1 /*
   2  * Copyright (c) 1997, 2017, 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_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   // offsets for entry points
  78   address _entry_point;                      // entry point with class check
  79   address _verified_entry_point;             // entry point without class check
  80   address _osr_entry_point;                  // entry point for on stack replacement
  81 
  82   // Offsets for different nmethod parts
  83   int  _exception_offset;
  84   // Offset of the unwind handler if it exists
  85   int _unwind_handler_offset;
  86 
  87   int _consts_offset;
  88   int _stub_offset;
  89   int _oops_offset;                       // offset to where embedded oop table begins (inside data)
  90   int _metadata_offset;                   // embedded meta data table
  91   int _scopes_data_offset;
  92   int _scopes_pcs_offset;
  93   int _dependencies_offset;
  94   int _handler_table_offset;
  95   int _nul_chk_table_offset;
  96   int _nmethod_end_offset;
  97 
  98   int code_offset() const { return (address) code_begin() - header_begin(); }
  99 
 100   // location in frame (offset for sp) that deopt can store the original
 101   // pc during a deopt.
 102   int _orig_pc_offset;
 103 
 104   int _compile_id;                           // which compilation made this nmethod
 105   int _comp_level;                           // compilation level
 106 
 107   // protected by CodeCache_lock
 108   bool _has_flushed_dependencies;            // Used for maintenance of dependencies (CodeCache_lock)
 109 
 110   // used by jvmti to track if an unload event has been posted for this nmethod.
 111   bool _unload_reported;
 112 
 113   // Protected by Patching_lock
 114   volatile unsigned char _state;             // {in_use, not_entrant, zombie, unloaded}
 115 
 116 #ifdef ASSERT
 117   bool _oops_are_stale;  // indicates that it's no longer safe to access oops section
 118 #endif
 119 
 120   jbyte _scavenge_root_state;
 121 
 122 #if INCLUDE_RTM_OPT
 123   // RTM state at compile time. Used during deoptimization to decide
 124   // whether to restart collecting RTM locking abort statistic again.
 125   RTMState _rtm_state;
 126 #endif
 127 
 128   // Nmethod Flushing lock. If non-zero, then the nmethod is not removed
 129   // and is not made into a zombie. However, once the nmethod is made into
 130   // a zombie, it will be locked one final time if CompiledMethodUnload
 131   // event processing needs to be done.
 132   volatile jint _lock_count;
 133 
 134   // not_entrant method removal. Each mark_sweep pass will update
 135   // this mark to current sweep invocation count if it is seen on the
 136   // stack.  An not_entrant method can be removed when there are no
 137   // more activations, i.e., when the _stack_traversal_mark is less than
 138   // current sweep traversal index.
 139   volatile long _stack_traversal_mark;
 140 
 141   // The _hotness_counter indicates the hotness of a method. The higher
 142   // the value the hotter the method. The hotness counter of a nmethod is
 143   // set to [(ReservedCodeCacheSize / (1024 * 1024)) * 2] each time the method
 144   // is active while stack scanning (mark_active_nmethods()). The hotness
 145   // counter is decreased (by 1) while sweeping.
 146   int _hotness_counter;
 147 
 148   // These are used for compiled synchronized native methods to
 149   // locate the owner and stack slot for the BasicLock so that we can
 150   // properly revoke the bias of the owner if necessary. They are
 151   // needed because there is no debug information for compiled native
 152   // wrappers and the oop maps are insufficient to allow
 153   // frame::retrieve_receiver() to work. Currently they are expected
 154   // to be byte offsets from the Java stack pointer for maximum code
 155   // sharing between platforms. Note that currently biased locking
 156   // will never cause Class instances to be biased but this code
 157   // handles the static synchronized case as well.
 158   // JVMTI's GetLocalInstance() also uses these offsets to find the receiver
 159   // for non-static native wrapper frames.
