1 /*
   2  * Copyright (c) 1997, 2012, 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 #include "oops/metadata.hpp"
  31 
  32 // This class is used internally by nmethods, to cache
  33 // exception/pc/handler information.
  34 
  35 class ExceptionCache : public CHeapObj<mtCode> {
  36   friend class VMStructs;
  37  private:
  38   enum { cache_size = 16 };
  39   Klass*   _exception_type;
  40   address  _pc[cache_size];
  41   address  _handler[cache_size];
  42   int      _count;
  43   ExceptionCache* _next;
  44 
  45   address pc_at(int index)                     { assert(index >= 0 && index < count(),""); return _pc[index]; }
  46   void    set_pc_at(int index, address a)      { assert(index >= 0 && index < cache_size,""); _pc[index] = a; }
  47   address handler_at(int index)                { assert(index >= 0 && index < count(),""); return _handler[index]; }
  48   void    set_handler_at(int index, address a) { assert(index >= 0 && index < cache_size,""); _handler[index] = a; }
  49   int     count()                              { return _count; }
  50   void    increment_count()                    { _count++; }
  51 
  52  public:
  53 
  54   ExceptionCache(Handle exception, address pc, address handler);
  55 
  56   Klass*    exception_type()                { 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;  // scavengable oops
 113  private:
 114   // Shared fields for all nmethod's
 115   Method*   _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 _metadata_offset;                   // embedded meta data table
 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   unsigned int _lazy_critical_native:1;      // Lazy JNI critical native
 180   unsigned int _has_wide_vectors:1;          // Preserve wide vectors at safepoints
 181 
 182   // Protected by Patching_lock
 183   unsigned char _state;                      // {alive, not_entrant, zombie, unloaded}
 184 
 185 #ifdef ASSERT
 186   bool _oops_are_stale;  // indicates that it's no longer safe to access oops section
 187 #endif
 188 
 189   enum { alive        = 0,
 190          not_entrant  = 1, // uncommon trap has happened but activations may still exist
 191          zombie       = 2,
 192          unloaded     = 3 };
 193 
 194 
 195   jbyte _scavenge_root_state;
 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(Method* method,
 232           int nmethod_size,
 233           int compile_id,
 234           CodeOffsets* offsets,
 235           CodeBuffer *code_buffer,
 236           int frame_size,
 237           ByteSize basic_lock_owner_sp_offset, /* synchronized natives only */
 238           ByteSize basic_lock_sp_offset,       /* synchronized natives only */
 239           OopMapSet* oop_maps);
 240 
 241 #ifdef HAVE_DTRACE_H
 242   // For native wrappers
 243   nmethod(Method* method,
 244           int nmethod_size,
 245           CodeOffsets* offsets,
 246           CodeBuffer *code_buffer,
 247           int frame_size);
 248 #endif // def HAVE_DTRACE_H
 249 
 250   // Creation support
 251   nmethod(Method* method,
 252           int nmethod_size,
 253           int compile_id,
 254           int entry_bci,
 255           CodeOffsets* offsets,
 256           int orig_pc_offset,
 257           DebugInformationRecorder *recorder,
 258           Dependencies* dependencies,
 259           CodeBuffer *code_buffer,
 260           int frame_size,
 261           OopMapSet* oop_maps,
 262           ExceptionHandlerTable* handler_table,
 263           ImplicitExceptionTable* nul_chk_table,
 264           AbstractCompiler* compiler,
 265           int comp_level);
 266 
 267   // helper methods
 268   void* operator new(size_t size, int nmethod_size);
 269 
 270   const char* reloc_string_for(u_char* begin, u_char* end);
 271   // Returns true if this thread changed the state of the nmethod or
 272   // false if another thread performed the transition.
