1 /*
   2  * Copyright (c) 1997, 2011, 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/codeBlob.hpp"
  29 #include "code/pcDesc.hpp"
  30 
  31 // This class is used internally by nmethods, to cache
  32 // exception/pc/handler information.
  33 
  34 class ExceptionCache : public CHeapObj {
  35   friend class VMStructs;
  36  private:
  37   enum { cache_size = 16 };
  38   klassOop _exception_type;
  39   address  _pc[cache_size];
  40   address  _handler[cache_size];
  41   int      _count;
  42   ExceptionCache* _next;
  43 
  44   address pc_at(int index)                     { assert(index >= 0 && index < count(),""); return _pc[index]; }
  45   void    set_pc_at(int index, address a)      { assert(index >= 0 && index < cache_size,""); _pc[index] = a; }
  46   address handler_at(int index)                { assert(index >= 0 && index < count(),""); return _handler[index]; }
  47   void    set_handler_at(int index, address a) { assert(index >= 0 && index < cache_size,""); _handler[index] = a; }
  48   int     count()                              { return _count; }
  49   void    increment_count()                    { _count++; }
  50 
  51  public:
  52 
  53   ExceptionCache(Handle exception, address pc, address handler);
  54 
  55   klassOop  exception_type()                { return _exception_type; }
  56   klassOop* exception_type_addr()           { return &_exception_type; }
  57   ExceptionCache* next()                    { return _next; }
  58   void      set_next(ExceptionCache *ec)    { _next = ec; }
  59 
  60   address match(Handle exception, address pc);
  61   bool    match_exception_with_space(Handle exception) ;
  62   address test_address(address addr);
  63   bool    add_address_and_handler(address addr, address handler) ;
  64 };
  65 
  66 
  67 // cache pc descs found in earlier inquiries
  68 class PcDescCache VALUE_OBJ_CLASS_SPEC {
  69   friend class VMStructs;
  70  private:
  71   enum { cache_size = 4 };
  72   PcDesc* _last_pc_desc;         // most recent pc_desc found
  73   PcDesc* _pc_descs[cache_size]; // last cache_size pc_descs found
  74  public:
  75   PcDescCache() { debug_only(_last_pc_desc = NULL); }
  76   void    reset_to(PcDesc* initial_pc_desc);
  77   PcDesc* find_pc_desc(int pc_offset, bool approximate);
  78   void    add_pc_desc(PcDesc* pc_desc);
  79   PcDesc* last_pc_desc() { return _last_pc_desc; }
  80 };
  81 
  82 
  83 // nmethods (native methods) are the compiled code versions of Java methods.
  84 //
  85 // An nmethod contains:
  86 //  - header                 (the nmethod structure)
  87 //  [Relocation]
  88 //  - relocation information
  89 //  - constant part          (doubles, longs and floats used in nmethod)
  90 //  - oop table
  91 //  [Code]
  92 //  - code body
  93 //  - exception handler
  94 //  - stub code
  95 //  [Debugging information]
  96 //  - oop array
  97 //  - data array
  98 //  - pcs
  99 //  [Exception handler table]
 100 //  - handler entry point array
 101 //  [Implicit Null Pointer exception table]
 102 //  - implicit null table array
 103 
 104 class Dependencies;
 105 class ExceptionHandlerTable;
 106 class ImplicitExceptionTable;
 107 class AbstractCompiler;
 108 class xmlStream;
 109 
 110 class nmethod : public CodeBlob {
 111   friend class VMStructs;
 112   friend class NMethodSweeper;
 113   friend class CodeCache;  // non-perm oops
 114  private:
 115   // Shared fields for all nmethod's
 116   methodOop _method;
 117   int       _entry_bci;        // != InvocationEntryBci if this nmethod is an on-stack replacement method
 118   jmethodID _jmethod_id;       // Cache of method()->jmethod_id()
 119 
 120   // To support simple linked-list chaining of nmethods:
 121   nmethod*  _osr_link;         // from instanceKlass::osr_nmethods_head
 122   nmethod*  _scavenge_root_link; // from CodeCache::scavenge_root_nmethods
 123   nmethod*  _saved_nmethod_link; // from CodeCache::speculatively_disconnect
 124 
 125   static nmethod* volatile _oops_do_mark_nmethods;
 126   nmethod*        volatile _oops_do_mark_link;
 127 
 128   AbstractCompiler* _compiler; // The compiler which compiled this nmethod
 129 
 130   // offsets for entry points
 131   address _entry_point;                      // entry point with class check
 132   address _verified_entry_point;             // entry point without class check
 133   address _osr_entry_point;                  // entry point for on stack replacement
 134 
 135   // Offsets for different nmethod parts
 136   int _exception_offset;
 137   // All deoptee's will resume execution at this location described by
 138   // this offset.