 160   ByteSize _native_receiver_sp_offset;
 161   ByteSize _native_basic_lock_sp_offset;
 162 
 163   friend class nmethodLocker;
 164 
 165   // For native wrappers
 166   nmethod(Method* method,
 167           CompilerType type,
 168           int nmethod_size,
 169           int compile_id,
 170           CodeOffsets* offsets,
 171           CodeBuffer *code_buffer,
 172           int frame_size,
 173           ByteSize basic_lock_owner_sp_offset, /* synchronized natives only */
 174           ByteSize basic_lock_sp_offset,       /* synchronized natives only */
 175           OopMapSet* oop_maps);
 176 
 177   // Creation support
 178   nmethod(Method* method,
 179           CompilerType type,
 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   // type info
 255   bool is_nmethod() const                         { return true; }
 256   bool is_osr_method() const                      { return _entry_bci != InvocationEntryBci; }
 257 
 258   // boundaries for different parts
 259   address consts_begin          () const          { return           header_begin() + _consts_offset        ; }
 260   address consts_end            () const          { return           code_begin()                           ; }
 261   address stub_begin            () const          { return           header_begin() + _stub_offset          ; }
 262   address stub_end              () const          { return           header_begin() + _oops_offset          ; }
 263   address exception_begin       () const          { return           header_begin() + _exception_offset     ; }
 264   address unwind_handler_begin  () const          { return _unwind_handler_offset != -1 ? (header_begin() + _unwind_handler_offset) : NULL; }
 265   oop*    oops_begin            () const          { return (oop*)   (header_begin() + _oops_offset)         ; }
 266   oop*    oops_end              () const          { return (oop*)   (header_begin() + _metadata_offset)     ; }
 267 
 268   Metadata** metadata_begin   () const            { return (Metadata**)  (header_begin() + _metadata_offset)     ; }
 269   Metadata** metadata_end     () const            { return (Metadata**)  _scopes_data_begin; }
 270 
 271   address scopes_data_end       () const          { return           header_begin() + _scopes_pcs_offset    ; }
 272   PcDesc* scopes_pcs_begin      () const          { return (PcDesc*)(header_begin() + _scopes_pcs_offset   ); }
 273   PcDesc* scopes_pcs_end        () const          { return (PcDesc*)(header_begin() + _dependencies_offset) ; }
 274   address dependencies_begin    () const          { return           header_begin() + _dependencies_offset  ; }
 275   address dependencies_end      () const          { return           header_begin() + _handler_table_offset ; }
 276   address handler_table_begin   () const          { return           header_begin() + _handler_table_offset ; }
 277   address handler_table_end     () const          { return           header_begin() + _nul_chk_table_offset ; }
 278   address nul_chk_table_begin   () const          { return           header_begin() + _nul_chk_table_offset ; }
 279   address nul_chk_table_end     () const          { return           header_begin() + _nmethod_end_offset   ; }
 280 
 281   // Sizes
 282   int oops_size         () const                  { return (address)  oops_end         () - (address)  oops_begin         (); }
 283   int metadata_size     () const                  { return (address)  metadata_end     () - (address)  metadata_begin     (); }
 284   int dependencies_size () const                  { return            dependencies_end () -            dependencies_begin (); }
 285 
 286   int     oops_count() const { assert(oops_size() % oopSize == 0, "");  return (oops_size() / oopSize) + 1; }
 287   int metadata_count() const { assert(metadata_size() % wordSize == 0, ""); return (metadata_size() / wordSize) + 1; }
 288 
 289   int total_size        () const;
 290 
 291   void dec_hotness_counter()        { _hotness_counter--; }
 292   void set_hotness_counter(int val) { _hotness_counter = val; }
 293   int  hotness_counter() const      { return _hotness_counter; }
 294 
 295   // Containment
 296   bool oops_contains         (oop*    addr) const { return oops_begin         () <= addr && addr < oops_end         (); }
 297   bool metadata_contains     (Metadata** addr) const   { return metadata_begin     () <= addr && addr < metadata_end     (); }
 298   bool scopes_data_contains  (address addr) const { return scopes_data_begin  () <= addr && addr < scopes_data_end  (); }
 299   bool scopes_pcs_contains   (PcDesc* addr) const { return scopes_pcs_begin   () <= addr && addr < scopes_pcs_end   (); }
 300 
 301   // entry points
 302   address entry_point() const                     { return _entry_point;             } // normal entry point
 303   address verified_entry_point() const            { return _verified_entry_point;    } // if klass is correct
 304 
 305   // flag accessing and manipulation
 306   bool  is_in_use() const                         { return _state == in_use; }
 307   bool  is_alive() const                          { unsigned char s = _state; return s < zombie; }
 308   bool  is_not_entrant() const                    { return _state == not_entrant; }
 309   bool  is_zombie() const                         { return _state == zombie; }
 310   bool  is_unloaded() const                       { return _state == unloaded; }
 311 
 312 #if INCLUDE_RTM_OPT
 313   // rtm state accessing and manipulating
 314   RTMState  rtm_state() const                     { return _rtm_state; }
 315   void set_rtm_state(RTMState state)              { _rtm_state = state; }
 316 #endif
 317 
 318   // Make the nmethod non entrant. The nmethod will continue to be
 319   // alive.  It is used when an uncommon trap happens.  Returns true
 320   // if this thread changed the state of the nmethod or false if
 321   // another thread performed the transition.
