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 
 123   static nmethod* volatile _oops_do_mark_nmethods;
 124   nmethod*        volatile _oops_do_mark_link;
 125 
 126   AbstractCompiler* _compiler; // The compiler which compiled this nmethod
 127 
 128   // offsets for entry points
 129   address _entry_point;                      // entry point with class check
 130   address _verified_entry_point;             // entry point without class check
 131   address _osr_entry_point;                  // entry point for on stack replacement
 132 
 133   // Offsets for different nmethod parts
 134   int _exception_offset;
 135   // All deoptee's will resume execution at this location described by
 136   // this offset.
 137   int _deoptimize_offset;
 138   // All deoptee's at a MethodHandle call site will resume execution
 139   // at this location described by this offset.
 140   int _deoptimize_mh_offset;
 141   // Offset of the unwind handler if it exists
 142   int _unwind_handler_offset;
 143 
 144 #ifdef HAVE_DTRACE_H
 145   int _trap_offset;
 146 #endif // def HAVE_DTRACE_H
 147   int _consts_offset;
 148   int _stub_offset;
 149   int _oops_offset;                       // offset to where embedded oop table begins (inside data)
 150   int _metadata_offset;                   // embedded meta data table
 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 
 168   bool _marked_for_reclamation;              // Used by NMethodSweeper (set only by sweeper)
 169   bool _marked_for_deoptimization;           // Used for stack deoptimization
 170 
 171   // used by jvmti to track if an unload event has been posted for this nmethod.
 172   bool _unload_reported;
 173 
 174   // set during construction
 175   unsigned int _has_unsafe_access:1;         // May fault due to unsafe access.
 176   unsigned int _has_method_handle_invokes:1; // Has this method MethodHandle invokes?
 177   unsigned int _lazy_critical_native:1;      // Lazy JNI critical native
 178   unsigned int _has_wide_vectors:1;          // Preserve wide vectors at safepoints
 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   // Nmethod Flushing lock. If non-zero, then the nmethod is not removed
 196   // and is not made into a zombie. However, once the nmethod is made into
 197   // a zombie, it will be locked one final time if CompiledMethodUnload
 198   // event processing needs to be done.
 199   jint  _lock_count;
 200 
 201   // not_entrant method removal. Each mark_sweep pass will update
 202   // this mark to current sweep invocation count if it is seen on the
 203   // stack.  An not_entrant method can be removed when there are no
 204   // more activations, i.e., when the _stack_traversal_mark is less than
 205   // current sweep traversal index.
 206   long _stack_traversal_mark;
 207 
 208   // The _hotness_counter indicates the hotness of a method. The higher
 209   // the value the hotter the method. The hotness counter of a nmethod is
 210   // set to [(ReservedCodeCacheSize / (1024 * 1024)) * 2] each time the method
 211   // is active while stack scanning (mark_active_nmethods()). The hotness
 212   // counter is decreased (by 1) while sweeping.
 213   int _hotness_counter;
 214 
 215   ExceptionCache *_exception_cache;
 216   PcDescCache     _pc_desc_cache;
 217 
 218   // These are used for compiled synchronized native methods to
 219   // locate the owner and stack slot for the BasicLock so that we can
 220   // properly revoke the bias of the owner if necessary. They are
 221   // needed because there is no debug information for compiled native
 222   // wrappers and the oop maps are insufficient to allow
 223   // frame::retrieve_receiver() to work. Currently they are expected
 224   // to be byte offsets from the Java stack pointer for maximum code
 225   // sharing between platforms. Note that currently biased locking
 226   // will never cause Class instances to be biased but this code
 227   // handles the static synchronized case as well.
 228   // JVMTI's GetLocalInstance() also uses these offsets to find the receiver
 229   // for non-static native wrapper frames.
