTI's GetLocalInstance() also uses these offsets to find the receiver
161 // for non-static native wrapper frames.
162 ByteSize _native_receiver_sp_offset;
163 ByteSize _native_basic_lock_sp_offset;
164
165 friend class nmethodLocker;
166
167 // For native wrappers
168 nmethod(Method* method,
169 int nmethod_size,
170 int compile_id,
171 CodeOffsets* offsets,
172 CodeBuffer *code_buffer,
173 int frame_size,
174 ByteSize basic_lock_owner_sp_offset, /* synchronized natives only */
175 ByteSize basic_lock_sp_offset, /* synchronized natives only */
176 OopMapSet* oop_maps);
177
178 // Creation support
179 nmethod(Method* method,
180 int nmethod_size,
181 int compile_id,
182 int entry_bci,
183 CodeOffsets* offsets,
184 int orig_pc_offset,
185 DebugInformationRecorder *recorder,
186 Dependencies* dependencies,
187 CodeBuffer *code_buffer,
188 int frame_size,
189 OopMapSet* oop_maps,
190 ExceptionHandlerTable* handler_table,
191 ImplicitExceptionTable* nul_chk_table,
192 AbstractCompiler* compiler,
193 int comp_level
194 #if INCLUDE_JVMCI
195 , Handle installed_code,
196 Handle speculation_log
197 #endif
198 );
199
200 // helper methods
201 void* operator new(size_t size, int nmethod_size, int comp_level) throw();
202
203 const char* reloc_string_for(u_char* begin, u_char* end);
204 // Returns true if this thread changed the state of the nmethod or
205 // false if another thread performed the transition.
206 bool make_not_entrant_or_zombie(unsigned int state);
207 bool make_entrant() { Unimplemented(); return false; }
208 void inc_decompile_count();
209
210 // Inform external interfaces that a compiled method has been unloaded
211 void post_compiled_method_unload();
212
213 // Initailize fields to their default values
214 void init_defaults();
215
216 // Offsets
217 int content_offset() const { return content_begin() - header_begin(); }
218 int data_offset() const { return _data_offset; }
219
220 address header_end() const { return (address) header_begin() + header_size(); }
221
222 public:
223 // create nmethod with entry_bci
224 static nmethod* new_nmethod(const methodHandle& method,
225 int compile_id,
226 int entry_bci,
227 CodeOffsets* offsets,
228 int orig_pc_offset,
229 DebugInformationRecorder* recorder,
230 Dependencies* dependencies,
231 CodeBuffer *code_buffer,
232 int frame_size,
233 OopMapSet* oop_maps,
234 ExceptionHandlerTable* handler_table,
235 ImplicitExceptionTable* nul_chk_table,
236 AbstractCompiler* compiler,
237 int comp_level
238 #if INCLUDE_JVMCI
239 , Handle installed_code = Handle(),
240 Handle speculation_log = Handle()
241 #endif
242 );
243
244 static nmethod* new_native_nmethod(const methodHandle& method,
245 int compile_id,
246 CodeBuffer *code_buffer,
247 int vep_offset,
248 int frame_complete,
249 int frame_size,
250 ByteSize receiver_sp_offset,
251 ByteSize basic_lock_sp_offset,
252 OopMapSet* oop_maps);
253
254 // accessors
255 AbstractCompiler* compiler() const { return _compiler; }
256
257 // type info
258 bool is_nmethod() const { return true; }
259 bool is_osr_method() const { return _entry_bci != InvocationEntryBci; }
260
261 bool is_compiled_by_c1() const;
262 bool is_compiled_by_jvmci() const;
263 bool is_compiled_by_c2() const;
264 bool is_compiled_by_shark() const;
265
266 // boundaries for different parts
267 address consts_begin () const { return header_begin() + _consts_offset ; }
268 address consts_end () const { return code_begin() ; }
269 address stub_begin () const { return header_begin() + _stub_offset ; }
270 address stub_end () const { return header_begin() + _oops_offset ; }
271 address exception_begin () const { return header_begin() + _exception_offset ; }
272 address unwind_handler_begin () const { return _unwind_handler_offset != -1 ? (header_begin() + _unwind_handler_offset) : NULL; }
