1 /*
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  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.
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  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  *
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 18  *
 19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 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   // A weak reference to an InstalledCode object associated with
 67   // this nmethod.
 68   jweak     _jvmci_installed_code;
 69 
 70   // A weak reference to a SpeculationLog object associated with
 71   // this nmethod.
 72   jweak     _speculation_log;
 73 
 74   // Determines whether this nmethod is unloaded when the
 75   // referent in _jvmci_installed_code is cleared. This
 76   // will be false if the referent is initialized to a
 77   // HotSpotNMethod object whose isDefault field is true.
 78   // That is, installed code other than a "default"
 79   // HotSpotNMethod causes nmethod unloading.
 80   // This field is ignored once _jvmci_installed_code is NULL.
 81   bool _jvmci_installed_code_triggers_invalidation;
 82 #endif
 83 
 84   // To support simple linked-list chaining of nmethods:
 85   nmethod*  _osr_link;         // from InstanceKlass::osr_nmethods_head
 86 
 87   static nmethod* volatile _oops_do_mark_nmethods;
 88   nmethod*        volatile _oops_do_mark_link;
 89 
 90   // offsets for entry points
 91   address _entry_point;                      // entry point with class check
 92   address _verified_entry_point;             // entry point without class check
 93   address _osr_entry_point;                  // entry point for on stack replacement
 94 
 95   // Offsets for different nmethod parts
 96   int  _exception_offset;
 97   // Offset of the unwind handler if it exists
 98   int _unwind_handler_offset;
 99 
100   int _consts_offset;
101   int _stub_offset;
102   int _oops_offset;                       // offset to where embedded oop table begins (inside data)
103   int _metadata_offset;                   // embedded meta data table
104   int _scopes_data_offset;
105   int _scopes_pcs_offset;
106   int _dependencies_offset;
107   int _handler_table_offset;
108   int _nul_chk_table_offset;
109   int _nmethod_end_offset;
110 
111   int code_offset() const { return (address) code_begin() - header_begin(); }
112 
113   // location in frame (offset for sp) that deopt can store the original
114   // pc during a deopt.
115   int _orig_pc_offset;
116 
117   int _compile_id;                           // which compilation made this nmethod
118   int _comp_level;                           // compilation level
119 
120   // protected by CodeCache_lock
121   bool _has_flushed_dependencies;            // Used for maintenance of dependencies (CodeCache_lock)
122 
123   // used by jvmti to track if an unload event has been posted for this nmethod.
124   bool _unload_reported;
125 
126   // Protected by Patching_lock
127   volatile signed char _state;               // {not_installed, in_use, not_entrant, zombie, unloaded}
128 
129 #ifdef ASSERT
130   bool _oops_are_stale;  // indicates that it's no longer safe to access oops section
131 #endif
132 
133   jbyte _scavenge_root_state;
134 
135 #if INCLUDE_RTM_OPT
136   // RTM state at compile time. Used during deoptimization to decide
137   // whether to restart collecting RTM locking abort statistic again.
138   RTMState _rtm_state;
139 #endif
140 
141   // Nmethod Flushing lock. If non-zero, then the nmethod is not removed
142   // and is not made into a zombie. However, once the nmethod is made into
143   // a zombie, it will be locked one final time if CompiledMethodUnload
144   // event processing needs to be done.
145   volatile jint _lock_count;
146 
147   // not_entrant method removal. Each mark_sweep pass will update
148   // this mark to current sweep invocation count if it is seen on the
149   // stack.  An not_entrant method can be removed when there are no
150   // more activations, i.e., when the _stack_traversal_mark is less than
151   // current sweep traversal index.
152   volatile long _stack_traversal_mark;
153 
154   // The _hotness_counter indicates the hotness of a method. The higher
155   // the value the hotter the method. The hotness counter of a nmethod is
156   // set to [(ReservedCodeCacheSize / (1024 * 1024)) * 2] each time the method
157   // is active while stack scanning (mark_active_nmethods()). The hotness
158   // counter is decreased (by 1) while sweeping.
