1 /*
   2  * Copyright 1997-2009 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  20  * CA 95054 USA or visit www.sun.com if you need additional information or
  21  * have any questions.
  22  *
  23  */
  24 
  25 // This class is used internally by nmethods, to cache
  26 // exception/pc/handler information.
  27 
  28 class ExceptionCache : public CHeapObj {
  29   friend class VMStructs;
  30  private:
  31   static address _unwind_handler;
  32   enum { cache_size = 16 };
  33   klassOop _exception_type;
  34   address  _pc[cache_size];
  35   address  _handler[cache_size];
  36   int      _count;
  37   ExceptionCache* _next;
  38 
  39   address pc_at(int index)                     { assert(index >= 0 && index < count(),""); return _pc[index]; }
  40   void    set_pc_at(int index, address a)      { assert(index >= 0 && index < cache_size,""); _pc[index] = a; }
  41   address handler_at(int index)                { assert(index >= 0 && index < count(),""); return _handler[index]; }
  42   void    set_handler_at(int index, address a) { assert(index >= 0 && index < cache_size,""); _handler[index] = a; }
  43   int     count()                              { return _count; }
  44   void    increment_count()                    { _count++; }
  45 
  46  public:
  47 
  48   ExceptionCache(Handle exception, address pc, address handler);
  49 
  50   klassOop  exception_type()                { return _exception_type; }
  51   klassOop* exception_type_addr()           { return &_exception_type; }
  52   ExceptionCache* next()                    { return _next; }
  53   void      set_next(ExceptionCache *ec)    { _next = ec; }
  54 
  55   address match(Handle exception, address pc);
  56   bool    match_exception_with_space(Handle exception) ;
  57   address test_address(address addr);
  58   bool    add_address_and_handler(address addr, address handler) ;
  59 
  60   static address unwind_handler() { return _unwind_handler; }
  61 };
  62 
  63 
  64 // cache pc descs found in earlier inquiries
  65 class PcDescCache VALUE_OBJ_CLASS_SPEC {
  66   friend class VMStructs;
  67  private:
  68   enum { cache_size = 4 };
  69   PcDesc* _last_pc_desc;         // most recent pc_desc found
  70   PcDesc* _pc_descs[cache_size]; // last cache_size pc_descs found
  71  public:
  72   PcDescCache() { debug_only(_last_pc_desc = NULL); }
  73   void    reset_to(PcDesc* initial_pc_desc);
  74   PcDesc* find_pc_desc(int pc_offset, bool approximate);
  75   void    add_pc_desc(PcDesc* pc_desc);
  76   PcDesc* last_pc_desc() { return _last_pc_desc; }
  77 };
  78 
  79 
  80 // nmethods (native methods) are the compiled code versions of Java methods.
  81 
  82 struct nmFlags {
  83   friend class VMStructs;
  84   unsigned int version:8;                    // version number (0 = first version)
  85   unsigned int level:4;                      // optimization level
  86   unsigned int age:4;                        // age (in # of sweep steps)
  87 
  88   unsigned int state:2;                      // {alive, zombie, unloaded)
  89 
  90   unsigned int isUncommonRecompiled:1;       // recompiled because of uncommon trap?
  91   unsigned int isToBeRecompiled:1;           // to be recompiled as soon as it matures
  92   unsigned int hasFlushedDependencies:1;     // Used for maintenance of dependencies
  93   unsigned int markedForReclamation:1;       // Used by NMethodSweeper
  94 
  95   unsigned int has_unsafe_access:1;          // May fault due to unsafe access.
  96   unsigned int has_method_handle_invokes:1;  // Has this method MethodHandle invokes?