273 oop* oops_begin () const { return (oop*) (header_begin() + _oops_offset) ; }
274 oop* oops_end () const { return (oop*) (header_begin() + _metadata_offset) ; }
275
276 Metadata** metadata_begin () const { return (Metadata**) (header_begin() + _metadata_offset) ; }
277 Metadata** metadata_end () const { return (Metadata**) _scopes_data_begin; }
278
279 address scopes_data_end () const { return header_begin() + _scopes_pcs_offset ; }
280 PcDesc* scopes_pcs_begin () const { return (PcDesc*)(header_begin() + _scopes_pcs_offset ); }
281 PcDesc* scopes_pcs_end () const { return (PcDesc*)(header_begin() + _dependencies_offset) ; }
282 address dependencies_begin () const { return header_begin() + _dependencies_offset ; }
283 address dependencies_end () const { return header_begin() + _handler_table_offset ; }
284 address handler_table_begin () const { return header_begin() + _handler_table_offset ; }
285 address handler_table_end () const { return header_begin() + _nul_chk_table_offset ; }
286 address nul_chk_table_begin () const { return header_begin() + _nul_chk_table_offset ; }
287 address nul_chk_table_end () const { return header_begin() + _nmethod_end_offset ; }
288
289 // Sizes
290 int oops_size () const { return (address) oops_end () - (address) oops_begin (); }
291 int metadata_size () const { return (address) metadata_end () - (address) metadata_begin (); }
292 int dependencies_size () const { return dependencies_end () - dependencies_begin (); }
293
294 int oops_count() const { assert(oops_size() % oopSize == 0, ""); return (oops_size() / oopSize) + 1; }
295 int metadata_count() const { assert(metadata_size() % wordSize == 0, ""); return (metadata_size() / wordSize) + 1; }
296
297 int total_size () const;
298
299 void dec_hotness_counter() { _hotness_counter--; }
300 void set_hotness_counter(int val) { _hotness_counter = val; }
301 int hotness_counter() const { return _hotness_counter; }
302
303 // Containment
304 bool oops_contains (oop* addr) const { return oops_begin () <= addr && addr < oops_end (); }
305 bool metadata_contains (Metadata** addr) const { return metadata_begin () <= addr && addr < metadata_end (); }
306 bool scopes_data_contains (address addr) const { return scopes_data_begin () <= addr && addr < scopes_data_end (); }
307 bool scopes_pcs_contains (PcDesc* addr) const { return scopes_pcs_begin () <= addr && addr < scopes_pcs_end (); }
308
309 // entry points
310 address entry_point() const { return _entry_point; } // normal entry point
311 address verified_entry_point() const { return _verified_entry_point; } // if klass is correct
312
313 enum { in_use = 0, // executable nmethod
314 not_entrant = 1, // marked for deoptimization but activations may still exist,
315 // will be transformed to zombie when all activations are gone
316 zombie = 2, // no activations exist, nmethod is ready for purge
317 unloaded = 3 }; // there should be no activations, should not be called,
318 // will be transformed to zombie immediately
319
320 // flag accessing and manipulation
321 bool is_in_use() const { return _state == in_use; }
322 bool is_alive() const { unsigned char s = _state; return s < zombie; }
323 bool is_not_entrant() const { return _state == not_entrant; }
324 bool is_zombie() const { return _state == zombie; }
325 bool is_unloaded() const { return _state == unloaded; }
326
327 #if INCLUDE_RTM_OPT
328 // rtm state accessing and manipulating
329 RTMState rtm_state() const { return _rtm_state; }
330 void set_rtm_state(RTMState state) { _rtm_state = state; }
331 #endif
332
333 // Make the nmethod non entrant. The nmethod will continue to be
334 // alive. It is used when an uncommon trap happens. Returns true
335 // if this thread changed the state of the nmethod or false if
336 // another thread performed the transition.