159   int _hotness_counter;
160 
161   // Local state used to keep track of whether unloading is happening or not
162   volatile uint8_t _is_unloading_state;
163 
164   // These are used for compiled synchronized native methods to
165   // locate the owner and stack slot for the BasicLock so that we can
166   // properly revoke the bias of the owner if necessary. They are
167   // needed because there is no debug information for compiled native
168   // wrappers and the oop maps are insufficient to allow
169   // frame::retrieve_receiver() to work. Currently they are expected
170   // to be byte offsets from the Java stack pointer for maximum code
171   // sharing between platforms. Note that currently biased locking
172   // will never cause Class instances to be biased but this code
173   // handles the static synchronized case as well.
174   // JVMTI's GetLocalInstance() also uses these offsets to find the receiver
175   // for non-static native wrapper frames.
176   ByteSize _native_receiver_sp_offset;
177   ByteSize _native_basic_lock_sp_offset;
178 
179   friend class nmethodLocker;
180 
181   // For native wrappers
182   nmethod(Method* method,
183           CompilerType type,
184           int nmethod_size,
185           int compile_id,
186           CodeOffsets* offsets,
187           CodeBuffer *code_buffer,
188           int frame_size,
189           ByteSize basic_lock_owner_sp_offset, /* synchronized natives only */
190           ByteSize basic_lock_sp_offset,       /* synchronized natives only */
191           OopMapSet* oop_maps);
192 
193   // Creation support
194   nmethod(Method* method,
195           CompilerType type,
196           int nmethod_size,
197           int compile_id,
198           int entry_bci,
199           CodeOffsets* offsets,
200           int orig_pc_offset,
201           DebugInformationRecorder *recorder,
202           Dependencies* dependencies,
203           CodeBuffer *code_buffer,
204           int frame_size,
205           OopMapSet* oop_maps,
206           ExceptionHandlerTable* handler_table,
207           ImplicitExceptionTable* nul_chk_table,
208           AbstractCompiler* compiler,
209           int comp_level
210 #if INCLUDE_JVMCI
211           , jweak installed_code,
212           jweak speculation_log
213 #endif
214           );
215 
216   // helper methods
217   void* operator new(size_t size, int nmethod_size, int comp_level) throw();
218 
219   const char* reloc_string_for(u_char* begin, u_char* end);
220   // Returns true if this thread changed the state of the nmethod or
221   // false if another thread performed the transition.
222   bool make_not_entrant_or_zombie(int state);
223   bool make_entrant() { Unimplemented(); return false; }
224   void inc_decompile_count();
225 
226   // Inform external interfaces that a compiled method has been unloaded
227   void post_compiled_method_unload();
228 
229   // Initailize fields to their default values
230   void init_defaults();
231 
232   // Offsets
233   int content_offset() const                  { return content_begin() - header_begin(); }
234   int data_offset() const                     { return _data_offset; }
235 
236   address header_end() const                  { return (address)    header_begin() + header_size(); }
237 
238  public:
239   // create nmethod with entry_bci
240   static nmethod* new_nmethod(const methodHandle& method,
241                               int compile_id,
242                               int entry_bci,
243                               CodeOffsets* offsets,
244                               int orig_pc_offset,
245                               DebugInformationRecorder* recorder,
246                               Dependencies* dependencies,
247                               CodeBuffer *code_buffer,
248                               int frame_size,
249                               OopMapSet* oop_maps,
250                               ExceptionHandlerTable* handler_table,
251                               ImplicitExceptionTable* nul_chk_table,
252                               AbstractCompiler* compiler,
253                               int comp_level
254 #if INCLUDE_JVMCI
255                               , jweak installed_code = NULL,
256                               jweak speculation_log = NULL
257 #endif
258   );
259 
260   // Only used for unit tests.