 230   ByteSize _native_receiver_sp_offset;
 231   ByteSize _native_basic_lock_sp_offset;
 232 
 233   friend class nmethodLocker;
 234 
 235   // For native wrappers
 236   nmethod(Method* method,
 237           int nmethod_size,
 238           int compile_id,
 239           CodeOffsets* offsets,
 240           CodeBuffer *code_buffer,
 241           int frame_size,
 242           ByteSize basic_lock_owner_sp_offset, /* synchronized natives only */
 243           ByteSize basic_lock_sp_offset,       /* synchronized natives only */
 244           OopMapSet* oop_maps);
 245 
 246 #ifdef HAVE_DTRACE_H
 247   // For native wrappers
 248   nmethod(Method* method,
 249           int nmethod_size,
 250           CodeOffsets* offsets,
 251           CodeBuffer *code_buffer,
 252           int frame_size);
 253 #endif // def HAVE_DTRACE_H
 254 
 255   // Creation support
 256   nmethod(Method* method,
 257           int nmethod_size,
 258           int compile_id,
 259           int entry_bci,
 260           CodeOffsets* offsets,
 261           int orig_pc_offset,
 262           DebugInformationRecorder *recorder,
 263           Dependencies* dependencies,
 264           CodeBuffer *code_buffer,
 265           int frame_size,
 266           OopMapSet* oop_maps,
 267           ExceptionHandlerTable* handler_table,
 268           ImplicitExceptionTable* nul_chk_table,
 269           AbstractCompiler* compiler,
 270           int comp_level);
 271 
 272   // helper methods
 273   void* operator new(size_t size, int nmethod_size);
 274 
 275   const char* reloc_string_for(u_char* begin, u_char* end);
 276   // Returns true if this thread changed the state of the nmethod or
 277   // false if another thread performed the transition.
 278   bool make_not_entrant_or_zombie(unsigned int state);
 279   void inc_decompile_count();
 280 
 281   // Used to manipulate the exception cache
 282   void add_exception_cache_entry(ExceptionCache* new_entry);
 283   ExceptionCache* exception_cache_entry_for_exception(Handle exception);
 284 
 285   // Inform external interfaces that a compiled method has been unloaded
 286   void post_compiled_method_unload();
 287 
 288   // Initailize fields to their default values
 289   void init_defaults();
 290 
 291  public:
 292   // create nmethod with entry_bci
 293   static nmethod* new_nmethod(methodHandle method,
 294                               int compile_id,
 295                               int entry_bci,
 296                               CodeOffsets* offsets,
 297                               int orig_pc_offset,
 298                               DebugInformationRecorder* recorder,
 299                               Dependencies* dependencies,
 300                               CodeBuffer *code_buffer,
 301                               int frame_size,
 302                               OopMapSet* oop_maps,
 303                               ExceptionHandlerTable* handler_table,
 304                               ImplicitExceptionTable* nul_chk_table,
 305                               AbstractCompiler* compiler,
 306                               int comp_level);
 307 
 308   static nmethod* new_native_nmethod(methodHandle method,
 309                                      int compile_id,
 310                                      CodeBuffer *code_buffer,
 311                                      int vep_offset,
 312                                      int frame_complete,
 313                                      int frame_size,
 314                                      ByteSize receiver_sp_offset,
 315                                      ByteSize basic_lock_sp_offset,
 316                                      OopMapSet* oop_maps);
 317 
 318 #ifdef HAVE_DTRACE_H
 319   // The method we generate for a dtrace probe has to look
 320   // like an nmethod as far as the rest of the system is concerned
 321   // which is somewhat unfortunate.
 322   static nmethod* new_dtrace_nmethod(methodHandle method,
 323                                      CodeBuffer *code_buffer,
 324                                      int vep_offset,
 325                                      int trap_offset,
 326                                      int frame_complete,
 327                                      int frame_size);
 328 
 329   int trap_offset() const      { return _trap_offset; }
 330   address trap_address() const { return insts_begin() + _trap_offset; }
 331 
 332 #endif // def HAVE_DTRACE_H
 333 
 334   // accessors
 335   Method* method() const                          { return _method; }
 336   AbstractCompiler* compiler() const              { return _compiler; }
 337 
 338   // type info
 339   bool is_nmethod() const                         { return true; }
 340   bool is_java_method() const                     { return !method()->is_native(); }
 341   bool is_native_method() const                   { return method()->is_native(); }
 342   bool is_osr_method() const                      { return _entry_bci != InvocationEntryBci; }
 343 
 344   bool is_compiled_by_c1() const;
 345   bool is_compiled_by_c2() const;
 346   bool is_compiled_by_shark() const;
 347 
 348   // boundaries for different parts
 349   address consts_begin          () const          { return           header_begin() + _consts_offset        ; }
 350   address consts_end            () const          { return           header_begin() +  code_offset()        ; }
 351   address insts_begin           () const          { return           header_begin() +  code_offset()        ; }
 352   address insts_end             () const          { return           header_begin() + _stub_offset          ; }
 353   address stub_begin            () const          { return           header_begin() + _stub_offset          ; }
 354   address stub_end              () const          { return           header_begin() + _oops_offset          ; }