 273   bool make_not_entrant_or_zombie(unsigned int state);
 274   void inc_decompile_count();
 275 
 276   // Used to manipulate the exception cache
 277   void add_exception_cache_entry(ExceptionCache* new_entry);
 278   ExceptionCache* exception_cache_entry_for_exception(Handle exception);
 279 
 280   // Inform external interfaces that a compiled method has been unloaded
 281   void post_compiled_method_unload();
 282 
 283   // Initailize fields to their default values
 284   void init_defaults();
 285 
 286  public:
 287   // create nmethod with entry_bci
 288   static nmethod* new_nmethod(methodHandle method,
 289                               int compile_id,
 290                               int entry_bci,
 291                               CodeOffsets* offsets,
 292                               int orig_pc_offset,
 293                               DebugInformationRecorder* recorder,
 294                               Dependencies* dependencies,
 295                               CodeBuffer *code_buffer,
 296                               int frame_size,
 297                               OopMapSet* oop_maps,
 298                               ExceptionHandlerTable* handler_table,
 299                               ImplicitExceptionTable* nul_chk_table,
 300                               AbstractCompiler* compiler,
 301                               int comp_level);
 302 
 303   static nmethod* new_native_nmethod(methodHandle method,
 304                                      int compile_id,
 305                                      CodeBuffer *code_buffer,
 306                                      int vep_offset,
 307                                      int frame_complete,
 308                                      int frame_size,
 309                                      ByteSize receiver_sp_offset,
 310                                      ByteSize basic_lock_sp_offset,
 311                                      OopMapSet* oop_maps);
 312 
 313 #ifdef HAVE_DTRACE_H
 314   // The method we generate for a dtrace probe has to look
 315   // like an nmethod as far as the rest of the system is concerned
 316   // which is somewhat unfortunate.
 317   static nmethod* new_dtrace_nmethod(methodHandle method,
 318                                      CodeBuffer *code_buffer,
 319                                      int vep_offset,
 320                                      int trap_offset,
 321                                      int frame_complete,
 322                                      int frame_size);
 323 
 324   int trap_offset() const      { return _trap_offset; }
 325   address trap_address() const { return insts_begin() + _trap_offset; }
 326 
 327 #endif // def HAVE_DTRACE_H
 328 
 329   // accessors
 330   Method* method() const                          { return _method; }
 331   AbstractCompiler* compiler() const              { return _compiler; }
 332 
 333   // type info
 334   bool is_nmethod() const                         { return true; }
 335   bool is_java_method() const                     { return !method()->is_native(); }
 336   bool is_native_method() const                   { return method()->is_native(); }
 337   bool is_osr_method() const                      { return _entry_bci != InvocationEntryBci; }
 338 
 339   bool is_compiled_by_c1() const;
 340   bool is_compiled_by_c2() const;
 341   bool is_compiled_by_shark() const;
 342 
 343   // boundaries for different parts
 344   address consts_begin          () const          { return           header_begin() + _consts_offset        ; }
 345   address consts_end            () const          { return           header_begin() +  code_offset()        ; }
 346   address insts_begin           () const          { return           header_begin() +  code_offset()        ; }
 347   address insts_end             () const          { return           header_begin() + _stub_offset          ; }
 348   address stub_begin            () const          { return           header_begin() + _stub_offset          ; }
 349   address stub_end              () const          { return           header_begin() + _oops_offset          ; }
 350   address exception_begin       () const          { return           header_begin() + _exception_offset     ; }
 351   address deopt_handler_begin   () const          { return           header_begin() + _deoptimize_offset    ; }
 352   address deopt_mh_handler_begin() const          { return           header_begin() + _deoptimize_mh_offset ; }
 353   address unwind_handler_begin  () const          { return _unwind_handler_offset != -1 ? (header_begin() + _unwind_handler_offset) : NULL; }
 354   oop*    oops_begin            () const          { return (oop*)   (header_begin() + _oops_offset)         ; }
 355   oop*    oops_end              () const          { return (oop*)   (header_begin() + _metadata_offset)     ; }
 356 
 357   Metadata** metadata_begin   () const            { return (Metadata**)  (header_begin() + _metadata_offset)     ; }
 358   Metadata** metadata_end     () const            { return (Metadata**)  (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 metadata_size     () const                  { return (address)  metadata_end     () - (address)  metadata_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 metadata_contains     (Metadata** addr) const   { return metadata_begin     () <= addr && addr < metadata_end     (); }
 391   bool scopes_data_contains  (address addr) const { return scopes_data_begin  () <= addr && addr < scopes_data_end  (); }
 392   bool scopes_pcs_contains   (PcDesc* addr) const { return scopes_pcs_begin   () <= addr && addr < scopes_pcs_end   (); }
 393   bool handler_table_contains(address addr) const { return handler_table_begin() <= addr && addr < handler_table_end(); }
 394   bool nul_chk_table_contains(address addr) const { return nul_chk_table_begin() <= addr && addr < nul_chk_table_end(); }
 395 
 396   // entry points
 397   address entry_point() const                     { return _entry_point;             } // normal entry point
 398   address verified_entry_point() const            { return _verified_entry_point;    } // if klass is correct
 399 
 400   // flag accessing and manipulation
 401   bool  is_in_use() const                         { return _state == alive; }
 402   bool  is_alive() const                          { return _state == alive || _state == not_entrant; }
 403   bool  is_not_entrant() const                    { return _state == not_entrant; }
 404   bool  is_zombie() const                         { return _state == zombie; }
 405   bool  is_unloaded() const                       { return _state == unloaded;   }
 406 
 407   // Make the nmethod non entrant. The nmethod will continue to be
 408   // alive.  It is used when an uncommon trap happens.  Returns true
 409   // if this thread changed the state of the nmethod or false if
 410   // another thread performed the transition.