  97 
  98   void clear();
  99 };
 100 
 101 
 102 // A nmethod contains:
 103 //  - header                 (the nmethod structure)
 104 //  [Relocation]
 105 //  - relocation information
 106 //  - constant part          (doubles, longs and floats used in nmethod)
 107 //  [Code]
 108 //  - code body
 109 //  - exception handler
 110 //  - stub code
 111 //  [Debugging information]
 112 //  - oop array
 113 //  - data array
 114 //  - pcs
 115 //  [Exception handler table]
 116 //  - handler entry point array
 117 //  [Implicit Null Pointer exception table]
 118 //  - implicit null table array
 119 
 120 class Dependencies;
 121 class ExceptionHandlerTable;
 122 class ImplicitExceptionTable;
 123 class AbstractCompiler;
 124 class xmlStream;
 125 
 126 class nmethod : public CodeBlob {
 127   friend class VMStructs;
 128   friend class NMethodSweeper;
 129   friend class CodeCache;  // non-perm oops
 130  private:
 131   // Shared fields for all nmethod's
 132   static int _zombie_instruction_size;
 133 
 134   methodOop _method;
 135   int       _entry_bci;        // != InvocationEntryBci if this nmethod is an on-stack replacement method
 136 
 137   // To support simple linked-list chaining of nmethods:
 138   nmethod*  _osr_link;         // from instanceKlass::osr_nmethods_head
 139   nmethod*  _scavenge_root_link; // from CodeCache::scavenge_root_nmethods
 140 
 141   static nmethod* volatile _oops_do_mark_nmethods;
 142   nmethod*        volatile _oops_do_mark_link;
 143 
 144   AbstractCompiler* _compiler; // The compiler which compiled this nmethod
 145 
 146   // Offsets for different nmethod parts
 147   int _exception_offset;
 148   // All deoptee's will resume execution at this location described by this offset
 149   int _deoptimize_offset;
 150 #ifdef HAVE_DTRACE_H
 151   int _trap_offset;
 152 #endif // def HAVE_DTRACE_H
 153   int _stub_offset;
 154   int _consts_offset;
 155   int _scopes_data_offset;
 156   int _scopes_pcs_offset;
 157   int _dependencies_offset;
 158   int _handler_table_offset;
 159   int _nul_chk_table_offset;
 160   int _nmethod_end_offset;
 161 
 162   // location in frame (offset for sp) that deopt can store the original
 163   // pc during a deopt.
 164   int _orig_pc_offset;
 165 
 166   int _compile_id;                     // which compilation made this nmethod
 167   int _comp_level;                     // compilation level
 168 
 169   // offsets for entry points
 170   address _entry_point;                // entry point with class check
 171   address _verified_entry_point;       // entry point without class check
 172   address _osr_entry_point;            // entry point for on stack replacement
 173 
 174   nmFlags flags;           // various flags to keep track of nmethod state
 175   bool _markedForDeoptimization;       // Used for stack deoptimization
 176   enum { alive        = 0,
 177          not_entrant  = 1, // uncommon trap has happened but activations may still exist
 178          zombie       = 2,
 179          unloaded     = 3 };
 180 
 181   // used by jvmti to track if an unload event has been posted for this nmethod.
 182   bool _unload_reported;
 183 
 184   jbyte _scavenge_root_state;
 185 
 186   NOT_PRODUCT(bool _has_debug_info; )
 187 
 188   // Nmethod Flushing lock (if non-zero, then the nmethod is not removed)
 189   jint  _lock_count;
 190 
 191   // not_entrant method removal. Each mark_sweep pass will update
 192   // this mark to current sweep invocation count if it is seen on the
 193   // stack.  An not_entrant method can be removed when there is no
 194   // more activations, i.e., when the _stack_traversal_mark is less than
 195   // current sweep traversal index.
 196   long _stack_traversal_mark;
 197 
 198   ExceptionCache *_exception_cache;
 199   PcDescCache     _pc_desc_cache;
 200 
 201   // These are only used for compiled synchronized native methods to
 202   // locate the owner and stack slot for the BasicLock so that we can
 203   // properly revoke the bias of the owner if necessary. They are
 204   // needed because there is no debug information for compiled native
 205   // wrappers and the oop maps are insufficient to allow
 206   // frame::retrieve_receiver() to work. Currently they are expected
 207   // to be byte offsets from the Java stack pointer for maximum code
 208   // sharing between platforms. Note that currently biased locking
 209   // will never cause Class instances to be biased but this code
 210   // handles the static synchronized case as well.