 139   int _deoptimize_offset;
 140   // All deoptee's at a MethodHandle call site will resume execution
 141   // at this location described by this offset.
 142   int _deoptimize_mh_offset;
 143   // Offset of the unwind handler if it exists
 144   int _unwind_handler_offset;
 145 
 146 #ifdef HAVE_DTRACE_H
 147   int _trap_offset;
 148 #endif // def HAVE_DTRACE_H
 149   int _consts_offset;
 150   int _stub_offset;
 151   int _oops_offset;                       // offset to where embedded oop table begins (inside data)
 152   int _scopes_data_offset;
 153   int _scopes_pcs_offset;
 154   int _dependencies_offset;
 155   int _handler_table_offset;
 156   int _nul_chk_table_offset;
 157   int _nmethod_end_offset;
 158 
 159   // location in frame (offset for sp) that deopt can store the original
 160   // pc during a deopt.
 161   int _orig_pc_offset;
 162 
 163   int _compile_id;                           // which compilation made this nmethod
 164   int _comp_level;                           // compilation level
 165 
 166   // protected by CodeCache_lock
 167   bool _has_flushed_dependencies;            // Used for maintenance of dependencies (CodeCache_lock)
 168   bool _speculatively_disconnected;          // Marked for potential unload
 169 
 170   bool _marked_for_reclamation;              // Used by NMethodSweeper (set only by sweeper)
 171   bool _marked_for_deoptimization;           // Used for stack deoptimization
 172 
 173   // used by jvmti to track if an unload event has been posted for this nmethod.
 174   bool _unload_reported;
 175 
 176   // set during construction
 177   unsigned int _has_unsafe_access:1;         // May fault due to unsafe access.
 178   unsigned int _has_method_handle_invokes:1; // Has this method MethodHandle invokes?
 179 
 180   // Protected by Patching_lock
 181   unsigned char _state;                      // {alive, not_entrant, zombie, unloaded)
 182 
 183 #ifdef ASSERT
 184   bool _oops_are_stale;  // indicates that it's no longer safe to access oops section
 185 #endif
 186 
 187   enum { alive        = 0,
 188          not_entrant  = 1, // uncommon trap has happened but activations may still exist
 189          zombie       = 2,
 190          unloaded     = 3 };
 191 
 192 
 193   jbyte _scavenge_root_state;
 194 
 195   NOT_PRODUCT(bool _has_debug_info; )
 196 
 197   // Nmethod Flushing lock. If non-zero, then the nmethod is not removed
 198   // and is not made into a zombie. However, once the nmethod is made into
 199   // a zombie, it will be locked one final time if CompiledMethodUnload
 200   // event processing needs to be done.
 201   jint  _lock_count;
 202 
 203   // not_entrant method removal. Each mark_sweep pass will update
 204   // this mark to current sweep invocation count if it is seen on the
 205   // stack.  An not_entrant method can be removed when there is no
 206   // more activations, i.e., when the _stack_traversal_mark is less than
 207   // current sweep traversal index.
 208   long _stack_traversal_mark;
 209 
 210   ExceptionCache *_exception_cache;
 211   PcDescCache     _pc_desc_cache;
 212 
 213   // These are used for compiled synchronized native methods to
 214   // locate the owner and stack slot for the BasicLock so that we can
 215   // properly revoke the bias of the owner if necessary. They are
 216   // needed because there is no debug information for compiled native
 217   // wrappers and the oop maps are insufficient to allow
 218   // frame::retrieve_receiver() to work. Currently they are expected
 219   // to be byte offsets from the Java stack pointer for maximum code
 220   // sharing between platforms. Note that currently biased locking
 221   // will never cause Class instances to be biased but this code
 222   // handles the static synchronized case as well.
 223   // JVMTI's GetLocalInstance() also uses these offsets to find the receiver
 224   // for non-static native wrapper frames.