261   nmethod()
262     : CompiledMethod(),
263       _is_unloading_state(0),
264       _native_receiver_sp_offset(in_ByteSize(-1)),
265       _native_basic_lock_sp_offset(in_ByteSize(-1)) {}
266 
267 
268   static nmethod* new_native_nmethod(const methodHandle& method,
269                                      int compile_id,
270                                      CodeBuffer *code_buffer,
271                                      int vep_offset,
272                                      int frame_complete,
273                                      int frame_size,
274                                      ByteSize receiver_sp_offset,
275                                      ByteSize basic_lock_sp_offset,
276                                      OopMapSet* oop_maps);
277 
278   // type info
279   bool is_nmethod() const                         { return true; }
280   bool is_osr_method() const                      { return _entry_bci != InvocationEntryBci; }
281 
282   // boundaries for different parts
283   address consts_begin          () const          { return           header_begin() + _consts_offset        ; }
284   address consts_end            () const          { return           code_begin()                           ; }
285   address stub_begin            () const          { return           header_begin() + _stub_offset          ; }
286   address stub_end              () const          { return           header_begin() + _oops_offset          ; }
287   address exception_begin       () const          { return           header_begin() + _exception_offset     ; }
288   address unwind_handler_begin  () const          { return _unwind_handler_offset != -1 ? (header_begin() + _unwind_handler_offset) : NULL; }
289   oop*    oops_begin            () const          { return (oop*)   (header_begin() + _oops_offset)         ; }
290   oop*    oops_end              () const          { return (oop*)   (header_begin() + _metadata_offset)     ; }
291 
292   Metadata** metadata_begin   () const            { return (Metadata**)  (header_begin() + _metadata_offset)     ; }
293   Metadata** metadata_end     () const            { return (Metadata**)  _scopes_data_begin; }
294 
295   address scopes_data_end       () const          { return           header_begin() + _scopes_pcs_offset    ; }
296   PcDesc* scopes_pcs_begin      () const          { return (PcDesc*)(header_begin() + _scopes_pcs_offset   ); }
297   PcDesc* scopes_pcs_end        () const          { return (PcDesc*)(header_begin() + _dependencies_offset) ; }
298   address dependencies_begin    () const          { return           header_begin() + _dependencies_offset  ; }
299   address dependencies_end      () const          { return           header_begin() + _handler_table_offset ; }
300   address handler_table_begin   () const          { return           header_begin() + _handler_table_offset ; }
301   address handler_table_end     () const          { return           header_begin() + _nul_chk_table_offset ; }
302   address nul_chk_table_begin   () const          { return           header_begin() + _nul_chk_table_offset ; }
303   address nul_chk_table_end     () const          { return           header_begin() + _nmethod_end_offset   ; }
304 
305   // Sizes
306   int oops_size         () const                  { return (address)  oops_end         () - (address)  oops_begin         (); }
307   int metadata_size     () const                  { return (address)  metadata_end     () - (address)  metadata_begin     (); }
308   int dependencies_size () const                  { return            dependencies_end () -            dependencies_begin (); }
309 
310   int     oops_count() const { assert(oops_size() % oopSize == 0, "");  return (oops_size() / oopSize) + 1; }
311   int metadata_count() const { assert(metadata_size() % wordSize == 0, ""); return (metadata_size() / wordSize) + 1; }
312 
313   int total_size        () const;
314 