 322   bool  make_not_entrant() {
 323     assert(!method()->is_method_handle_intrinsic(), "Cannot make MH intrinsic not entrant");
 324     return make_not_entrant_or_zombie(not_entrant);
 325   }
 326   bool  make_not_used()    { return make_not_entrant(); }
 327   bool  make_zombie()      { return make_not_entrant_or_zombie(zombie); }
 328 
 329   // used by jvmti to track if the unload event has been reported
 330   bool  unload_reported()                         { return _unload_reported; }
 331   void  set_unload_reported()                     { _unload_reported = true; }
 332 
 333   int get_state() const {
 334     return _state;
 335   }
 336 
 337   void  make_unloaded(BoolObjectClosure* is_alive, oop cause);
 338 
 339   bool has_dependencies()                         { return dependencies_size() != 0; }
 340   void flush_dependencies(BoolObjectClosure* is_alive);
 341   bool has_flushed_dependencies()                 { return _has_flushed_dependencies; }
 342   void set_has_flushed_dependencies()             {
 343     assert(!has_flushed_dependencies(), "should only happen once");
 344     _has_flushed_dependencies = 1;
 345   }
 346 
 347   int   comp_level() const                        { return _comp_level; }
 348 
 349   // Support for oops in scopes and relocs:
 350   // Note: index 0 is reserved for null.
 351   oop   oop_at(int index) const                   { return index == 0 ? (oop) NULL: *oop_addr_at(index); }
 352   oop*  oop_addr_at(int index) const {  // for GC
 353     // relocation indexes are biased by 1 (because 0 is reserved)
 354     assert(index > 0 && index <= oops_count(), "must be a valid non-zero index");
 355     assert(!_oops_are_stale, "oops are stale");
 356     return &oops_begin()[index - 1];
 357   }
 358 
 359   // Support for meta data in scopes and relocs:
 360   // Note: index 0 is reserved for null.