 225   ByteSize _native_receiver_sp_offset;
 226   ByteSize _native_basic_lock_sp_offset;
 227 
 228   friend class nmethodLocker;
 229 
 230   // For native wrappers
 231   nmethod(methodOop method,
 232           int nmethod_size,
 233           CodeOffsets* offsets,
 234           CodeBuffer *code_buffer,
 235           int frame_size,
 236           ByteSize basic_lock_owner_sp_offset, /* synchronized natives only */
 237           ByteSize basic_lock_sp_offset,       /* synchronized natives only */
 238           OopMapSet* oop_maps);
 239 
 240 #ifdef HAVE_DTRACE_H
 241   // For native wrappers
 242   nmethod(methodOop method,
 243           int nmethod_size,
 244           CodeOffsets* offsets,
 245           CodeBuffer *code_buffer,
 246           int frame_size);
 247 #endif // def HAVE_DTRACE_H
 248 
 249   // Creation support
 250   nmethod(methodOop method,
 251           int nmethod_size,
 252           int compile_id,
 253           int entry_bci,
 254           CodeOffsets* offsets,
 255           int orig_pc_offset,
 256           DebugInformationRecorder *recorder,
 257           Dependencies* dependencies,
 258           CodeBuffer *code_buffer,
 259           int frame_size,
 260           OopMapSet* oop_maps,
 261           ExceptionHandlerTable* handler_table,
 262           ImplicitExceptionTable* nul_chk_table,
 263           AbstractCompiler* compiler,
 264           int comp_level);
 265 
 266   // helper methods
 267   void* operator new(size_t size, int nmethod_size);
 268 
 269   const char* reloc_string_for(u_char* begin, u_char* end);
 270   // Returns true if this thread changed the state of the nmethod or
 271   // false if another thread performed the transition.
 272   bool make_not_entrant_or_zombie(unsigned int state);
 273   void inc_decompile_count();
 274 
 275   // Used to manipulate the exception cache
 276   void add_exception_cache_entry(ExceptionCache* new_entry);
 277   ExceptionCache* exception_cache_entry_for_exception(Handle exception);
 278 
 279   // Inform external interfaces that a compiled method has been unloaded
 280   void post_compiled_method_unload();
 281 
 282   // Initailize fields to their default values
 283   void init_defaults();
 284 
 285  public:
 286   // create nmethod with entry_bci
 287   static nmethod* new_nmethod(methodHandle method,
 288                               int compile_id,
 289                               int entry_bci,
 290                               CodeOffsets* offsets,
 291                               int orig_pc_offset,
 292                               DebugInformationRecorder* recorder,
 293                               Dependencies* dependencies,
 294                               CodeBuffer *code_buffer,
 295                               int frame_size,
 296                               OopMapSet* oop_maps,
 297                               ExceptionHandlerTable* handler_table,
 298                               ImplicitExceptionTable* nul_chk_table,
 299                               AbstractCompiler* compiler,
 300                               int comp_level);
 301 
 302   static nmethod* new_native_nmethod(methodHandle method,
 303                                      CodeBuffer *code_buffer,
 304                                      int vep_offset,
 305                                      int frame_complete,
 306                                      int frame_size,
 307                                      ByteSize receiver_sp_offset,
 308                                      ByteSize basic_lock_sp_offset,
 309                                      OopMapSet* oop_maps);
 310 
 311 #ifdef HAVE_DTRACE_H
 312   // The method we generate for a dtrace probe has to look
 313   // like an nmethod as far as the rest of the system is concerned
 314   // which is somewhat unfortunate.