 411   bool  make_not_entrant()                        { return make_not_entrant_or_zombie(not_entrant); }
 412   bool  make_zombie()                             { return make_not_entrant_or_zombie(zombie); }
 413 
 414   // used by jvmti to track if the unload event has been reported
 415   bool  unload_reported()                         { return _unload_reported; }
 416   void  set_unload_reported()                     { _unload_reported = true; }
 417 
 418   bool  is_marked_for_deoptimization() const      { return _marked_for_deoptimization; }
 419   void  mark_for_deoptimization()                 { _marked_for_deoptimization = true; }
 420 
 421   void  make_unloaded(BoolObjectClosure* is_alive, oop cause);
 422 
 423   bool has_dependencies()                         { return dependencies_size() != 0; }
 424   void flush_dependencies(BoolObjectClosure* is_alive);
 425   bool has_flushed_dependencies()                 { return _has_flushed_dependencies; }
 426   void set_has_flushed_dependencies()             {
 427     assert(!has_flushed_dependencies(), "should only happen once");
 428     _has_flushed_dependencies = 1;
 429   }
 430 
 431   bool  is_marked_for_reclamation() const         { return _marked_for_reclamation; }
 432   void  mark_for_reclamation()                    { _marked_for_reclamation = 1; }
 433 
 434   bool  has_unsafe_access() const                 { return _has_unsafe_access; }
 435   void  set_has_unsafe_access(bool z)             { _has_unsafe_access = z; }
 436 
 437   bool  has_method_handle_invokes() const         { return _has_method_handle_invokes; }
 438   void  set_has_method_handle_invokes(bool z)     { _has_method_handle_invokes = z; }
 439 
 440   bool  is_speculatively_disconnected() const     { return _speculatively_disconnected; }
 441   void  set_speculatively_disconnected(bool z)    { _speculatively_disconnected = z; }
 442 
 443   bool  is_lazy_critical_native() const           { return _lazy_critical_native; }
 444   void  set_lazy_critical_native(bool z)          { _lazy_critical_native = z; }
 445 
 446   bool  has_wide_vectors() const                  { return _has_wide_vectors; }
 447   void  set_has_wide_vectors(bool z)              { _has_wide_vectors = z; }
 448 
 449   int   comp_level() const                        { return _comp_level; }
 450 
 451   // Support for oops in scopes and relocs:
 452   // Note: index 0 is reserved for null.
 453   oop   oop_at(int index) const                   { return index == 0 ? (oop) NULL: *oop_addr_at(index); }
 454   oop*  oop_addr_at(int index) const {  // for GC
 455     // relocation indexes are biased by 1 (because 0 is reserved)
 456     assert(index > 0 && index <= oops_size(), "must be a valid non-zero index");
 457     assert(!_oops_are_stale, "oops are stale");
 458     return &oops_begin()[index - 1];
 459   }
 460 
 461   // Support for meta data in scopes and relocs:
 462   // Note: index 0 is reserved for null.