 211   ByteSize _compiled_synchronized_native_basic_lock_owner_sp_offset;
 212   ByteSize _compiled_synchronized_native_basic_lock_sp_offset;
 213 
 214   friend class nmethodLocker;
 215 
 216   // For native wrappers
 217   nmethod(methodOop method,
 218           int nmethod_size,
 219           CodeOffsets* offsets,
 220           CodeBuffer *code_buffer,
 221           int frame_size,
 222           ByteSize basic_lock_owner_sp_offset, /* synchronized natives only */
 223           ByteSize basic_lock_sp_offset,       /* synchronized natives only */
 224           OopMapSet* oop_maps);
 225 
 226 #ifdef HAVE_DTRACE_H
 227   // For native wrappers
 228   nmethod(methodOop method,
 229           int nmethod_size,
 230           CodeOffsets* offsets,
 231           CodeBuffer *code_buffer,
 232           int frame_size);
 233 #endif // def HAVE_DTRACE_H
 234 
 235   // Creation support
 236   nmethod(methodOop method,
 237           int nmethod_size,
 238           int compile_id,
 239           int entry_bci,
 240           CodeOffsets* offsets,
 241           int orig_pc_offset,
 242           DebugInformationRecorder *recorder,
 243           Dependencies* dependencies,
 244           CodeBuffer *code_buffer,
 245           int frame_size,
 246           OopMapSet* oop_maps,
 247           ExceptionHandlerTable* handler_table,
 248           ImplicitExceptionTable* nul_chk_table,
 249           AbstractCompiler* compiler,
 250           int comp_level);
 251 
 252   // helper methods
 253   void* operator new(size_t size, int nmethod_size);
 254 
 255   const char* reloc_string_for(u_char* begin, u_char* end);
 256   // Returns true if this thread changed the state of the nmethod or
 257   // false if another thread performed the transition.
 258   bool make_not_entrant_or_zombie(unsigned int state);
 259   void inc_decompile_count();
 260 
 261   // used to check that writes to nmFlags are done consistently.
 262   static void check_safepoint() PRODUCT_RETURN;
 263 
 264   // Used to manipulate the exception cache
 265   void add_exception_cache_entry(ExceptionCache* new_entry);
 266   ExceptionCache* exception_cache_entry_for_exception(Handle exception);
 267 
 268   // Inform external interfaces that a compiled method has been unloaded
 269   inline void post_compiled_method_unload();
 270 
 271  public:
 272   // create nmethod with entry_bci
 273   static nmethod* new_nmethod(methodHandle method,
 274                               int compile_id,
 275                               int entry_bci,
 276                               CodeOffsets* offsets,
 277                               int orig_pc_offset,
 278                               DebugInformationRecorder* recorder,
 279                               Dependencies* dependencies,
 280                               CodeBuffer *code_buffer,
 281                               int frame_size,
 282                               OopMapSet* oop_maps,
 283                               ExceptionHandlerTable* handler_table,
 284                               ImplicitExceptionTable* nul_chk_table,
 285                               AbstractCompiler* compiler,
 286                               int comp_level);
 287 
 288   static nmethod* new_native_nmethod(methodHandle method,
 289                                      CodeBuffer *code_buffer,
 290                                      int vep_offset,
 291                                      int frame_complete,
 292                                      int frame_size,
 293                                      ByteSize receiver_sp_offset,
 294                                      ByteSize basic_lock_sp_offset,
 295                                      OopMapSet* oop_maps);
 296 
 297 #ifdef HAVE_DTRACE_H
 298   // The method we generate for a dtrace probe has to look
 299   // like an nmethod as far as the rest of the system is concerned
 300   // which is somewhat unfortunate.
 301   static nmethod* new_dtrace_nmethod(methodHandle method,
 302                                      CodeBuffer *code_buffer,
 303                                      int vep_offset,
 304                                      int trap_offset,
 305                                      int frame_complete,
 306                                      int frame_size);
 307 
 308   int trap_offset() const      { return _trap_offset; }
 309   address trap_address() const { return code_begin() + _trap_offset; }
 310 
 311 #endif // def HAVE_DTRACE_H
 312 
 313   // accessors
 314   methodOop method() const                        { return _method; }
 315   AbstractCompiler* compiler() const              { return _compiler; }
 316 
 317 #ifndef PRODUCT
 318   bool has_debug_info() const                     { return _has_debug_info; }
 319   void set_has_debug_info(bool f)                 { _has_debug_info = false; }
 320 #endif // NOT PRODUCT
 321 
 322   // type info
 323   bool is_nmethod() const                         { return true; }
 324   bool is_java_method() const                     { return !method()->is_native(); }
 325   bool is_native_method() const                   { return method()->is_native(); }
 326   bool is_osr_method() const                      { return _entry_bci != InvocationEntryBci; }