 315   static nmethod* new_dtrace_nmethod(methodHandle method,
 316                                      CodeBuffer *code_buffer,
 317                                      int vep_offset,
 318                                      int trap_offset,
 319                                      int frame_complete,
 320                                      int frame_size);
 321 
 322   int trap_offset() const      { return _trap_offset; }
 323   address trap_address() const { return insts_begin() + _trap_offset; }
 324 
 325 #endif // def HAVE_DTRACE_H
 326 
 327   // accessors
 328   methodOop method() const                        { return _method; }
 329   AbstractCompiler* compiler() const              { return _compiler; }
 330 
 331 #ifndef PRODUCT
 332   bool has_debug_info() const                     { return _has_debug_info; }
 333   void set_has_debug_info(bool f)                 { _has_debug_info = false; }
 334 #endif // NOT PRODUCT
 335 
 336   // type info
 337   bool is_nmethod() const                         { return true; }
 338   bool is_java_method() const                     { return !method()->is_native(); }
 339   bool is_native_method() const                   { return method()->is_native(); }
 340   bool is_osr_method() const                      { return _entry_bci != InvocationEntryBci; }
 341 
 342   bool is_compiled_by_c1() const;
 343   bool is_compiled_by_c2() const;
 344   bool is_compiled_by_shark() const;
 345 
 346   // boundaries for different parts
 347   address consts_begin          () const          { return           header_begin() + _consts_offset        ; }
 348   address consts_end            () const          { return           header_begin() +  code_offset()        ; }
 349   address insts_begin           () const          { return           header_begin() +  code_offset()        ; }
 350   address insts_end             () const          { return           header_begin() + _stub_offset          ; }
 351   address stub_begin            () const          { return           header_begin() + _stub_offset          ; }
 352   address stub_end              () const          { return           header_begin() + _oops_offset          ; }
 353   address exception_begin       () const          { return           header_begin() + _exception_offset     ; }
 354   address deopt_handler_begin   () const          { return           header_begin() + _deoptimize_offset    ; }
 355   address deopt_mh_handler_begin() const          { return           header_begin() + _deoptimize_mh_offset ; }
 356   address unwind_handler_begin  () const          { return _unwind_handler_offset != -1 ? (header_begin() + _unwind_handler_offset) : NULL; }
 357   oop*    oops_begin            () const          { return (oop*)   (header_begin() + _oops_offset)         ; }
 358   oop*    oops_end              () const          { return (oop*)   (header_begin() + _scopes_data_offset)  ; }
 359 
 360   address scopes_data_begin     () const          { return           header_begin() + _scopes_data_offset   ; }
 361   address scopes_data_end       () const          { return           header_begin() + _scopes_pcs_offset    ; }
 362   PcDesc* scopes_pcs_begin      () const          { return (PcDesc*)(header_begin() + _scopes_pcs_offset   ); }
 363   PcDesc* scopes_pcs_end        () const          { return (PcDesc*)(header_begin() + _dependencies_offset) ; }
 364   address dependencies_begin    () const          { return           header_begin() + _dependencies_offset  ; }
 365   address dependencies_end      () const          { return           header_begin() + _handler_table_offset ; }
 366   address handler_table_begin   () const          { return           header_begin() + _handler_table_offset ; }
 367   address handler_table_end     () const          { return           header_begin() + _nul_chk_table_offset ; }
 368   address nul_chk_table_begin   () const          { return           header_begin() + _nul_chk_table_offset ; }
 369   address nul_chk_table_end     () const          { return           header_begin() + _nmethod_end_offset   ; }
 370 
 371   // Sizes
 372   int consts_size       () const                  { return            consts_end       () -            consts_begin       (); }
 373   int insts_size        () const                  { return            insts_end        () -            insts_begin        (); }
 374   int stub_size         () const                  { return            stub_end         () -            stub_begin         (); }
 375   int oops_size         () const                  { return (address)  oops_end         () - (address)  oops_begin         (); }
 376   int scopes_data_size  () const                  { return            scopes_data_end  () -            scopes_data_begin  (); }