 355   address exception_begin       () const          { return           header_begin() + _exception_offset     ; }
 356   address deopt_handler_begin   () const          { return           header_begin() + _deoptimize_offset    ; }
 357   address deopt_mh_handler_begin() const          { return           header_begin() + _deoptimize_mh_offset ; }
 358   address unwind_handler_begin  () const          { return _unwind_handler_offset != -1 ? (header_begin() + _unwind_handler_offset) : NULL; }
 359   oop*    oops_begin            () const          { return (oop*)   (header_begin() + _oops_offset)         ; }
 360   oop*    oops_end              () const          { return (oop*)   (header_begin() + _metadata_offset)     ; }
 361 
 362   Metadata** metadata_begin   () const            { return (Metadata**)  (header_begin() + _metadata_offset)     ; }
 363   Metadata** metadata_end     () const            { return (Metadata**)  (header_begin() + _scopes_data_offset)  ; }
 364 
 365   address scopes_data_begin     () const          { return           header_begin() + _scopes_data_offset   ; }
 366   address scopes_data_end       () const          { return           header_begin() + _scopes_pcs_offset    ; }
 367   PcDesc* scopes_pcs_begin      () const          { return (PcDesc*)(header_begin() + _scopes_pcs_offset   ); }
 368   PcDesc* scopes_pcs_end        () const          { return (PcDesc*)(header_begin() + _dependencies_offset) ; }
 369   address dependencies_begin    () const          { return           header_begin() + _dependencies_offset  ; }
 370   address dependencies_end      () const          { return           header_begin() + _handler_table_offset ; }
 371   address handler_table_begin   () const          { return           header_begin() + _handler_table_offset ; }
 372   address handler_table_end     () const          { return           header_begin() + _nul_chk_table_offset ; }
 373   address nul_chk_table_begin   () const          { return           header_begin() + _nul_chk_table_offset ; }
 374   address nul_chk_table_end     () const          { return           header_begin() + _nmethod_end_offset   ; }
 375 
 376   // Sizes
 377   int consts_size       () const                  { return            consts_end       () -            consts_begin       (); }
 378   int insts_size        () const                  { return            insts_end        () -            insts_begin        (); }
 379   int stub_size         () const                  { return            stub_end         () -            stub_begin         (); }
 380   int oops_size         () const                  { return (address)  oops_end         () - (address)  oops_begin         (); }
 381   int metadata_size     () const                  { return (address)  metadata_end     () - (address)  metadata_begin     (); }
 382   int scopes_data_size  () const                  { return            scopes_data_end  () -            scopes_data_begin  (); }
 383   int scopes_pcs_size   () const                  { return (intptr_t) scopes_pcs_end   () - (intptr_t) scopes_pcs_begin   (); }
 384   int dependencies_size () const                  { return            dependencies_end () -            dependencies_begin (); }
 385   int handler_table_size() const                  { return            handler_table_end() -            handler_table_begin(); }
 386   int nul_chk_table_size() const                  { return            nul_chk_table_end() -            nul_chk_table_begin(); }
 387 
 388   int total_size        () const;
 389 
 390   void dec_hotness_counter()        { _hotness_counter--; }
 391   void set_hotness_counter(int val) { _hotness_counter = val; }
 392   int  hotness_counter() const      { return _hotness_counter; }
 393 
 394   // Containment
 395   bool consts_contains       (address addr) const { return consts_begin       () <= addr && addr < consts_end       (); }
 396   bool insts_contains        (address addr) const { return insts_begin        () <= addr && addr < insts_end        (); }
 397   bool stub_contains         (address addr) const { return stub_begin         () <= addr && addr < stub_end         (); }
 398   bool oops_contains         (oop*    addr) const { return oops_begin         () <= addr && addr < oops_end         (); }
 399   bool metadata_contains     (Metadata** addr) const   { return metadata_begin     () <= addr && addr < metadata_end     (); }
 400   bool scopes_data_contains  (address addr) const { return scopes_data_begin  () <= addr && addr < scopes_data_end  (); }
 401   bool scopes_pcs_contains   (PcDesc* addr) const { return scopes_pcs_begin   () <= addr && addr < scopes_pcs_end   (); }
 402   bool handler_table_contains(address addr) const { return handler_table_begin() <= addr && addr < handler_table_end(); }
 403   bool nul_chk_table_contains(address addr) const { return nul_chk_table_begin() <= addr && addr < nul_chk_table_end(); }
 404 
 405   // entry points
 406   address entry_point() const                     { return _entry_point;             } // normal entry point
 407   address verified_entry_point() const            { return _verified_entry_point;    } // if klass is correct
 408 
 409   // flag accessing and manipulation
 410   bool  is_in_use() const                         { return _state == alive; }
 411   bool  is_alive() const                          { return _state == alive || _state == not_entrant; }
 412   bool  is_not_entrant() const                    { return _state == not_entrant; }
 413   bool  is_zombie() const                         { return _state == zombie; }
 414   bool  is_unloaded() const                       { return _state == unloaded;   }
 415 
 416   // Make the nmethod non entrant. The nmethod will continue to be
 417   // alive.  It is used when an uncommon trap happens.  Returns true
 418   // if this thread changed the state of the nmethod or false if
 419   // another thread performed the transition.