 327 
 328   bool is_compiled_by_c1() const;
 329   bool is_compiled_by_c2() const;
 330 
 331   // boundaries for different parts
 332   address code_begin         () const             { return _entry_point; }
 333   address code_end           () const             { return           header_begin() + _stub_offset          ; }
 334   address exception_begin    () const             { return           header_begin() + _exception_offset     ; }
 335   address deopt_handler_begin() const             { return           header_begin() + _deoptimize_offset    ; }
 336   address stub_begin         () const             { return           header_begin() + _stub_offset          ; }
 337   address stub_end           () const             { return           header_begin() + _consts_offset        ; }
 338   address consts_begin       () const             { return           header_begin() + _consts_offset        ; }
 339   address consts_end         () const             { return           header_begin() + _scopes_data_offset   ; }
 340   address scopes_data_begin  () const             { return           header_begin() + _scopes_data_offset   ; }
 341   address scopes_data_end    () const             { return           header_begin() + _scopes_pcs_offset    ; }
 342   PcDesc* scopes_pcs_begin   () const             { return (PcDesc*)(header_begin() + _scopes_pcs_offset   ); }
 343   PcDesc* scopes_pcs_end     () const             { return (PcDesc*)(header_begin() + _dependencies_offset); }
 344   address dependencies_begin () const             { return           header_begin() + _dependencies_offset ; }
 345   address dependencies_end   () const             { return           header_begin() + _handler_table_offset ; }
 346   address handler_table_begin() const             { return           header_begin() + _handler_table_offset ; }
 347   address handler_table_end  () const             { return           header_begin() + _nul_chk_table_offset   ; }
 348   address nul_chk_table_begin() const             { return           header_begin() + _nul_chk_table_offset ; }
 349   address nul_chk_table_end  () const             { return           header_begin() + _nmethod_end_offset   ; }
 350 
 351   int code_size         () const                  { return      code_end         () -      code_begin         (); }
 352   int stub_size         () const                  { return      stub_end         () -      stub_begin         (); }
 353   int consts_size       () const                  { return      consts_end       () -      consts_begin       (); }
 354   int scopes_data_size  () const                  { return      scopes_data_end  () -      scopes_data_begin  (); }
 355   int scopes_pcs_size   () const                  { return (intptr_t)scopes_pcs_end   () - (intptr_t)scopes_pcs_begin   (); }
 356   int dependencies_size () const                  { return      dependencies_end () -      dependencies_begin (); }
 357   int handler_table_size() const                  { return      handler_table_end() -      handler_table_begin(); }
 358   int nul_chk_table_size() const                  { return      nul_chk_table_end() -      nul_chk_table_begin(); }
 359 
 360   int total_size        () const;
 361 
 362   bool code_contains         (address addr) const { return code_begin         () <= addr && addr < code_end         (); }
 363   bool stub_contains         (address addr) const { return stub_begin         () <= addr && addr < stub_end         (); }
 364   bool consts_contains       (address addr) const { return consts_begin       () <= addr && addr < consts_end       (); }
 365   bool scopes_data_contains  (address addr) const { return scopes_data_begin  () <= addr && addr < scopes_data_end  (); }
 366   bool scopes_pcs_contains   (PcDesc* addr) const { return scopes_pcs_begin   () <= addr && addr < scopes_pcs_end   (); }
 367   bool handler_table_contains(address addr) const { return handler_table_begin() <= addr && addr < handler_table_end(); }
 368   bool nul_chk_table_contains(address addr) const { return nul_chk_table_begin() <= addr && addr < nul_chk_table_end(); }
 369 
 370   // entry points
 371   address entry_point() const                     { return _entry_point;             } // normal entry point
 372   address verified_entry_point() const            { return _verified_entry_point;    } // if klass is correct
 373 
 374   // flag accessing and manipulation
 375   bool  is_in_use() const                         { return flags.state == alive; }
 376   bool  is_alive() const                          { return flags.state == alive || flags.state == not_entrant; }
 377   bool  is_not_entrant() const                    { return flags.state == not_entrant; }
 378   bool  is_zombie() const                         { return flags.state == zombie; }
 379   bool  is_unloaded() const                       { return flags.state == unloaded;   }
 380 
 381   // Make the nmethod non entrant. The nmethod will continue to be
 382   // alive.  It is used when an uncommon trap happens.  Returns true
 383   // if this thread changed the state of the nmethod or false if
 384   // another thread performed the transition.