 377   int scopes_pcs_size   () const                  { return (intptr_t) scopes_pcs_end   () - (intptr_t) scopes_pcs_begin   (); }
 378   int dependencies_size () const                  { return            dependencies_end () -            dependencies_begin (); }
 379   int handler_table_size() const                  { return            handler_table_end() -            handler_table_begin(); }
 380   int nul_chk_table_size() const                  { return            nul_chk_table_end() -            nul_chk_table_begin(); }
 381 
 382   int total_size        () const;
 383 
 384   // Containment
 385   bool consts_contains       (address addr) const { return consts_begin       () <= addr && addr < consts_end       (); }
 386   bool insts_contains        (address addr) const { return insts_begin        () <= addr && addr < insts_end        (); }
 387   bool stub_contains         (address addr) const { return stub_begin         () <= addr && addr < stub_end         (); }
 388   bool oops_contains         (oop*    addr) const { return oops_begin         () <= addr && addr < oops_end         (); }
 389   bool scopes_data_contains  (address addr) const { return scopes_data_begin  () <= addr && addr < scopes_data_end  (); }
 390   bool scopes_pcs_contains   (PcDesc* addr) const { return scopes_pcs_begin   () <= addr && addr < scopes_pcs_end   (); }
 391   bool handler_table_contains(address addr) const { return handler_table_begin() <= addr && addr < handler_table_end(); }
 392   bool nul_chk_table_contains(address addr) const { return nul_chk_table_begin() <= addr && addr < nul_chk_table_end(); }
 393 
 394   // entry points
 395   address entry_point() const                     { return _entry_point;             } // normal entry point
 396   address verified_entry_point() const            { return _verified_entry_point;    } // if klass is correct
 397 
 398   // flag accessing and manipulation
 399   bool  is_in_use() const                         { return _state == alive; }
 400   bool  is_alive() const                          { return _state == alive || _state == not_entrant; }
 401   bool  is_not_entrant() const                    { return _state == not_entrant; }
 402   bool  is_zombie() const                         { return _state == zombie; }
 403   bool  is_unloaded() const                       { return _state == unloaded;   }
 404 
 405   // Make the nmethod non entrant. The nmethod will continue to be
 406   // alive.  It is used when an uncommon trap happens.  Returns true
 407   // if this thread changed the state of the nmethod or false if
 408   // another thread performed the transition.
 409   bool  make_not_entrant()                        { return make_not_entrant_or_zombie(not_entrant); }
 410   bool  make_zombie()                             { return make_not_entrant_or_zombie(zombie); }
 411 
 412   // used by jvmti to track if the unload event has been reported
 413   bool  unload_reported()                         { return _unload_reported; }
 414   void  set_unload_reported()                     { _unload_reported = true; }
 415 
 416   bool  is_marked_for_deoptimization() const      { return _marked_for_deoptimization; }
 417   void  mark_for_deoptimization()                 { _marked_for_deoptimization = true; }
 418 
 419   void  make_unloaded(BoolObjectClosure* is_alive, oop cause);
 420 
 421   bool has_dependencies()                         { return dependencies_size() != 0; }
 422   void flush_dependencies(BoolObjectClosure* is_alive);
 423   bool has_flushed_dependencies()                 { return _has_flushed_dependencies; }
 424   void set_has_flushed_dependencies()             {
 425     assert(!has_flushed_dependencies(), "should only happen once");
 426     _has_flushed_dependencies = 1;
 427   }
 428 
 429   bool  is_marked_for_reclamation() const         { return _marked_for_reclamation; }
 430   void  mark_for_reclamation()                    { _marked_for_reclamation = 1; }
 431 
 432   bool  has_unsafe_access() const                 { return _has_unsafe_access; }
 433   void  set_has_unsafe_access(bool z)             { _has_unsafe_access = z; }
 434 
 435   bool  has_method_handle_invokes() const         { return _has_method_handle_invokes; }
 436   void  set_has_method_handle_invokes(bool z)     { _has_method_handle_invokes = z; }
 437 
 438   bool  is_speculatively_disconnected() const     { return _speculatively_disconnected; }
 439   void  set_speculatively_disconnected(bool z)     { _speculatively_disconnected = z; }
 440 
 441   int   comp_level() const                        { return _comp_level; }
 442 
 443   // Support for oops in scopes and relocs:
 444   // Note: index 0 is reserved for null.