 361   Metadata*     metadata_at(int index) const      { return index == 0 ? NULL: *metadata_addr_at(index); }
 362   Metadata**  metadata_addr_at(int index) const {  // for GC
 363     // relocation indexes are biased by 1 (because 0 is reserved)
 364     assert(index > 0 && index <= metadata_count(), "must be a valid non-zero index");
 365     return &metadata_begin()[index - 1];
 366   }
 367 
 368   void copy_values(GrowableArray<jobject>* oops);
 369   void copy_values(GrowableArray<Metadata*>* metadata);
 370 
 371   // Relocation support
 372 private:
 373   void fix_oop_relocations(address begin, address end, bool initialize_immediates);
 374   inline void initialize_immediate_oop(oop* dest, jobject handle);
 375 
 376 public:
 377   void fix_oop_relocations(address begin, address end) { fix_oop_relocations(begin, end, false); }
 378   void fix_oop_relocations()                           { fix_oop_relocations(NULL, NULL, false); }
 379 
 380   // Scavengable oop support
 381   bool  on_scavenge_root_list() const                  { return (_scavenge_root_state & 1) != 0; }
 382  protected:
 383   enum { sl_on_list = 0x01, sl_marked = 0x10 };
 384   void  set_on_scavenge_root_list()                    { _scavenge_root_state = sl_on_list; }
 385   void  clear_on_scavenge_root_list()                  { _scavenge_root_state = 0; }
 386   // assertion-checking and pruning logic uses the bits of _scavenge_root_state
 387 #ifndef PRODUCT
 388   void  set_scavenge_root_marked()                     { _scavenge_root_state |= sl_marked; }
 389   void  clear_scavenge_root_marked()                   { _scavenge_root_state &= ~sl_marked; }
 390   bool  scavenge_root_not_marked()                     { return (_scavenge_root_state &~ sl_on_list) == 0; }
 391   // N.B. there is no positive marked query, and we only use the not_marked query for asserts.
 392 #endif //PRODUCT
 393   nmethod* scavenge_root_link() const                  { return _scavenge_root_link; }
 394   void     set_scavenge_root_link(nmethod *n)          { _scavenge_root_link = n; }
 395 
 396  public:
 397 
 398   // Sweeper support
 399   long  stack_traversal_mark()                    { return _stack_traversal_mark; }
 400   void  set_stack_traversal_mark(long l)          { _stack_traversal_mark = l; }
 401 
 402   // implicit exceptions support
 403   address continuation_for_implicit_exception(address pc);
 404 
 405   // On-stack replacement support
 406   int   osr_entry_bci() const                     { assert(is_osr_method(), "wrong kind of nmethod"); return _entry_bci; }
 407   address  osr_entry() const                      { assert(is_osr_method(), "wrong kind of nmethod"); return _osr_entry_point; }
 408   void  invalidate_osr_method();
 409   nmethod* osr_link() const                       { return _osr_link; }
 410   void     set_osr_link(nmethod *n)               { _osr_link = n; }
 411 
 412   // Verify calls to dead methods have been cleaned.
 413   void verify_clean_inline_caches();
 414 
 415   // unlink and deallocate this nmethod
 416   // Only NMethodSweeper class is expected to use this. NMethodSweeper is not
 417   // expected to use any other private methods/data in this class.
 418 
 419  protected:
 420   void flush();
 421 
 422  public:
 423   // When true is returned, it is unsafe to remove this nmethod even if
 424   // it is a zombie, since the VM or the ServiceThread might still be
 425   // using it.
 426   bool is_locked_by_vm() const                    { return _lock_count >0; }
 427 
 428   // See comment at definition of _last_seen_on_stack
 429   void mark_as_seen_on_stack();
 430   bool can_convert_to_zombie();
 431 
 432   // Evolution support. We make old (discarded) compiled methods point to new Method*s.
 433   void set_method(Method* method) { _method = method; }
 434 
 435 #if INCLUDE_JVMCI
 436   oop jvmci_installed_code() { return _jvmci_installed_code ; }
 437   char* jvmci_installed_code_name(char* buf, size_t buflen);
 438 
 439   // Update the state of any InstalledCode instance associated with
 440   // this nmethod based on the current value of _state.
 441   void maybe_invalidate_installed_code();
 442 
 443   // Helper function to invalidate InstalledCode instances
 444   static void invalidate_installed_code(Handle installed_code, TRAPS);
 445 
 446   oop speculation_log() { return _speculation_log ; }
 447 
 448  private:
 449   void clear_jvmci_installed_code();
 450 
 451  public:
 452 #endif
 453 
 454  protected:
 455   virtual bool do_unloading_oops(address low_boundary, BoolObjectClosure* is_alive, bool unloading_occurred);
 456 #if INCLUDE_JVMCI
 457   virtual bool do_unloading_jvmci(BoolObjectClosure* is_alive, bool unloading_occurred);
 458 #endif
 459 
 460  private:
 461   bool do_unloading_scopes(BoolObjectClosure* is_alive, bool unloading_occurred);
 462   //  Unload a nmethod if the *root object is dead.