 420   bool  make_not_entrant() { return make_not_entrant_or_zombie(not_entrant); }
 421   bool  make_zombie()      { return make_not_entrant_or_zombie(zombie); }
 422 
 423   // used by jvmti to track if the unload event has been reported
 424   bool  unload_reported()                         { return _unload_reported; }
 425   void  set_unload_reported()                     { _unload_reported = true; }
 426 
 427   bool  is_marked_for_deoptimization() const      { return _marked_for_deoptimization; }
 428   void  mark_for_deoptimization()                 { _marked_for_deoptimization = true; }
 429 
 430   void  make_unloaded(BoolObjectClosure* is_alive, oop cause);
 431 
 432   bool has_dependencies()                         { return dependencies_size() != 0; }
 433   void flush_dependencies(BoolObjectClosure* is_alive);
 434   bool has_flushed_dependencies()                 { return _has_flushed_dependencies; }
 435   void set_has_flushed_dependencies()             {
 436     assert(!has_flushed_dependencies(), "should only happen once");
 437     _has_flushed_dependencies = 1;
 438   }
 439 
 440   bool  is_marked_for_reclamation() const         { return _marked_for_reclamation; }
 441   void  mark_for_reclamation()                    { _marked_for_reclamation = 1; }
 442 
 443   bool  has_unsafe_access() const                 { return _has_unsafe_access; }
 444   void  set_has_unsafe_access(bool z)             { _has_unsafe_access = z; }
 445 
 446   bool  has_method_handle_invokes() const         { return _has_method_handle_invokes; }
 447   void  set_has_method_handle_invokes(bool z)     { _has_method_handle_invokes = z; }
 448 
 449   bool  is_lazy_critical_native() const           { return _lazy_critical_native; }
 450   void  set_lazy_critical_native(bool z)          { _lazy_critical_native = z; }
 451 
 452   bool  has_wide_vectors() const                  { return _has_wide_vectors; }
 453   void  set_has_wide_vectors(bool z)              { _has_wide_vectors = z; }
 454 
 455   int   comp_level() const                        { return _comp_level; }
 456 
 457   // Support for oops in scopes and relocs:
 458   // Note: index 0 is reserved for null.
 459   oop   oop_at(int index) const                   { return index == 0 ? (oop) NULL: *oop_addr_at(index); }
 460   oop*  oop_addr_at(int index) const {  // for GC
 461     // relocation indexes are biased by 1 (because 0 is reserved)
 462     assert(index > 0 && index <= oops_size(), "must be a valid non-zero index");
 463     assert(!_oops_are_stale, "oops are stale");
 464     return &oops_begin()[index - 1];
 465   }
 466 
 467   // Support for meta data in scopes and relocs:
 468   // Note: index 0 is reserved for null.
