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