 463   bool can_unload(BoolObjectClosure* is_alive, oop* root, bool unloading_occurred);
 464   bool unload_if_dead_at(RelocIterator *iter_at_oop, BoolObjectClosure* is_alive, bool unloading_occurred);
 465 
 466  public:
 467   void oops_do(OopClosure* f) { oops_do(f, false); }
 468   void oops_do(OopClosure* f, bool allow_zombie);
 469   bool detect_scavenge_root_oops();
 470   void verify_scavenge_root_oops() PRODUCT_RETURN;
 471 
 472   bool test_set_oops_do_mark();
 473   static void oops_do_marking_prologue();
 474   static void oops_do_marking_epilogue();
 475   static bool oops_do_marking_is_active() { return _oops_do_mark_nmethods != NULL; }
 476   bool test_oops_do_mark() { return _oops_do_mark_link != NULL; }
 477 
 478  private:
 479   ScopeDesc* scope_desc_in(address begin, address end);
 480 
 481   address* orig_pc_addr(const frame* fr) { return (address*) ((address)fr->unextended_sp() + _orig_pc_offset); }
 482 
 483  public:
 484   // copying of debugging information
 485   void copy_scopes_pcs(PcDesc* pcs, int count);
 486   void copy_scopes_data(address buffer, int size);
 487 
 488   // Accessor/mutator for the original pc of a frame before a frame was deopted.
 489   address get_original_pc(const frame* fr) { return *orig_pc_addr(fr); }
 490   void    set_original_pc(const frame* fr, address pc) { *orig_pc_addr(fr) = pc; }
 491 
 492   // jvmti support:
 493   void post_compiled_method_load_event();
 494   jmethodID get_and_cache_jmethod_id();
 495 
 496   // verify operations
 497   void verify();
 498   void verify_scopes();
 499   void verify_interrupt_point(address interrupt_point);
 500 
 501   // printing support
 502   void print()                          const;
 503   void print_relocations()                        PRODUCT_RETURN;
 504   void print_pcs()                                PRODUCT_RETURN;
 505   void print_scopes()                             PRODUCT_RETURN;
 506   void print_dependencies()                       PRODUCT_RETURN;
 507   void print_value_on(outputStream* st) const     PRODUCT_RETURN;
 508   void print_calls(outputStream* st)              PRODUCT_RETURN;
 509   void print_handler_table()                      PRODUCT_RETURN;
 510   void print_nul_chk_table()                      PRODUCT_RETURN;
 511   void print_recorded_oops()                      PRODUCT_RETURN;
 512   void print_recorded_metadata()                  PRODUCT_RETURN;
 513 
 514   void maybe_print_nmethod(DirectiveSet* directive);
 515   void print_nmethod(bool print_code);
 516 
 517   // need to re-define this from CodeBlob else the overload hides it
 518   virtual void print_on(outputStream* st) const { CodeBlob::print_on(st); }
 519   void print_on(outputStream* st, const char* msg) const;
 520 
 521   // Logging
 522   void log_identity(xmlStream* log) const;
 523   void log_new_nmethod() const;
 524   void log_state_change() const;
 525 
 526   // Prints block-level comments, including nmethod specific block labels:
 527   virtual void print_block_comment(outputStream* stream, address block_begin) const {
 528     print_nmethod_labels(stream, block_begin);
 529     CodeBlob::print_block_comment(stream, block_begin);
 530   }
 531   void print_nmethod_labels(outputStream* stream, address block_begin) const;
 532 
 533   // Prints a comment for one native instruction (reloc info, pc desc)
 534   void print_code_comment_on(outputStream* st, int column, address begin, address end);
 535   static void print_statistics() PRODUCT_RETURN;
 536 
 537   // Compiler task identification.  Note that all OSR methods
 538   // are numbered in an independent sequence if CICountOSR is true,
 539   // and native method wrappers are also numbered independently if
 540   // CICountNative is true.