 445   oop   oop_at(int index) const                   { return index == 0 ? (oop) NULL: *oop_addr_at(index); }
 446   oop*  oop_addr_at(int index) const {  // for GC
 447     // relocation indexes are biased by 1 (because 0 is reserved)
 448     assert(index > 0 && index <= oops_size(), "must be a valid non-zero index");
 449     assert(!_oops_are_stale, "oops are stale");
 450     return &oops_begin()[index - 1];
 451   }
 452 
 453   void copy_oops(GrowableArray<jobject>* oops);
 454 
 455   // Relocation support
 456 private:
 457   void fix_oop_relocations(address begin, address end, bool initialize_immediates);
 458   inline void initialize_immediate_oop(oop* dest, jobject handle);
 459 
 460 public:
 461   void fix_oop_relocations(address begin, address end) { fix_oop_relocations(begin, end, false); }
 462   void fix_oop_relocations()                           { fix_oop_relocations(NULL, NULL, false); }
 463 
 464   bool is_at_poll_return(address pc);
 465   bool is_at_poll_or_poll_return(address pc);
 466 
 467   // Non-perm oop support
 468   bool  on_scavenge_root_list() const                  { return (_scavenge_root_state & 1) != 0; }
 469  protected:
 470   enum { npl_on_list = 0x01, npl_marked = 0x10 };
 471   void  set_on_scavenge_root_list()                    { _scavenge_root_state = npl_on_list; }
 472   void  clear_on_scavenge_root_list()                  { _scavenge_root_state = 0; }
 473   // assertion-checking and pruning logic uses the bits of _scavenge_root_state
 474 #ifndef PRODUCT
 475   void  set_scavenge_root_marked()                     { _scavenge_root_state |= npl_marked; }
 476   void  clear_scavenge_root_marked()                   { _scavenge_root_state &= ~npl_marked; }
 477   bool  scavenge_root_not_marked()                     { return (_scavenge_root_state &~ npl_on_list) == 0; }
 478   // N.B. there is no positive marked query, and we only use the not_marked query for asserts.
 479 #endif //PRODUCT
 480   nmethod* scavenge_root_link() const                  { return _scavenge_root_link; }
 481   void     set_scavenge_root_link(nmethod *n)          { _scavenge_root_link = n; }
 482 
 483   nmethod* saved_nmethod_link() const                  { return _saved_nmethod_link; }
 484   void     set_saved_nmethod_link(nmethod *n)          { _saved_nmethod_link = n; }
 485 
 486  public:
 487 
 488   // Sweeper support
 489   long  stack_traversal_mark()                    { return _stack_traversal_mark; }
 490   void  set_stack_traversal_mark(long l)          { _stack_traversal_mark = l; }
 491 
 492   // Exception cache support
 493   ExceptionCache* exception_cache() const         { return _exception_cache; }
 494   void set_exception_cache(ExceptionCache *ec)    { _exception_cache = ec; }
 495   address handler_for_exception_and_pc(Handle exception, address pc);
 496   void add_handler_for_exception_and_pc(Handle exception, address pc, address handler);
 497   void remove_from_exception_cache(ExceptionCache* ec);
 498 
 499   // implicit exceptions support
 500   address continuation_for_implicit_exception(address pc);
 501 
 502   // On-stack replacement support
 503   int   osr_entry_bci() const                     { assert(_entry_bci != InvocationEntryBci, "wrong kind of nmethod"); return _entry_bci; }
 504   address  osr_entry() const                      { assert(_entry_bci != InvocationEntryBci, "wrong kind of nmethod"); return _osr_entry_point; }
 505   void  invalidate_osr_method();
 506   nmethod* osr_link() const                       { return _osr_link; }
 507   void     set_osr_link(nmethod *n)               { _osr_link = n; }
 508 
 509   // tells whether frames described by this nmethod can be deoptimized
 510   // note: native wrappers cannot be deoptimized.
 511   bool can_be_deoptimized() const { return is_java_method(); }
 512 
 513   // Inline cache support
 514   void clear_inline_caches();
 515   void cleanup_inline_caches();
 516   bool inlinecache_check_contains(address addr) const {
 517     return (addr >= code_begin() && addr < verified_entry_point());
 518   }
 519 
 520   // unlink and deallocate this nmethod
 521   // Only NMethodSweeper class is expected to use this. NMethodSweeper is not
 522   // expected to use any other private methods/data in this class.
 523 
 524  protected:
 525   void flush();
 526 
 527  public:
 528   // When true is returned, it is unsafe to remove this nmethod even if
 529   // it is a zombie, since the VM or the ServiceThread might still be
 530   // using it. Should only be called from a safepoint.
 531   bool is_locked_by_vm() const                    { return _lock_count >0; }
 532 
 533   // See comment at definition of _last_seen_on_stack
 534   void mark_as_seen_on_stack();
 535   bool can_not_entrant_be_converted();
 536 
 537   // Evolution support. We make old (discarded) compiled methods point to new methodOops.