 463   Metadata*     metadata_at(int index) const      { return index == 0 ? NULL: *metadata_addr_at(index); }
 464   Metadata**  metadata_addr_at(int index) const {  // for GC
 465     // relocation indexes are biased by 1 (because 0 is reserved)
 466     assert(index > 0 && index <= metadata_size(), "must be a valid non-zero index");
 467     return &metadata_begin()[index - 1];
 468   }
 469 
 470   void copy_values(GrowableArray<jobject>* oops);
 471   void copy_values(GrowableArray<Metadata*>* metadata);
 472 
 473   // Relocation support
 474 private:
 475   void fix_oop_relocations(address begin, address end, bool initialize_immediates);
 476   inline void initialize_immediate_oop(oop* dest, jobject handle);
 477 
 478 public:
 479   void fix_oop_relocations(address begin, address end) { fix_oop_relocations(begin, end, false); }
 480   void fix_oop_relocations()                           { fix_oop_relocations(NULL, NULL, false); }
 481   void verify_oop_relocations();
 482 
 483   bool is_at_poll_return(address pc);
 484   bool is_at_poll_or_poll_return(address pc);
 485 
 486   // Scavengable oop support
 487   bool  on_scavenge_root_list() const                  { return (_scavenge_root_state & 1) != 0; }
 488  protected:
 489   enum { sl_on_list = 0x01, sl_marked = 0x10 };
 490   void  set_on_scavenge_root_list()                    { _scavenge_root_state = sl_on_list; }
 491   void  clear_on_scavenge_root_list()                  { _scavenge_root_state = 0; }
 492   // assertion-checking and pruning logic uses the bits of _scavenge_root_state
 493 #ifndef PRODUCT
 494   void  set_scavenge_root_marked()                     { _scavenge_root_state |= sl_marked; }
 495   void  clear_scavenge_root_marked()                   { _scavenge_root_state &= ~sl_marked; }
 496   bool  scavenge_root_not_marked()                     { return (_scavenge_root_state &~ sl_on_list) == 0; }
 497   // N.B. there is no positive marked query, and we only use the not_marked query for asserts.
 498 #endif //PRODUCT
 499   nmethod* scavenge_root_link() const                  { return _scavenge_root_link; }
 500   void     set_scavenge_root_link(nmethod *n)          { _scavenge_root_link = n; }
 501 
 502   nmethod* saved_nmethod_link() const                  { return _saved_nmethod_link; }
 503   void     set_saved_nmethod_link(nmethod *n)          { _saved_nmethod_link = n; }
 504 
 505  public:
 506 
 507   // Sweeper support
 508   long  stack_traversal_mark()                    { return _stack_traversal_mark; }
 509   void  set_stack_traversal_mark(long l)          { _stack_traversal_mark = l; }
 510 
 511   // Exception cache support
 512   ExceptionCache* exception_cache() const         { return _exception_cache; }
 513   void set_exception_cache(ExceptionCache *ec)    { _exception_cache = ec; }
 514   address handler_for_exception_and_pc(Handle exception, address pc);
 515   void add_handler_for_exception_and_pc(Handle exception, address pc, address handler);
 516   void remove_from_exception_cache(ExceptionCache* ec);
 517 
 518   // implicit exceptions support
 519   address continuation_for_implicit_exception(address pc);
 520 
 521   // On-stack replacement support
 522   int   osr_entry_bci() const                     { assert(is_osr_method(), "wrong kind of nmethod"); return _entry_bci; }
 523   address  osr_entry() const                      { assert(is_osr_method(), "wrong kind of nmethod"); return _osr_entry_point; }
 524   void  invalidate_osr_method();
 525   nmethod* osr_link() const                       { return _osr_link; }
 526   void     set_osr_link(nmethod *n)               { _osr_link = n; }
 527 
 528   // tells whether frames described by this nmethod can be deoptimized
 529   // note: native wrappers cannot be deoptimized.
 530   bool can_be_deoptimized() const { return is_java_method(); }
 531 
 532   // Inline cache support
 533   void clear_inline_caches();
 534   void cleanup_inline_caches();
 535   bool inlinecache_check_contains(address addr) const {
 536     return (addr >= code_begin() && addr < verified_entry_point());
 537   }
 538 
 539   // Check that all metadata is still alive
 540   void verify_metadata_loaders(address low_boundary, BoolObjectClosure* is_alive);
 541 
 542   // unlink and deallocate this nmethod
 543   // Only NMethodSweeper class is expected to use this. NMethodSweeper is not
 544   // expected to use any other private methods/data in this class.
 545 
 546  protected:
 547   void flush();
 548 
 549  public:
 550   // When true is returned, it is unsafe to remove this nmethod even if
 551   // it is a zombie, since the VM or the ServiceThread might still be
 552   // using it.
 553   bool is_locked_by_vm() const                    { return _lock_count >0; }
 554 
 555   // See comment at definition of _last_seen_on_stack
 556   void mark_as_seen_on_stack();
 557   bool can_not_entrant_be_converted();
 558 
 559   // Evolution support. We make old (discarded) compiled methods point to new Method*s.