337 bool make_not_entrant() {
338 assert(!method()->is_method_handle_intrinsic(), "Cannot make MH intrinsic not entrant");
339 return make_not_entrant_or_zombie(not_entrant);
340 }
341 bool make_not_used() { return make_not_entrant(); }
342 bool make_zombie() { return make_not_entrant_or_zombie(zombie); }
343
344 // used by jvmti to track if the unload event has been reported
345 bool unload_reported() { return _unload_reported; }
346 void set_unload_reported() { _unload_reported = true; }
347
348 int get_state() const {
349 return _state;
350 }
351
352 void make_unloaded(BoolObjectClosure* is_alive, oop cause);
353
354 bool has_dependencies() { return dependencies_size() != 0; }
355 void flush_dependencies(BoolObjectClosure* is_alive);
356 bool has_flushed_dependencies() { return _has_flushed_dependencies; }
357 void set_has_flushed_dependencies() {
358 assert(!has_flushed_dependencies(), "should only happen once");
359 _has_flushed_dependencies = 1;
360 }
361
362 int comp_level() const { return _comp_level; }
363
364 // Support for oops in scopes and relocs:
365 // Note: index 0 is reserved for null.
366 oop oop_at(int index) const { return index == 0 ? (oop) NULL: *oop_addr_at(index); }
367 oop* oop_addr_at(int index) const { // for GC
368 // relocation indexes are biased by 1 (because 0 is reserved)
369 assert(index > 0 && index <= oops_count(), "must be a valid non-zero index");
370 assert(!_oops_are_stale, "oops are stale");
371 return &oops_begin()[index - 1];
372 }
373
374 // Support for meta data in scopes and relocs:
375 // Note: index 0 is reserved for null.
376 Metadata* metadata_at(int index) const { return index == 0 ? NULL: *metadata_addr_at(index); }
377 Metadata** metadata_addr_at(int index) const { // for GC
378 // relocation indexes are biased by 1 (because 0 is reserved)
379 assert(index > 0 && index <= metadata_count(), "must be a valid non-zero index");
380 return &metadata_begin()[index - 1];
381 }
382
383 void copy_values(GrowableArray<jobject>* oops);
384 void copy_values(GrowableArray<Metadata*>* metadata);
385
386 // Relocation support
387 private:
388 void fix_oop_relocations(address begin, address end, bool initialize_immediates);
389 inline void initialize_immediate_oop(oop* dest, jobject handle);
390
391 public:
392 void fix_oop_relocations(address begin, address end) { fix_oop_relocations(begin, end, false); }
393 void fix_oop_relocations() { fix_oop_relocations(NULL, NULL, false); }
394
395 // Scavengable oop support
396 bool on_scavenge_root_list() const { return (_scavenge_root_state & 1) != 0; }
397 protected:
398 enum { sl_on_list = 0x01, sl_marked = 0x10 };
399 void set_on_scavenge_root_list() { _scavenge_root_state = sl_on_list; }
400 void clear_on_scavenge_root_list() { _scavenge_root_state = 0; }
401 // assertion-checking and pruning logic uses the bits of _scavenge_root_state
402 #ifndef PRODUCT
403 void set_scavenge_root_marked() { _scavenge_root_state |= sl_marked; }
404 void clear_scavenge_root_marked() { _scavenge_root_state &= ~sl_marked; }
405 bool scavenge_root_not_marked() { return (_scavenge_root_state &~ sl_on_list) == 0; }
406 // N.B. there is no positive marked query, and we only use the not_marked query for asserts.