 385   bool  make_not_entrant()                        { return make_not_entrant_or_zombie(not_entrant); }
 386   bool  make_zombie()                             { return make_not_entrant_or_zombie(zombie); }
 387 
 388   // used by jvmti to track if the unload event has been reported
 389   bool  unload_reported()                         { return _unload_reported; }
 390   void  set_unload_reported()                     { _unload_reported = true; }
 391 
 392   bool  is_marked_for_deoptimization() const      { return _markedForDeoptimization; }
 393   void  mark_for_deoptimization()                 { _markedForDeoptimization = true; }
 394 
 395   void  make_unloaded(BoolObjectClosure* is_alive, oop cause);
 396 
 397   bool has_dependencies()                         { return dependencies_size() != 0; }
 398   void flush_dependencies(BoolObjectClosure* is_alive);
 399   bool  has_flushed_dependencies()                { return flags.hasFlushedDependencies; }
 400   void  set_has_flushed_dependencies()            {
 401     check_safepoint();
 402     assert(!has_flushed_dependencies(), "should only happen once");
 403     flags.hasFlushedDependencies = 1;
 404   }
 405 
 406   bool  is_marked_for_reclamation() const         { return flags.markedForReclamation; }
 407   void  mark_for_reclamation()                    { check_safepoint(); flags.markedForReclamation = 1; }
 408   void  unmark_for_reclamation()                  { check_safepoint(); flags.markedForReclamation = 0; }
 409 
 410   bool  has_unsafe_access() const                 { return flags.has_unsafe_access; }
 411   void  set_has_unsafe_access(bool z)             { flags.has_unsafe_access = z; }
 412 
 413   bool  has_method_handle_invokes() const         { return flags.has_method_handle_invokes; }
 414   void  set_has_method_handle_invokes(bool z)     { flags.has_method_handle_invokes = z; }
 415 
 416   int   level() const                             { return flags.level; }
 417   void  set_level(int newLevel)                   { check_safepoint(); flags.level = newLevel; }
 418 
 419   int   comp_level() const                        { return _comp_level; }
 420 
 421   int   version() const                           { return flags.version; }
 422   void  set_version(int v);
 423 
 424   // Non-perm oop support
 425   bool  on_scavenge_root_list() const                  { return (_scavenge_root_state & 1) != 0; }
 426  protected:
 427   enum { npl_on_list = 0x01, npl_marked = 0x10 };
 428   void  set_on_scavenge_root_list()                    { _scavenge_root_state = npl_on_list; }
 429   void  clear_on_scavenge_root_list()                  { _scavenge_root_state = 0; }
 430   // assertion-checking and pruning logic uses the bits of _scavenge_root_state
 431 #ifndef PRODUCT
 432   void  set_scavenge_root_marked()                     { _scavenge_root_state |= npl_marked; }
 433   void  clear_scavenge_root_marked()                   { _scavenge_root_state &= ~npl_marked; }
 434   bool  scavenge_root_not_marked()                     { return (_scavenge_root_state &~ npl_on_list) == 0; }
 435   // N.B. there is no positive marked query, and we only use the not_marked query for asserts.
 436 #endif //PRODUCT
 437   nmethod* scavenge_root_link() const                  { return _scavenge_root_link; }
 438   void     set_scavenge_root_link(nmethod *n)          { _scavenge_root_link = n; }
 439 
 440  public:
 441 
 442   // Sweeper support
 443   long  stack_traversal_mark()                    { return _stack_traversal_mark; }
 444   void  set_stack_traversal_mark(long l)          { _stack_traversal_mark = l; }
 445 
 446   // Exception cache support
 447   ExceptionCache* exception_cache() const         { return _exception_cache; }
 448   void set_exception_cache(ExceptionCache *ec)    { _exception_cache = ec; }
 449   address handler_for_exception_and_pc(Handle exception, address pc);
 450   void add_handler_for_exception_and_pc(Handle exception, address pc, address handler);
 451   void remove_from_exception_cache(ExceptionCache* ec);
 452 
 453   // implicit exceptions support
 454   address continuation_for_implicit_exception(address pc);
 455 
 456   // On-stack replacement support
 457   int   osr_entry_bci() const                     { assert(_entry_bci != InvocationEntryBci, "wrong kind of nmethod"); return _entry_bci; }
 458   address  osr_entry() const                      { assert(_entry_bci != InvocationEntryBci, "wrong kind of nmethod"); return _osr_entry_point; }
 459   void  invalidate_osr_method();
 460   nmethod* osr_link() const                       { return _osr_link; }
 461   void     set_osr_link(nmethod *n)               { _osr_link = n; }
 462 
 463   // tells whether frames described by this nmethod can be deoptimized
 464   // note: native wrappers cannot be deoptimized.