 469   Metadata*     metadata_at(int index) const      { return index == 0 ? NULL: *metadata_addr_at(index); }
 470   Metadata**  metadata_addr_at(int index) const {  // for GC
 471     // relocation indexes are biased by 1 (because 0 is reserved)
 472     assert(index > 0 && index <= metadata_size(), "must be a valid non-zero index");
 473     return &metadata_begin()[index - 1];
 474   }
 475 
 476   void copy_values(GrowableArray<jobject>* oops);
 477   void copy_values(GrowableArray<Metadata*>* metadata);
 478 
 479   // Relocation support
 480 private:
 481   void fix_oop_relocations(address begin, address end, bool initialize_immediates);
 482   inline void initialize_immediate_oop(oop* dest, jobject handle);
 483 
 484 public:
 485   void fix_oop_relocations(address begin, address end) { fix_oop_relocations(begin, end, false); }
 486   void fix_oop_relocations()                           { fix_oop_relocations(NULL, NULL, false); }
 487   void verify_oop_relocations();
 488 
 489   bool is_at_poll_return(address pc);
 490   bool is_at_poll_or_poll_return(address pc);
 491 
 492   // Scavengable oop support
 493   bool  on_scavenge_root_list() const                  { return (_scavenge_root_state & 1) != 0; }
 494  protected:
 495   enum { sl_on_list = 0x01, sl_marked = 0x10 };
 496   void  set_on_scavenge_root_list()                    { _scavenge_root_state = sl_on_list; }
 497   void  clear_on_scavenge_root_list()                  { _scavenge_root_state = 0; }
 498   // assertion-checking and pruning logic uses the bits of _scavenge_root_state
 499 #ifndef PRODUCT
 500   void  set_scavenge_root_marked()                     { _scavenge_root_state |= sl_marked; }
 501   void  clear_scavenge_root_marked()                   { _scavenge_root_state &= ~sl_marked; }
 502   bool  scavenge_root_not_marked()                     { return (_scavenge_root_state &~ sl_on_list) == 0; }
 503   // N.B. there is no positive marked query, and we only use the not_marked query for asserts.
 504 #endif //PRODUCT
 505   nmethod* scavenge_root_link() const                  { return _scavenge_root_link; }
 506   void     set_scavenge_root_link(nmethod *n)          { _scavenge_root_link = n; }
 507 
 508  public:
 509 
 510   // Sweeper support
 511   long  stack_traversal_mark()                    { return _stack_traversal_mark; }
 512   void  set_stack_traversal_mark(long l)          { _stack_traversal_mark = l; }
 513 
 514   // Exception cache support
 515   ExceptionCache* exception_cache() const         { return _exception_cache; }
 516   void set_exception_cache(ExceptionCache *ec)    { _exception_cache = ec; }
 517   address handler_for_exception_and_pc(Handle exception, address pc);
 518   void add_handler_for_exception_and_pc(Handle exception, address pc, address handler);
 519   void remove_from_exception_cache(ExceptionCache* ec);
 520 
 521   // implicit exceptions support
 522   address continuation_for_implicit_exception(address pc);
 523 
 524   // On-stack replacement support
 525   int   osr_entry_bci() const                     { assert(is_osr_method(), "wrong kind of nmethod"); return _entry_bci; }
 526   address  osr_entry() const                      { assert(is_osr_method(), "wrong kind of nmethod"); return _osr_entry_point; }
 527   void  invalidate_osr_method();
 528   nmethod* osr_link() const                       { return _osr_link; }
 529   void     set_osr_link(nmethod *n)               { _osr_link = n; }
 530 
 531   // tells whether frames described by this nmethod can be deoptimized
 532   // note: native wrappers cannot be deoptimized.
 533   bool can_be_deoptimized() const { return is_java_method(); }
 534 
 535   // Inline cache support
 536   void clear_inline_caches();
 537   void cleanup_inline_caches();
 538   bool inlinecache_check_contains(address addr) const {
 539     return (addr >= code_begin() && addr < verified_entry_point());
 540   }
 541 
 542   // Check that all metadata is still alive
 543   void verify_metadata_loaders(address low_boundary, BoolObjectClosure* is_alive);
 544 
 545   // unlink and deallocate this nmethod
 546   // Only NMethodSweeper class is expected to use this. NMethodSweeper is not
 547   // expected to use any other private methods/data in this class.
 548 
 549  protected:
 550   void flush();
 551 
 552  public:
 553   // When true is returned, it is unsafe to remove this nmethod even if
 554   // it is a zombie, since the VM or the ServiceThread might still be
 555   // using it.
 556   bool is_locked_by_vm() const                    { return _lock_count >0; }
 557 
 558   // See comment at definition of _last_seen_on_stack
 559   void mark_as_seen_on_stack();
 560   bool can_not_entrant_be_converted();
 561 
 562   // Evolution support. We make old (discarded) compiled methods point to new Method*s.