407 #endif //PRODUCT
408 nmethod* scavenge_root_link() const { return _scavenge_root_link; }
409 void set_scavenge_root_link(nmethod *n) { _scavenge_root_link = n; }
410
411 public:
412
413 // Sweeper support
414 long stack_traversal_mark() { return _stack_traversal_mark; }
415 void set_stack_traversal_mark(long l) { _stack_traversal_mark = l; }
416
417 // implicit exceptions support
418 address continuation_for_implicit_exception(address pc);
419
420 // On-stack replacement support
421 int osr_entry_bci() const { assert(is_osr_method(), "wrong kind of nmethod"); return _entry_bci; }
422 address osr_entry() const { assert(is_osr_method(), "wrong kind of nmethod"); return _osr_entry_point; }
423 void invalidate_osr_method();
424 nmethod* osr_link() const { return _osr_link; }
425 void set_osr_link(nmethod *n) { _osr_link = n; }
426
427 // Verify calls to dead methods have been cleaned.
428 void verify_clean_inline_caches();
429
430 // unlink and deallocate this nmethod
431 // Only NMethodSweeper class is expected to use this. NMethodSweeper is not
432 // expected to use any other private methods/data in this class.
433
434 protected:
435 void flush();
436
437 public:
438 // When true is returned, it is unsafe to remove this nmethod even if
439 // it is a zombie, since the VM or the ServiceThread might still be
440 // using it.
441 bool is_locked_by_vm() const { return _lock_count >0; }
442
443 // See comment at definition of _last_seen_on_stack
444 void mark_as_seen_on_stack();
445 bool can_convert_to_zombie();
446
447 // Evolution support. We make old (discarded) compiled methods point to new Method*s.
448 void set_method(Method* method) { _method = method; }
449
450 #if INCLUDE_JVMCI
451 oop jvmci_installed_code() { return _jvmci_installed_code ; }
452 char* jvmci_installed_code_name(char* buf, size_t buflen);
453
454 // Update the state of any InstalledCode instance associated with
455 // this nmethod based on the current value of _state.
456 void maybe_invalidate_installed_code();
457
458 // Helper function to invalidate InstalledCode instances
459 static void invalidate_installed_code(Handle installed_code, TRAPS);
460
461 oop speculation_log() { return _speculation_log ; }
462
463 private:
464 void clear_jvmci_installed_code();
465
466 public:
467 #endif
468
469 protected:
470 virtual bool do_unloading_oops(address low_boundary, BoolObjectClosure* is_alive, bool unloading_occurred);
471 #if INCLUDE_JVMCI
472 virtual bool do_unloading_jvmci(BoolObjectClosure* is_alive, bool unloading_occurred);
473 #endif
474
475 private:
476 bool do_unloading_scopes(BoolObjectClosure* is_alive, bool unloading_occurred);
477 // Unload a nmethod if the *root object is dead.
478 bool can_unload(BoolObjectClosure* is_alive, oop* root, bool unloading_occurred);
479 bool unload_if_dead_at(RelocIterator *iter_at_oop, BoolObjectClosure* is_alive, bool unloading_occurred);
480
481 public:
482 void oops_do(OopClosure* f) { oops_do(f, false); }
483 void oops_do(OopClosure* f, bool allow_zombie);
484 bool detect_scavenge_root_oops();
485 void verify_scavenge_root_oops() PRODUCT_RETURN;
486
487 bool test_set_oops_do_mark();
488 static void oops_do_marking_prologue();
489 static void oops_do_marking_epilogue();
490 static bool oops_do_marking_is_active() { return _oops_do_mark_nmethods != NULL; }
491 bool test_oops_do_mark() { return _oops_do_mark_link != NULL; }
492
493 private:
494 ScopeDesc* scope_desc_in(address begin, address end);
495
496 address* orig_pc_addr(const frame* fr) { return (address*) ((address)fr->unextended_sp() + _orig_pc_offset); }
497
498 public:
499 // copying of debugging information
500 void copy_scopes_pcs(PcDesc* pcs, int count);
501 void copy_scopes_data(address buffer, int size);
502
503 // Accessor/mutator for the original pc of a frame before a frame was deopted.