 465   bool can_be_deoptimized() const { return is_java_method(); }
 466 
 467   // Inline cache support
 468   void clear_inline_caches();
 469   void cleanup_inline_caches();
 470   bool inlinecache_check_contains(address addr) const {
 471     return (addr >= instructions_begin() && addr < verified_entry_point());
 472   }
 473 
 474   // unlink and deallocate this nmethod
 475   // Only NMethodSweeper class is expected to use this. NMethodSweeper is not
 476   // expected to use any other private methods/data in this class.
 477 
 478  protected:
 479   void flush();
 480 
 481  public:
 482   // If returning true, it is unsafe to remove this nmethod even though it is a zombie
 483   // nmethod, since the VM might have a reference to it. Should only be called from a  safepoint.
 484   bool is_locked_by_vm() const                    { return _lock_count >0; }
 485 
 486   // See comment at definition of _last_seen_on_stack
 487   void mark_as_seen_on_stack();
 488   bool can_not_entrant_be_converted();
 489 
 490   // Evolution support. We make old (discarded) compiled methods point to new methodOops.
 491   void set_method(methodOop method) { _method = method; }
 492 
 493   // GC support
 494   void do_unloading(BoolObjectClosure* is_alive, OopClosure* keep_alive,
 495                     bool unloading_occurred);
 496   bool can_unload(BoolObjectClosure* is_alive, OopClosure* keep_alive,
 497                   oop* root, bool unloading_occurred);
 498 
 499   void preserve_callee_argument_oops(frame fr, const RegisterMap *reg_map,
 500                                      OopClosure* f);
 501   virtual void oops_do(OopClosure* f) { oops_do(f, false); }
 502   void         oops_do(OopClosure* f, bool do_strong_roots_only);
 503   bool detect_scavenge_root_oops();
 504   void verify_scavenge_root_oops() PRODUCT_RETURN;
 505 
 506   bool test_set_oops_do_mark();
 507   static void oops_do_marking_prologue();
 508   static void oops_do_marking_epilogue();
 509   static bool oops_do_marking_is_active() { return _oops_do_mark_nmethods != NULL; }
 510   DEBUG_ONLY(bool test_oops_do_mark() { return _oops_do_mark_link != NULL; })
 511 
 512   // ScopeDesc for an instruction
 513   ScopeDesc* scope_desc_at(address pc);
 514 
 515  private:
 516   ScopeDesc* scope_desc_in(address begin, address end);
 517 
 518   address* orig_pc_addr(const frame* fr ) { return (address*) ((address)fr->unextended_sp() + _orig_pc_offset); }
 519 
 520   PcDesc* find_pc_desc_internal(address pc, bool approximate);
 521 
 522   PcDesc* find_pc_desc(address pc, bool approximate) {
 523     PcDesc* desc = _pc_desc_cache.last_pc_desc();
 524     if (desc != NULL && desc->pc_offset() == pc - instructions_begin()) {
 525       return desc;
 526     }
 527     return find_pc_desc_internal(pc, approximate);
 528   }
 529 
 530  public:
 531   // ScopeDesc retrieval operation
 532   PcDesc* pc_desc_at(address pc)   { return find_pc_desc(pc, false); }
 533   // pc_desc_near returns the first PcDesc at or after the givne pc.
 534   PcDesc* pc_desc_near(address pc) { return find_pc_desc(pc, true); }
 535 
 536  public:
 537   // copying of debugging information
 538   void copy_scopes_pcs(PcDesc* pcs, int count);
 539   void copy_scopes_data(address buffer, int size);
 540 
 541   // deopt
 542   // return true is the pc is one would expect if the frame is being deopted.
 543   bool is_deopt_pc(address pc);
 544   // Accessor/mutator for the original pc of a frame before a frame was deopted.