315   void dec_hotness_counter()        { _hotness_counter--; }
316   void set_hotness_counter(int val) { _hotness_counter = val; }
317   int  hotness_counter() const      { return _hotness_counter; }
318 
319   // Containment
320   bool oops_contains         (oop*    addr) const { return oops_begin         () <= addr && addr < oops_end         (); }
321   bool metadata_contains     (Metadata** addr) const   { return metadata_begin     () <= addr && addr < metadata_end     (); }
322   bool scopes_data_contains  (address addr) const { return scopes_data_begin  () <= addr && addr < scopes_data_end  (); }
323   bool scopes_pcs_contains   (PcDesc* addr) const { return scopes_pcs_begin   () <= addr && addr < scopes_pcs_end   (); }
324 
325   // entry points
326   address entry_point() const                     { return _entry_point;             } // normal entry point
327   address verified_entry_point() const            { return _verified_entry_point;    } // if klass is correct
328 
329   // flag accessing and manipulation
330   bool  is_not_installed() const                  { return _state == not_installed; }
331   bool  is_in_use() const                         { return _state <= in_use; }
332   bool  is_alive() const                          { return _state < zombie; }
333   bool  is_not_entrant() const                    { return _state == not_entrant; }
334   bool  is_zombie() const                         { return _state == zombie; }
335   bool  is_unloaded() const                       { return _state == unloaded; }
336 
337   void clear_unloading_state();
338   virtual bool is_unloading();
339   virtual void do_unloading(bool unloading_occurred);
340 
341 #if INCLUDE_RTM_OPT
342   // rtm state accessing and manipulating
343   RTMState  rtm_state() const                     { return _rtm_state; }
344   void set_rtm_state(RTMState state)              { _rtm_state = state; }
345 #endif
346 
347   void make_in_use()                              { _state = in_use; }
348   // Make the nmethod non entrant. The nmethod will continue to be
349   // alive.  It is used when an uncommon trap happens.  Returns true
350   // if this thread changed the state of the nmethod or false if
351   // another thread performed the transition.
352   bool  make_not_entrant() {
353     assert(!method()->is_method_handle_intrinsic(), "Cannot make MH intrinsic not entrant");
354     return make_not_entrant_or_zombie(not_entrant);
355   }
356   bool  make_not_used()    { return make_not_entrant(); }
357   bool  make_zombie()      { return make_not_entrant_or_zombie(zombie); }
358 
359   // used by jvmti to track if the unload event has been reported
360   bool  unload_reported()                         { return _unload_reported; }
361   void  set_unload_reported()                     { _unload_reported = true; }
362 
363   int get_state() const {
364     return _state;
365   }
366 
367   void  make_unloaded();
368 
369   bool has_dependencies()                         { return dependencies_size() != 0; }
370   void flush_dependencies(bool delete_immediately);
371   bool has_flushed_dependencies()                 { return _has_flushed_dependencies; }
372   void set_has_flushed_dependencies()             {
373     assert(!has_flushed_dependencies(), "should only happen once");
374     _has_flushed_dependencies = 1;
375   }
376 
377   int   comp_level() const                        { return _comp_level; }
378 
379   // Support for oops in scopes and relocs:
380   // Note: index 0 is reserved for null.
381   oop   oop_at(int index) const;
382   oop*  oop_addr_at(int index) const {  // for GC
383     // relocation indexes are biased by 1 (because 0 is reserved)
384     assert(index > 0 && index <= oops_count(), "must be a valid non-zero index");
385     assert(!_oops_are_stale, "oops are stale");
386     return &oops_begin()[index - 1];
387   }
388 
389   // Support for meta data in scopes and relocs:
390   // Note: index 0 is reserved for null.