 541   virtual int compile_id() const { return _compile_id; }
 542   const char* compile_kind() const;
 543 
 544   // tells if any of this method's dependencies have been invalidated
 545   // (this is expensive!)
 546   static void check_all_dependencies(DepChange& changes);
 547 
 548   // tells if this compiled method is dependent on the given changes,
 549   // and the changes have invalidated it
 550   bool check_dependency_on(DepChange& changes);
 551 
 552   // Evolution support. Tells if this compiled method is dependent on any of
 553   // methods m() of class dependee, such that if m() in dependee is replaced,
 554   // this compiled method will have to be deoptimized.
 555   bool is_evol_dependent_on(Klass* dependee);
 556 
 557   // Fast breakpoint support. Tells if this compiled method is
 558   // dependent on the given method. Returns true if this nmethod
 559   // corresponds to the given method as well.
 560   virtual bool is_dependent_on_method(Method* dependee);
 561 
 562   // is it ok to patch at address?
 563   bool is_patchable_at(address instr_address);
 564 
 565   // UseBiasedLocking support
 566   ByteSize native_receiver_sp_offset() {
 567     return _native_receiver_sp_offset;
 568   }
 569   ByteSize native_basic_lock_sp_offset() {
 570     return _native_basic_lock_sp_offset;
 571   }
 572 
 573   // support for code generation
 574   static int verified_entry_point_offset()        { return offset_of(nmethod, _verified_entry_point); }
 575   static int osr_entry_point_offset()             { return offset_of(nmethod, _osr_entry_point); }
 576   static int state_offset()                       { return offset_of(nmethod, _state); }
 577 
 578   virtual void metadata_do(void f(Metadata*));
 579 
 580   NativeCallWrapper* call_wrapper_at(address call) const;
 581   NativeCallWrapper* call_wrapper_before(address return_pc) const;
 582   address call_instruction_address(address pc) const;
 583 
 584   virtual CompiledStaticCall* compiledStaticCall_at(Relocation* call_site) const;
 585   virtual CompiledStaticCall* compiledStaticCall_at(address addr) const;
 586   virtual CompiledStaticCall* compiledStaticCall_before(address addr) const;
 587 };
 588 
 589 // Locks an nmethod so its code will not get removed and it will not
 590 // be made into a zombie, even if it is a not_entrant method. After the
 591 // nmethod becomes a zombie, if CompiledMethodUnload event processing
 592 // needs to be done, then lock_nmethod() is used directly to keep the
 593 // generated code from being reused too early.
 594 class nmethodLocker : public StackObj {
 595   CompiledMethod* _nm;
 596 
 597  public:
 598 
 599   // note: nm can be NULL
 600   // Only JvmtiDeferredEvent::compiled_method_unload_event()
 601   // should pass zombie_ok == true.
 602   static void lock_nmethod(CompiledMethod* nm, bool zombie_ok = false);
 603   static void unlock_nmethod(CompiledMethod* nm); // (ditto)
 604 
 605   nmethodLocker(address pc); // derive nm from pc
 606   nmethodLocker(nmethod *nm) { _nm = nm; lock_nmethod(_nm); }
 607   nmethodLocker(CompiledMethod *nm) {
 608     _nm = nm;
 609     lock(_nm);
 610   }
 611 
 612   static void lock(CompiledMethod* method) {
 613     if (method == NULL) return;
 614     lock_nmethod(method);
 615   }
 616 
 617   static void unlock(CompiledMethod* method) {
 618     if (method == NULL) return;
 619     unlock_nmethod(method);
 620   }
 621 
 622   nmethodLocker() { _nm = NULL; }
 623   ~nmethodLocker() {
 624     unlock(_nm);
 625   }
 626 
 627   CompiledMethod* code() { return _nm; }
 628   void set_code(CompiledMethod* new_nm) {
 629     unlock(_nm);   // note:  This works even if _nm==new_nm.
 630     _nm = new_nm;
 631     lock(_nm);
 632   }
 633 };
 634 
 635 #endif // SHARE_VM_CODE_NMETHOD_HPP