 538   void set_method(methodOop method) { _method = method; }
 539 
 540   // GC support
 541   void do_unloading(BoolObjectClosure* is_alive, OopClosure* keep_alive,
 542                     bool unloading_occurred);
 543   bool can_unload(BoolObjectClosure* is_alive, OopClosure* keep_alive,
 544                   oop* root, bool unloading_occurred);
 545 
 546   void preserve_callee_argument_oops(frame fr, const RegisterMap *reg_map,
 547                                      OopClosure* f);
 548   void oops_do(OopClosure* f) { oops_do(f, false); }
 549   void oops_do(OopClosure* f, bool do_strong_roots_only);
 550   bool detect_scavenge_root_oops();
 551   void verify_scavenge_root_oops() PRODUCT_RETURN;
 552 
 553   bool test_set_oops_do_mark();
 554   static void oops_do_marking_prologue();
 555   static void oops_do_marking_epilogue();
 556   static bool oops_do_marking_is_active() { return _oops_do_mark_nmethods != NULL; }
 557   DEBUG_ONLY(bool test_oops_do_mark() { return _oops_do_mark_link != NULL; })
 558 
 559   // ScopeDesc for an instruction
 560   ScopeDesc* scope_desc_at(address pc);
 561 
 562  private:
 563   ScopeDesc* scope_desc_in(address begin, address end);
 564 
 565   address* orig_pc_addr(const frame* fr) { return (address*) ((address)fr->unextended_sp() + _orig_pc_offset); }
 566 
 567   PcDesc* find_pc_desc_internal(address pc, bool approximate);
 568 
 569   PcDesc* find_pc_desc(address pc, bool approximate) {
 570     PcDesc* desc = _pc_desc_cache.last_pc_desc();
 571     if (desc != NULL && desc->pc_offset() == pc - code_begin()) {
 572       return desc;
 573     }
 574     return find_pc_desc_internal(pc, approximate);
 575   }
 576 
 577  public:
 578   // ScopeDesc retrieval operation
 579   PcDesc* pc_desc_at(address pc)   { return find_pc_desc(pc, false); }
 580   // pc_desc_near returns the first PcDesc at or after the givne pc.
 581   PcDesc* pc_desc_near(address pc) { return find_pc_desc(pc, true); }
 582 
 583  public:
 584   // copying of debugging information
 585   void copy_scopes_pcs(PcDesc* pcs, int count);
 586   void copy_scopes_data(address buffer, int size);
 587 
 588   // Deopt
 589   // Return true is the PC is one would expect if the frame is being deopted.
 590   bool is_deopt_pc      (address pc) { return is_deopt_entry(pc) || is_deopt_mh_entry(pc); }
 591   bool is_deopt_entry   (address pc) { return pc == deopt_handler_begin(); }
 592   bool is_deopt_mh_entry(address pc) { return pc == deopt_mh_handler_begin(); }
 593   // Accessor/mutator for the original pc of a frame before a frame was deopted.
 594   address get_original_pc(const frame* fr) { return *orig_pc_addr(fr); }
 595   void    set_original_pc(const frame* fr, address pc) { *orig_pc_addr(fr) = pc; }
 596 
 597   static address get_deopt_original_pc(const frame* fr);
 598 
 599   // MethodHandle
 600   bool is_method_handle_return(address return_pc);
 601 
 602   // jvmti support:
 603   void post_compiled_method_load_event();
 604   jmethodID get_and_cache_jmethod_id();
 605 
 606   // verify operations
 607   void verify();
 608   void verify_scopes();
 609   void verify_interrupt_point(address interrupt_point);
 610 
 611   // print compilation helper
 612   static void print_compilation(outputStream *st, const char *method_name, const char *title,
 613                                 methodOop method, bool is_blocking, int compile_id, int bci, int comp_level);
 614 
 615   // printing support
 616   void print()                          const;
 617   void print_code();
 618   void print_relocations()                        PRODUCT_RETURN;
 619   void print_pcs()                                PRODUCT_RETURN;
 620   void print_scopes()                             PRODUCT_RETURN;
 621   void print_dependencies()                       PRODUCT_RETURN;
 622   void print_value_on(outputStream* st) const     PRODUCT_RETURN;
 623   void print_calls(outputStream* st)              PRODUCT_RETURN;
 624   void print_handler_table()                      PRODUCT_RETURN;
 625   void print_nul_chk_table()                      PRODUCT_RETURN;
 626   void print_nmethod(bool print_code);
 627 
 628   // need to re-define this from CodeBlob else the overload hides it
 629   virtual void print_on(outputStream* st) const { CodeBlob::print_on(st); }
 630   void print_on(outputStream* st, const char* title) const;
 631 
 632   // Logging
 633   void log_identity(xmlStream* log) const;
 634   void log_new_nmethod() const;
 635   void log_state_change() const;
 636 
 637   // Prints block-level comments, including nmethod specific block labels:
 638   virtual void print_block_comment(outputStream* stream, address block_begin) {
 639     print_nmethod_labels(stream, block_begin);
 640     CodeBlob::print_block_comment(stream, block_begin);
 641   }
 642   void print_nmethod_labels(outputStream* stream, address block_begin);
 643 
 644   // Prints a comment for one native instruction (reloc info, pc desc)
 645   void print_code_comment_on(outputStream* st, int column, address begin, address end);
 646   static void print_statistics()                  PRODUCT_RETURN;
 647 
 648   // Compiler task identification.  Note that all OSR methods
 649   // are numbered in an independent sequence if CICountOSR is true,
 650   // and native method wrappers are also numbered independently if
 651   // CICountNative is true.