391   Metadata*     metadata_at(int index) const      { return index == 0 ? NULL: *metadata_addr_at(index); }
392   Metadata**  metadata_addr_at(int index) const {  // for GC
393     // relocation indexes are biased by 1 (because 0 is reserved)
394     assert(index > 0 && index <= metadata_count(), "must be a valid non-zero index");
395     return &metadata_begin()[index - 1];
396   }
397 
398   void copy_values(GrowableArray<jobject>* oops);
399   void copy_values(GrowableArray<Metadata*>* metadata);
400 
401   // Relocation support
402 private:
403   void fix_oop_relocations(address begin, address end, bool initialize_immediates);
404   inline void initialize_immediate_oop(oop* dest, jobject handle);
405 
406 public:
407   void fix_oop_relocations(address begin, address end) { fix_oop_relocations(begin, end, false); }
408   void fix_oop_relocations()                           { fix_oop_relocations(NULL, NULL, false); }
409 
410   // Scavengable oop support
411   bool  on_scavenge_root_list() const                  { return (_scavenge_root_state & 1) != 0; }
412  protected:
413   enum { sl_on_list = 0x01, sl_marked = 0x10 };
414   void  set_on_scavenge_root_list()                    { _scavenge_root_state = sl_on_list; }
415   void  clear_on_scavenge_root_list()                  { _scavenge_root_state = 0; }
416   // assertion-checking and pruning logic uses the bits of _scavenge_root_state
417 #ifndef PRODUCT
418   void  set_scavenge_root_marked()                     { _scavenge_root_state |= sl_marked; }
419   void  clear_scavenge_root_marked()                   { _scavenge_root_state &= ~sl_marked; }
420   bool  scavenge_root_not_marked()                     { return (_scavenge_root_state &~ sl_on_list) == 0; }
421   // N.B. there is no positive marked query, and we only use the not_marked query for asserts.
422 #endif //PRODUCT
423   nmethod* scavenge_root_link() const                  { return _scavenge_root_link; }
424   void     set_scavenge_root_link(nmethod *n)          { _scavenge_root_link = n; }
425 
426  public:
427 
428   // Sweeper support
429   long  stack_traversal_mark()                    { return _stack_traversal_mark; }
430   void  set_stack_traversal_mark(long l)          { _stack_traversal_mark = l; }
431 
432   // implicit exceptions support
433   address continuation_for_implicit_exception(address pc);
434 
435   // On-stack replacement support
436   int   osr_entry_bci() const                     { assert(is_osr_method(), "wrong kind of nmethod"); return _entry_bci; }
437   address  osr_entry() const                      { assert(is_osr_method(), "wrong kind of nmethod"); return _osr_entry_point; }
438   void  invalidate_osr_method();
439   nmethod* osr_link() const                       { return _osr_link; }
440   void     set_osr_link(nmethod *n)               { _osr_link = n; }
441 
442   // Verify calls to dead methods have been cleaned.
443   void verify_clean_inline_caches();
444 
445   // unlink and deallocate this nmethod
446   // Only NMethodSweeper class is expected to use this. NMethodSweeper is not
447   // expected to use any other private methods/data in this class.
448 
449  protected:
450   void flush();
451 
452  public:
453   // When true is returned, it is unsafe to remove this nmethod even if
454   // it is a zombie, since the VM or the ServiceThread might still be
455   // using it.
456   bool is_locked_by_vm() const                    { return _lock_count >0; }
457 
458   // See comment at definition of _last_seen_on_stack
459   void mark_as_seen_on_stack();
460   bool can_convert_to_zombie();
461 
462   // Evolution support. We make old (discarded) compiled methods point to new Method*s.
463   void set_method(Method* method) { _method = method; }
464 
465 #if INCLUDE_JVMCI
466   // Gets the InstalledCode object associated with this nmethod
467   // which may be NULL if this nmethod was not compiled by JVMCI
468   // or the weak reference has been cleared.
469   oop jvmci_installed_code();
470 
471   // Copies the value of the name field in the InstalledCode
472   // object (if any) associated with this nmethod into buf.
473   // Returns the value of buf if it was updated otherwise NULL.
474   char* jvmci_installed_code_name(char* buf, size_t buflen) const;
475 
476   // Updates the state of the InstalledCode (if any) associated with
477   // this nmethod based on the current value of _state.
478   void maybe_invalidate_installed_code();
479 
480   // Deoptimizes the nmethod (if any) in the address field of a given
481   // InstalledCode object. The address field is zeroed upon return.