 560   void set_method(Method* method) { _method = method; }
 561 
 562   // GC support
 563   void do_unloading(BoolObjectClosure* is_alive, bool unloading_occurred);
 564   bool can_unload(BoolObjectClosure* is_alive, oop* root, bool unloading_occurred);
 565 
 566   void preserve_callee_argument_oops(frame fr, const RegisterMap *reg_map,
 567                                      OopClosure* f);
 568   void oops_do(OopClosure* f) { oops_do(f, false); }
 569   void oops_do(OopClosure* f, bool do_strong_roots_only);
 570   bool detect_scavenge_root_oops();
 571   void verify_scavenge_root_oops() PRODUCT_RETURN;
 572 
 573   bool test_set_oops_do_mark();
 574   static void oops_do_marking_prologue();
 575   static void oops_do_marking_epilogue();
 576   static bool oops_do_marking_is_active() { return _oops_do_mark_nmethods != NULL; }
 577   bool test_oops_do_mark() { return _oops_do_mark_link != NULL; }
 578 
 579   // ScopeDesc for an instruction
 580   ScopeDesc* scope_desc_at(address pc);
 581 
 582  private:
 583   ScopeDesc* scope_desc_in(address begin, address end);
 584 
 585   address* orig_pc_addr(const frame* fr) { return (address*) ((address)fr->unextended_sp() + _orig_pc_offset); }
 586 
 587   PcDesc* find_pc_desc_internal(address pc, bool approximate);
 588 
 589   PcDesc* find_pc_desc(address pc, bool approximate) {
 590     PcDesc* desc = _pc_desc_cache.last_pc_desc();
 591     if (desc != NULL && desc->pc_offset() == pc - code_begin()) {
 592       return desc;
 593     }
 594     return find_pc_desc_internal(pc, approximate);
 595   }
 596 
 597  public:
 598   // ScopeDesc retrieval operation
 599   PcDesc* pc_desc_at(address pc)   { return find_pc_desc(pc, false); }
 600   // pc_desc_near returns the first PcDesc at or after the givne pc.
 601   PcDesc* pc_desc_near(address pc) { return find_pc_desc(pc, true); }
 602 
 603  public:
 604   // copying of debugging information
 605   void copy_scopes_pcs(PcDesc* pcs, int count);
 606   void copy_scopes_data(address buffer, int size);
 607 
 608   // Deopt
 609   // Return true is the PC is one would expect if the frame is being deopted.
 610   bool is_deopt_pc      (address pc) { return is_deopt_entry(pc) || is_deopt_mh_entry(pc); }
 611   bool is_deopt_entry   (address pc) { return pc == deopt_handler_begin(); }
 612   bool is_deopt_mh_entry(address pc) { return pc == deopt_mh_handler_begin(); }
 613   // Accessor/mutator for the original pc of a frame before a frame was deopted.
 614   address get_original_pc(const frame* fr) { return *orig_pc_addr(fr); }
 615   void    set_original_pc(const frame* fr, address pc) { *orig_pc_addr(fr) = pc; }
 616 
 617   static address get_deopt_original_pc(const frame* fr);
 618 
 619   // MethodHandle
 620   bool is_method_handle_return(address return_pc);
 621 
 622   // jvmti support:
 623   void post_compiled_method_load_event();
 624   jmethodID get_and_cache_jmethod_id();
 625 
 626   // verify operations
 627   void verify();
 628   void verify_scopes();
 629   void verify_interrupt_point(address interrupt_point);
 630 
 631   // printing support
 632   void print()                          const;
 633   void print_code();
 634   void print_relocations()                        PRODUCT_RETURN;
 635   void print_pcs()                                PRODUCT_RETURN;
 636   void print_scopes()                             PRODUCT_RETURN;
 637   void print_dependencies()                       PRODUCT_RETURN;
 638   void print_value_on(outputStream* st) const     PRODUCT_RETURN;
 639   void print_calls(outputStream* st)              PRODUCT_RETURN;
 640   void print_handler_table()                      PRODUCT_RETURN;
 641   void print_nul_chk_table()                      PRODUCT_RETURN;
 642   void print_nmethod(bool print_code);
 643 
 644   // need to re-define this from CodeBlob else the overload hides it
 645   virtual void print_on(outputStream* st) const { CodeBlob::print_on(st); }
 646   void print_on(outputStream* st, const char* msg) const;
 647 
 648   // Logging
 649   void log_identity(xmlStream* log) const;
 650   void log_new_nmethod() const;
 651   void log_state_change() const;
 652 
 653   // Prints block-level comments, including nmethod specific block labels:
 654   virtual void print_block_comment(outputStream* stream, address block_begin) const {
 655     print_nmethod_labels(stream, block_begin);
 656     CodeBlob::print_block_comment(stream, block_begin);
 657   }
 658   void print_nmethod_labels(outputStream* stream, address block_begin) const;
 659 
 660   // Prints a comment for one native instruction (reloc info, pc desc)
 661   void print_code_comment_on(outputStream* st, int column, address begin, address end);
 662   static void print_statistics()                  PRODUCT_RETURN;
 663 
 664   // Compiler task identification.  Note that all OSR methods
 665   // are numbered in an independent sequence if CICountOSR is true,
 666   // and native method wrappers are also numbered independently if
 667   // CICountNative is true.