 652   int  compile_id() const                         { return _compile_id; }
 653   const char* compile_kind() const;
 654 
 655   // For debugging
 656   // CompiledIC*    IC_at(char* p) const;
 657   // PrimitiveIC*   primitiveIC_at(char* p) const;
 658   oop embeddedOop_at(address p);
 659 
 660   // tells if any of this method's dependencies have been invalidated
 661   // (this is expensive!)
 662   bool check_all_dependencies();
 663 
 664   // tells if this compiled method is dependent on the given changes,
 665   // and the changes have invalidated it
 666   bool check_dependency_on(DepChange& changes);
 667 
 668   // Evolution support. Tells if this compiled method is dependent on any of
 669   // methods m() of class dependee, such that if m() in dependee is replaced,
 670   // this compiled method will have to be deoptimized.
 671   bool is_evol_dependent_on(klassOop dependee);
 672 
 673   // Fast breakpoint support. Tells if this compiled method is
 674   // dependent on the given method. Returns true if this nmethod
 675   // corresponds to the given method as well.
 676   bool is_dependent_on_method(methodOop dependee);
 677 
 678   // is it ok to patch at address?
 679   bool is_patchable_at(address instr_address);
 680 
 681   // UseBiasedLocking support
 682   ByteSize native_receiver_sp_offset() {
 683     return _native_receiver_sp_offset;
 684   }
 685   ByteSize native_basic_lock_sp_offset() {
 686     return _native_basic_lock_sp_offset;
 687   }
 688 
 689   // support for code generation
 690   static int verified_entry_point_offset()        { return offset_of(nmethod, _verified_entry_point); }
 691   static int osr_entry_point_offset()             { return offset_of(nmethod, _osr_entry_point); }
 692   static int entry_bci_offset()                   { return offset_of(nmethod, _entry_bci); }
 693 
 694 };
 695 
 696 // Locks an nmethod so its code will not get removed and it will not
 697 // be made into a zombie, even if it is a not_entrant method. After the
 698 // nmethod becomes a zombie, if CompiledMethodUnload event processing
 699 // needs to be done, then lock_nmethod() is used directly to keep the
 700 // generated code from being reused too early.
 701 class nmethodLocker : public StackObj {
 702   nmethod* _nm;
 703 
 704  public:
 705 
 706   // note: nm can be NULL
 707   // Only JvmtiDeferredEvent::compiled_method_unload_event()
 708   // should pass zombie_ok == true.
 709   static void lock_nmethod(nmethod* nm, bool zombie_ok = false);
 710   static void unlock_nmethod(nmethod* nm); // (ditto)
 711 
 712   nmethodLocker(address pc); // derive nm from pc
 713   nmethodLocker(nmethod *nm) { _nm = nm; lock_nmethod(_nm); }
 714   nmethodLocker() { _nm = NULL; }
 715   ~nmethodLocker() { unlock_nmethod(_nm); }
 716 
 717   nmethod* code() { return _nm; }
 718   void set_code(nmethod* new_nm) {
 719     unlock_nmethod(_nm);   // note:  This works even if _nm==new_nm.
 720     _nm = new_nm;
 721     lock_nmethod(_nm);
 722   }
 723 };
 724 
 725 #endif // SHARE_VM_CODE_NMETHOD_HPP