482   static void invalidate_installed_code(Handle installed_code, TRAPS);
483 
484   // Gets the SpeculationLog object associated with this nmethod
485   // which may be NULL if this nmethod was not compiled by JVMCI
486   // or the weak reference has been cleared.
487   oop speculation_log();
488 
489  private:
490   // Deletes the weak reference (if any) to the InstalledCode object
491   // associated with this nmethod.
492   void clear_jvmci_installed_code();
493 
494   // Deletes the weak reference (if any) to the SpeculationLog object
495   // associated with this nmethod.
496   void clear_speculation_log();
497 
498  public:
499 #endif
500 
501  public:
502   void oops_do(OopClosure* f) { oops_do(f, false); }
503   void oops_do(OopClosure* f, bool allow_zombie);
504   bool detect_scavenge_root_oops();
505   void verify_scavenge_root_oops() PRODUCT_RETURN;
506 
507   bool test_set_oops_do_mark();
508   static void oops_do_marking_prologue();
509   static void oops_do_marking_epilogue();
510   static bool oops_do_marking_is_active() { return _oops_do_mark_nmethods != NULL; }
511   bool test_oops_do_mark() { return _oops_do_mark_link != NULL; }
512 
513  private:
514   ScopeDesc* scope_desc_in(address begin, address end);
515 
516   address* orig_pc_addr(const frame* fr);
517 
518  public:
519   // copying of debugging information
520   void copy_scopes_pcs(PcDesc* pcs, int count);
521   void copy_scopes_data(address buffer, int size);
522 
523   // Accessor/mutator for the original pc of a frame before a frame was deopted.
524   address get_original_pc(const frame* fr) { return *orig_pc_addr(fr); }
525   void    set_original_pc(const frame* fr, address pc) { *orig_pc_addr(fr) = pc; }
526 
527   // jvmti support:
528   void post_compiled_method_load_event();
529   jmethodID get_and_cache_jmethod_id();
530 
531   // verify operations
532   void verify();
533   void verify_scopes();
534   void verify_interrupt_point(address interrupt_point);
535 
536   // printing support
537   void print()                          const;
538   void print_relocations()                        PRODUCT_RETURN;
539   void print_pcs()                                PRODUCT_RETURN;
540   void print_scopes()                             PRODUCT_RETURN;
541   void print_dependencies()                       PRODUCT_RETURN;
542   void print_value_on(outputStream* st) const     PRODUCT_RETURN;
543   void print_calls(outputStream* st)              PRODUCT_RETURN;
544   void print_handler_table()                      PRODUCT_RETURN;
545   void print_nul_chk_table()                      PRODUCT_RETURN;
546   void print_recorded_oops()                      PRODUCT_RETURN;
547   void print_recorded_metadata()                  PRODUCT_RETURN;
548 
549   void maybe_print_nmethod(DirectiveSet* directive);
550   void print_nmethod(bool print_code);
551 
552   // need to re-define this from CodeBlob else the overload hides it
553   virtual void print_on(outputStream* st) const { CodeBlob::print_on(st); }
554   void print_on(outputStream* st, const char* msg) const;
555 
556   // Logging
557   void log_identity(xmlStream* log) const;
558   void log_new_nmethod() const;
559   void log_state_change() const;
560 
561   // Prints block-level comments, including nmethod specific block labels:
562   virtual void print_block_comment(outputStream* stream, address block_begin) const {
563     print_nmethod_labels(stream, block_begin);
564     CodeBlob::print_block_comment(stream, block_begin);
565   }
566   void print_nmethod_labels(outputStream* stream, address block_begin) const;
567 
568   // Prints a comment for one native instruction (reloc info, pc desc)
569   void print_code_comment_on(outputStream* st, int column, address begin, address end);
570   static void print_statistics() PRODUCT_RETURN;
571 
572   // Compiler task identification.  Note that all OSR methods
573   // are numbered in an independent sequence if CICountOSR is true,
574   // and native method wrappers are also numbered independently if
575   // CICountNative is true.