 668   int  compile_id() const                         { return _compile_id; }
 669   const char* compile_kind() const;
 670 
 671   // For debugging
 672   // CompiledIC*    IC_at(char* p) const;
 673   // PrimitiveIC*   primitiveIC_at(char* p) const;
 674   oop embeddedOop_at(address p);
 675 
 676   // tells if any of this method's dependencies have been invalidated
 677   // (this is expensive!)
 678   bool check_all_dependencies();
 679 
 680   // tells if this compiled method is dependent on the given changes,
 681   // and the changes have invalidated it
 682   bool check_dependency_on(DepChange& changes);
 683 
 684   // Evolution support. Tells if this compiled method is dependent on any of
 685   // methods m() of class dependee, such that if m() in dependee is replaced,
 686   // this compiled method will have to be deoptimized.
 687   bool is_evol_dependent_on(Klass* dependee);
 688 
 689   // Fast breakpoint support. Tells if this compiled method is
 690   // dependent on the given method. Returns true if this nmethod
 691   // corresponds to the given method as well.
 692   bool is_dependent_on_method(Method* dependee);
 693 
 694   // is it ok to patch at address?
 695   bool is_patchable_at(address instr_address);
 696 
 697   // UseBiasedLocking support
 698   ByteSize native_receiver_sp_offset() {
 699     return _native_receiver_sp_offset;
 700   }
 701   ByteSize native_basic_lock_sp_offset() {
 702     return _native_basic_lock_sp_offset;
 703   }
 704 
 705   // support for code generation
 706   static int verified_entry_point_offset()        { return offset_of(nmethod, _verified_entry_point); }
 707   static int osr_entry_point_offset()             { return offset_of(nmethod, _osr_entry_point); }
 708   static int entry_bci_offset()                   { return offset_of(nmethod, _entry_bci); }
 709 
 710   // RedefineClasses support.   Mark metadata in nmethods as on_stack so that
 711   // redefine classes doesn't purge it.
 712   static void mark_on_stack(nmethod* nm) {
 713     nm->metadata_do(Metadata::mark_on_stack);
 714   }
 715   void metadata_do(void f(Metadata*));
 716 };
 717 
 718 // Locks an nmethod so its code will not get removed and it will not
 719 // be made into a zombie, even if it is a not_entrant method. After the
 720 // nmethod becomes a zombie, if CompiledMethodUnload event processing
 721 // needs to be done, then lock_nmethod() is used directly to keep the
 722 // generated code from being reused too early.
 723 class nmethodLocker : public StackObj {
 724   nmethod* _nm;
 725 
 726  public:
 727 
 728   // note: nm can be NULL
 729   // Only JvmtiDeferredEvent::compiled_method_unload_event()
 730   // should pass zombie_ok == true.
 731   static void lock_nmethod(nmethod* nm, bool zombie_ok = false);
 732   static void unlock_nmethod(nmethod* nm); // (ditto)
 733 
 734   nmethodLocker(address pc); // derive nm from pc
 735   nmethodLocker(nmethod *nm) { _nm = nm; lock_nmethod(_nm); }
 736   nmethodLocker() { _nm = NULL; }
 737   ~nmethodLocker() { unlock_nmethod(_nm); }
 738 
 739   nmethod* code() { return _nm; }
 740   void set_code(nmethod* new_nm) {
 741     unlock_nmethod(_nm);   // note:  This works even if _nm==new_nm.
 742     _nm = new_nm;
 743     lock_nmethod(_nm);
 744   }
 745 };
 746 
 747 #endif // SHARE_VM_CODE_NMETHOD_HPP