 545   address get_original_pc(const frame* fr) { return *orig_pc_addr(fr); }
 546   void    set_original_pc(const frame* fr, address pc) { *orig_pc_addr(fr) = pc; }
 547 
 548   // MethodHandle
 549   bool is_method_handle_return(address return_pc);
 550 
 551   // jvmti support:
 552   void post_compiled_method_load_event();
 553 
 554   // verify operations
 555   void verify();
 556   void verify_scopes();
 557   void verify_interrupt_point(address interrupt_point);
 558 
 559   // printing support
 560   void print()                          const;
 561   void print_code();
 562   void print_relocations()                        PRODUCT_RETURN;
 563   void print_pcs()                                PRODUCT_RETURN;
 564   void print_scopes()                             PRODUCT_RETURN;
 565   void print_dependencies()                       PRODUCT_RETURN;
 566   void print_value_on(outputStream* st) const     PRODUCT_RETURN;
 567   void print_calls(outputStream* st)              PRODUCT_RETURN;
 568   void print_handler_table()                      PRODUCT_RETURN;
 569   void print_nul_chk_table()                      PRODUCT_RETURN;
 570   void print_nmethod(bool print_code);
 571 
 572   void print_on(outputStream* st, const char* title) const;
 573 
 574   // Logging
 575   void log_identity(xmlStream* log) const;
 576   void log_new_nmethod() const;
 577   void log_state_change() const;
 578 
 579   // Prints a comment for one native instruction (reloc info, pc desc)
 580   void print_code_comment_on(outputStream* st, int column, address begin, address end);
 581   static void print_statistics()                  PRODUCT_RETURN;
 582 
 583   // Compiler task identification.  Note that all OSR methods
 584   // are numbered in an independent sequence if CICountOSR is true,
 585   // and native method wrappers are also numbered independently if
 586   // CICountNative is true.
 587   int  compile_id() const                         { return _compile_id; }
 588   const char* compile_kind() const;
 589 
 590   // For debugging
 591   // CompiledIC*    IC_at(char* p) const;
 592   // PrimitiveIC*   primitiveIC_at(char* p) const;
 593   oop embeddedOop_at(address p);
 594 
 595   // tells if any of this method's dependencies have been invalidated
 596   // (this is expensive!)
 597   bool check_all_dependencies();
 598 
 599   // tells if this compiled method is dependent on the given changes,
 600   // and the changes have invalidated it
 601   bool check_dependency_on(DepChange& changes);
 602 
 603   // Evolution support. Tells if this compiled method is dependent on any of
 604   // methods m() of class dependee, such that if m() in dependee is replaced,
 605   // this compiled method will have to be deoptimized.
 606   bool is_evol_dependent_on(klassOop dependee);
 607 
 608   // Fast breakpoint support. Tells if this compiled method is
 609   // dependent on the given method. Returns true if this nmethod
 610   // corresponds to the given method as well.
 611   bool is_dependent_on_method(methodOop dependee);
 612 
 613   // is it ok to patch at address?
 614   bool is_patchable_at(address instr_address);
 615 
 616   // UseBiasedLocking support
 617   ByteSize compiled_synchronized_native_basic_lock_owner_sp_offset() {
 618     return _compiled_synchronized_native_basic_lock_owner_sp_offset;
 619   }
 620   ByteSize compiled_synchronized_native_basic_lock_sp_offset() {
 621     return _compiled_synchronized_native_basic_lock_sp_offset;
 622   }
 623 
 624   // support for code generation
 625   static int verified_entry_point_offset()        { return offset_of(nmethod, _verified_entry_point); }
 626   static int osr_entry_point_offset()             { return offset_of(nmethod, _osr_entry_point); }
 627   static int entry_bci_offset()                   { return offset_of(nmethod, _entry_bci); }
 628 
 629 };
 630 
 631 // Locks an nmethod so its code will not get removed, even if it is a zombie/not_entrant method
 632 class nmethodLocker : public StackObj {
 633   nmethod* _nm;
 634 
 635   static void lock_nmethod(nmethod* nm);   // note: nm can be NULL
 636   static void unlock_nmethod(nmethod* nm); // (ditto)
 637 
 638  public:
 639   nmethodLocker(address pc); // derive nm from pc
 640   nmethodLocker(nmethod *nm) { _nm = nm; lock_nmethod(_nm); }
 641   nmethodLocker() { _nm = NULL; }
 642   ~nmethodLocker() { unlock_nmethod(_nm); }
 643 
 644   nmethod* code() { return _nm; }
 645   void set_code(nmethod* new_nm) {
 646     unlock_nmethod(_nm);   // note:  This works even if _nm==new_nm.
 647     _nm = new_nm;
 648     lock_nmethod(_nm);
 649   }
 650 };