576   virtual int compile_id() const { return _compile_id; }
577   const char* compile_kind() const;
578 
579   // tells if any of this method's dependencies have been invalidated
580   // (this is expensive!)
581   static void check_all_dependencies(DepChange& changes);
582 
583   // tells if this compiled method is dependent on the given changes,
584   // and the changes have invalidated it
585   bool check_dependency_on(DepChange& changes);
586 
587   // Evolution support. Tells if this compiled method is dependent on any of
588   // methods m() of class dependee, such that if m() in dependee is replaced,
589   // this compiled method will have to be deoptimized.
590   bool is_evol_dependent_on(Klass* dependee);
591 
592   // Fast breakpoint support. Tells if this compiled method is
593   // dependent on the given method. Returns true if this nmethod
594   // corresponds to the given method as well.
595   virtual bool is_dependent_on_method(Method* dependee);
596 
597   // is it ok to patch at address?
598   bool is_patchable_at(address instr_address);
599 
600   // UseBiasedLocking support
601   ByteSize native_receiver_sp_offset() {
602     return _native_receiver_sp_offset;
603   }
604   ByteSize native_basic_lock_sp_offset() {
605     return _native_basic_lock_sp_offset;
606   }
607 
608   // support for code generation
609   static int verified_entry_point_offset()        { return offset_of(nmethod, _verified_entry_point); }
610   static int osr_entry_point_offset()             { return offset_of(nmethod, _osr_entry_point); }
611   static int state_offset()                       { return offset_of(nmethod, _state); }
612 
613   virtual void metadata_do(void f(Metadata*));
614 
615   NativeCallWrapper* call_wrapper_at(address call) const;
616   NativeCallWrapper* call_wrapper_before(address return_pc) const;
617   address call_instruction_address(address pc) const;
618 
619   virtual CompiledStaticCall* compiledStaticCall_at(Relocation* call_site) const;
620   virtual CompiledStaticCall* compiledStaticCall_at(address addr) const;
621   virtual CompiledStaticCall* compiledStaticCall_before(address addr) const;
622 };
623 
624 // Locks an nmethod so its code will not get removed and it will not
625 // be made into a zombie, even if it is a not_entrant method. After the
626 // nmethod becomes a zombie, if CompiledMethodUnload event processing
627 // needs to be done, then lock_nmethod() is used directly to keep the
628 // generated code from being reused too early.
629 class nmethodLocker : public StackObj {
630   CompiledMethod* _nm;
631 
632  public:
633 
634   // note: nm can be NULL
635   // Only JvmtiDeferredEvent::compiled_method_unload_event()
636   // should pass zombie_ok == true.
637   static void lock_nmethod(CompiledMethod* nm, bool zombie_ok = false);
638   static void unlock_nmethod(CompiledMethod* nm); // (ditto)
639 
640   nmethodLocker(address pc); // derive nm from pc
641   nmethodLocker(nmethod *nm) { _nm = nm; lock_nmethod(_nm); }
642   nmethodLocker(CompiledMethod *nm) {
643     _nm = nm;
644     lock(_nm);
645   }
646 
647   static void lock(CompiledMethod* method) {
648     if (method == NULL) return;
649     lock_nmethod(method);
650   }
651 
652   static void unlock(CompiledMethod* method) {
653     if (method == NULL) return;
654     unlock_nmethod(method);
655   }
656 
657   nmethodLocker() { _nm = NULL; }
658   ~nmethodLocker() {
659     unlock(_nm);
660   }
661 
662   CompiledMethod* code() { return _nm; }
663   void set_code(CompiledMethod* new_nm) {
664     unlock(_nm);   // note:  This works even if _nm==new_nm.
665     _nm = new_nm;
666     lock(_nm);
667   }
668 };
669 
670 #endif // SHARE_VM_CODE_NMETHOD_HPP