 563   void set_method(Method* method) { _method = method; }
 564 
 565   // GC support
 566   void do_unloading(BoolObjectClosure* is_alive, bool unloading_occurred);
 567   bool can_unload(BoolObjectClosure* is_alive, oop* root, bool unloading_occurred);
 568 
 569   void preserve_callee_argument_oops(frame fr, const RegisterMap *reg_map,
 570                                      OopClosure* f);
 571   void oops_do(OopClosure* f) { oops_do(f, false); }
 572   void oops_do(OopClosure* f, bool allow_zombie);
 573   bool detect_scavenge_root_oops();
 574   void verify_scavenge_root_oops() PRODUCT_RETURN;
 575 
 576   bool test_set_oops_do_mark();
 577   static void oops_do_marking_prologue();
 578   static void oops_do_marking_epilogue();
 579   static bool oops_do_marking_is_active() { return _oops_do_mark_nmethods != NULL; }
 580   bool test_oops_do_mark() { return _oops_do_mark_link != NULL; }
 581 
 582   // ScopeDesc for an instruction
 583   ScopeDesc* scope_desc_at(address pc);
 584 
 585  private:
 586   ScopeDesc* scope_desc_in(address begin, address end);
 587 
 588   address* orig_pc_addr(const frame* fr) { return (address*) ((address)fr->unextended_sp() + _orig_pc_offset); }
 589 
 590   PcDesc* find_pc_desc_internal(address pc, bool approximate);
 591 
 592   PcDesc* find_pc_desc(address pc, bool approximate) {
 593     PcDesc* desc = _pc_desc_cache.last_pc_desc();
 594     if (desc != NULL && desc->pc_offset() == pc - code_begin()) {
 595       return desc;
 596     }
 597     return find_pc_desc_internal(pc, approximate);
 598   }
 599 
 600  public:
 601   // ScopeDesc retrieval operation
 602   PcDesc* pc_desc_at(address pc)   { return find_pc_desc(pc, false); }
 603   // pc_desc_near returns the first PcDesc at or after the givne pc.
 604   PcDesc* pc_desc_near(address pc) { return find_pc_desc(pc, true); }
 605 
 606  public:
 607   // copying of debugging information
 608   void copy_scopes_pcs(PcDesc* pcs, int count);
 609   void copy_scopes_data(address buffer, int size);
 610 
 611   // Deopt
 612   // Return true is the PC is one would expect if the frame is being deopted.
 613   bool is_deopt_pc      (address pc) { return is_deopt_entry(pc) || is_deopt_mh_entry(pc); }
 614   bool is_deopt_entry   (address pc) { return pc == deopt_handler_begin(); }
 615   bool is_deopt_mh_entry(address pc) { return pc == deopt_mh_handler_begin(); }
 616   // Accessor/mutator for the original pc of a frame before a frame was deopted.
 617   address get_original_pc(const frame* fr) { return *orig_pc_addr(fr); }
 618   void    set_original_pc(const frame* fr, address pc) { *orig_pc_addr(fr) = pc; }
 619 
 620   static address get_deopt_original_pc(const frame* fr);
 621 
 622   // MethodHandle
 623   bool is_method_handle_return(address return_pc);
 624 
 625   // jvmti support:
 626   void post_compiled_method_load_event();
 627   jmethodID get_and_cache_jmethod_id();
 628 
 629   // verify operations
 630   void verify();
 631   void verify_scopes();
 632   void verify_interrupt_point(address interrupt_point);
 633 
 634   // printing support
 635   void print()                          const;
 636   void print_code();
 637   void print_relocations()                        PRODUCT_RETURN;
 638   void print_pcs()                                PRODUCT_RETURN;
 639   void print_scopes()                             PRODUCT_RETURN;
 640   void print_dependencies()                       PRODUCT_RETURN;
 641   void print_value_on(outputStream* st) const     PRODUCT_RETURN;
 642   void print_calls(outputStream* st)              PRODUCT_RETURN;
 643   void print_handler_table()                      PRODUCT_RETURN;
 644   void print_nul_chk_table()                      PRODUCT_RETURN;
 645   void print_nmethod(bool print_code);
 646 
 647   // need to re-define this from CodeBlob else the overload hides it
 648   virtual void print_on(outputStream* st) const { CodeBlob::print_on(st); }
 649   void print_on(outputStream* st, const char* msg) const;
 650 
 651   // Logging
 652   void log_identity(xmlStream* log) const;
 653   void log_new_nmethod() const;
 654   void log_state_change() const;
 655 
 656   // Prints block-level comments, including nmethod specific block labels:
 657   virtual void print_block_comment(outputStream* stream, address block_begin) const {
 658     print_nmethod_labels(stream, block_begin);
 659     CodeBlob::print_block_comment(stream, block_begin);
 660   }
 661   void print_nmethod_labels(outputStream* stream, address block_begin) const;
 662 
 663   // Prints a comment for one native instruction (reloc info, pc desc)
 664   void print_code_comment_on(outputStream* st, int column, address begin, address end);
 665   static void print_statistics()                  PRODUCT_RETURN;
 666 
 667   // Compiler task identification.  Note that all OSR methods
 668   // are numbered in an independent sequence if CICountOSR is true,
 669   // and native method wrappers are also numbered independently if
 670   // CICountNative is true.