504 address get_original_pc(const frame* fr) { return *orig_pc_addr(fr); }
505 void set_original_pc(const frame* fr, address pc) { *orig_pc_addr(fr) = pc; }
506
507 // jvmti support:
508 void post_compiled_method_load_event();
509 jmethodID get_and_cache_jmethod_id();
510
511 // verify operations
512 void verify();
513 void verify_scopes();
514 void verify_interrupt_point(address interrupt_point);
515
516 // printing support
517 void print() const;
518 void print_relocations() PRODUCT_RETURN;
519 void print_pcs() PRODUCT_RETURN;
520 void print_scopes() PRODUCT_RETURN;
521 void print_dependencies() PRODUCT_RETURN;
522 void print_value_on(outputStream* st) const PRODUCT_RETURN;
523 void print_calls(outputStream* st) PRODUCT_RETURN;
524 void print_handler_table() PRODUCT_RETURN;
525 void print_nul_chk_table() PRODUCT_RETURN;
526 void print_recorded_oops() PRODUCT_RETURN;
527 void print_recorded_metadata() PRODUCT_RETURN;
528
529 void maybe_print_nmethod(DirectiveSet* directive);
530 void print_nmethod(bool print_code);
531
532 // need to re-define this from CodeBlob else the overload hides it
533 virtual void print_on(outputStream* st) const { CodeBlob::print_on(st); }
534 void print_on(outputStream* st, const char* msg) const;
535
536 // Logging
537 void log_identity(xmlStream* log) const;
538 void log_new_nmethod() const;
539 void log_state_change() const;
540
541 // Prints block-level comments, including nmethod specific block labels:
542 virtual void print_block_comment(outputStream* stream, address block_begin) const {
543 print_nmethod_labels(stream, block_begin);
544 CodeBlob::print_block_comment(stream, block_begin);
545 }
546 void print_nmethod_labels(outputStream* stream, address block_begin) const;
547
548 // Prints a comment for one native instruction (reloc info, pc desc)
549 void print_code_comment_on(outputStream* st, int column, address begin, address end);
550 static void print_statistics() PRODUCT_RETURN;
551
552 // Compiler task identification. Note that all OSR methods
553 // are numbered in an independent sequence if CICountOSR is true,
554 // and native method wrappers are also numbered independently if
555 // CICountNative is true.
556 virtual int compile_id() const { return _compile_id; }
557 const char* compile_kind() const;
558
559 // tells if any of this method's dependencies have been invalidated
560 // (this is expensive!)
561 static void check_all_dependencies(DepChange& changes);
562
563 // tells if this compiled method is dependent on the given changes,
564 // and the changes have invalidated it
565 bool check_dependency_on(DepChange& changes);
566
567 // Evolution support. Tells if this compiled method is dependent on any of
568 // methods m() of class dependee, such that if m() in dependee is replaced,
569 // this compiled method will have to be deoptimized.
570 bool is_evol_dependent_on(Klass* dependee);
571
572 // Fast breakpoint support. Tells if this compiled method is
573 // dependent on the given method. Returns true if this nmethod
574 // corresponds to the given method as well.
575 virtual bool is_dependent_on_method(Method* dependee);
576
577 // is it ok to patch at address?
578 bool is_patchable_at(address instr_address);
579
580 // UseBiasedLocking support
581 ByteSize native_receiver_sp_offset() {
582 return _native_receiver_sp_offset;
583 }
584 ByteSize native_basic_lock_sp_offset() {
585 return _native_basic_lock_sp_offset;
586 }
587
588 // support for code generation
589 static int verified_entry_point_offset() { return offset_of(nmethod, _verified_entry_point); }
590 static int osr_entry_point_offset() { return offset_of(nmethod, _osr_entry_point); }
591 static int state_offset() { return offset_of(nmethod, _state); }
592
593 virtual void metadata_do(void f(Metadata*));
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_VM_CODE_NMETHOD_HPP