 671   int  compile_id() const                         { return _compile_id; }
 672   const char* compile_kind() const;
 673 
 674   // For debugging
 675   // CompiledIC*    IC_at(char* p) const;
 676   // PrimitiveIC*   primitiveIC_at(char* p) const;
 677   oop embeddedOop_at(address p);
 678 
 679   // tells if any of this method's dependencies have been invalidated
 680   // (this is expensive!)
 681   bool check_all_dependencies();
 682 
 683   // tells if this compiled method is dependent on the given changes,
 684   // and the changes have invalidated it
 685   bool check_dependency_on(DepChange& changes);
 686 
 687   // Evolution support. Tells if this compiled method is dependent on any of
 688   // methods m() of class dependee, such that if m() in dependee is replaced,
 689   // this compiled method will have to be deoptimized.
 690   bool is_evol_dependent_on(Klass* dependee);
 691 
 692   // Fast breakpoint support. Tells if this compiled method is
 693   // dependent on the given method. Returns true if this nmethod
 694   // corresponds to the given method as well.
 695   bool is_dependent_on_method(Method* dependee);
 696 
 697   // is it ok to patch at address?
 698   bool is_patchable_at(address instr_address);
 699 
 700   // UseBiasedLocking support
 701   ByteSize native_receiver_sp_offset() {
 702     return _native_receiver_sp_offset;
 703   }
 704   ByteSize native_basic_lock_sp_offset() {
 705     return _native_basic_lock_sp_offset;
 706   }
 707 
 708   // support for code generation
 709   static int verified_entry_point_offset()        { return offset_of(nmethod, _verified_entry_point); }
 710   static int osr_entry_point_offset()             { return offset_of(nmethod, _osr_entry_point); }
 711   static int entry_bci_offset()                   { return offset_of(nmethod, _entry_bci); }
 712 
 713   // RedefineClasses support.   Mark metadata in nmethods as on_stack so that
 714   // redefine classes doesn't purge it.
 715   static void mark_on_stack(nmethod* nm) {
 716     nm->metadata_do(Metadata::mark_on_stack);
 717   }
 718   void metadata_do(void f(Metadata*));
 719 };
 720 
 721 // Locks an nmethod so its code will not get removed and it will not
 722 // be made into a zombie, even if it is a not_entrant method. After the
 723 // nmethod becomes a zombie, if CompiledMethodUnload event processing
 724 // needs to be done, then lock_nmethod() is used directly to keep the
 725 // generated code from being reused too early.
 726 class nmethodLocker : public StackObj {
 727   nmethod* _nm;
 728 
 729  public:
 730 
 731   // note: nm can be NULL
 732   // Only JvmtiDeferredEvent::compiled_method_unload_event()
 733   // should pass zombie_ok == true.
 734   static void lock_nmethod(nmethod* nm, bool zombie_ok = false);
 735   static void unlock_nmethod(nmethod* nm); // (ditto)
 736 
 737   nmethodLocker(address pc); // derive nm from pc
 738   nmethodLocker(nmethod *nm) { _nm = nm; lock_nmethod(_nm); }
 739   nmethodLocker() { _nm = NULL; }
 740   ~nmethodLocker() { unlock_nmethod(_nm); }
 741 
 742   nmethod* code() { return _nm; }
 743   void set_code(nmethod* new_nm) {
 744     unlock_nmethod(_nm);   // note:  This works even if _nm==new_nm.
 745     _nm = new_nm;
 746     lock_nmethod(_nm);
 747   }
 748 };
 749 
 750 #endif // SHARE_VM_CODE_NMETHOD_HPP