/*

 * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#include "code/compiledMethod.hpp"

class DepChange;

class DirectiveSet;

class DebugInformationRecorder;

// nmethods (native methods) are the compiled code versions of Java methods.

//

// An nmethod contains:

//  - header                 (the nmethod structure)

//  [Relocation]

//  - relocation information

//  - constant part          (doubles, longs and floats used in nmethod)

//  - oop table

//  [Code]

//  - code body

//  - exception handler

//  - stub code

//  [Debugging information]

//  - oop array

//  - data array

//  - pcs

//  [Exception handler table]

//  - handler entry point array

//  [Implicit Null Pointer exception table]

//  - implicit null table array

class nmethod : public CompiledMethod {

  friend class VMStructs;

  friend class JVMCIVMStructs;

  friend class NMethodSweeper;

  friend class CodeCache;  // scavengable oops

 private:

  // Shared fields for all nmethod's

  int       _entry_bci;        // != InvocationEntryBci if this nmethod is an on-stack replacement method

  jmethodID _jmethod_id;       // Cache of method()->jmethod_id()

#if INCLUDE_JVMCI

  // A weak reference to an InstalledCode object associated with

  // this nmethod.

  jweak     _jvmci_installed_code;

  // A weak reference to a SpeculationLog object associated with

  // this nmethod.

  jweak     _speculation_log;

  // Determines whether this nmethod is unloaded when the

  // referent in _jvmci_installed_code is cleared. This

  // will be false if the referent is initialized to a

  // HotSpotNMethod object whose isDefault field is true.

  // That is, installed code other than a "default"

  // HotSpotNMethod causes nmethod unloading.

  // This field is ignored once _jvmci_installed_code is NULL.

  bool _jvmci_installed_code_triggers_invalidation;

#endif

  // To support simple linked-list chaining of nmethods:

  nmethod*  _osr_link;         // from InstanceKlass::osr_nmethods_head

  static nmethod* volatile _oops_do_mark_nmethods;

  nmethod*        volatile _oops_do_mark_link;

  // offsets for entry points

  address _entry_point;                      // entry point with class check

  address _verified_entry_point;             // entry point without class check

  address _osr_entry_point;                  // entry point for on stack replacement

  // Offsets for different nmethod parts

  int  _exception_offset;

  // Offset of the unwind handler if it exists

  int _unwind_handler_offset;

  int _consts_offset;

  int _stub_offset;

  int _oops_offset;                       // offset to where embedded oop table begins (inside data)

  int _metadata_offset;                   // embedded meta data table

  int _scopes_data_offset;

  int _scopes_pcs_offset;

  int _dependencies_offset;

  int _handler_table_offset;

  int _nul_chk_table_offset;

  int _nmethod_end_offset;

  int code_offset() const { return (address) code_begin() - header_begin(); }

  // location in frame (offset for sp) that deopt can store the original

  // pc during a deopt.

  int _orig_pc_offset;

  int _compile_id;                           // which compilation made this nmethod

  int _comp_level;                           // compilation level

  // protected by CodeCache_lock

  bool _has_flushed_dependencies;            // Used for maintenance of dependencies (CodeCache_lock)

  // used by jvmti to track if an unload event has been posted for this nmethod.

  bool _unload_reported;

  // Protected by Patching_lock

  volatile signed char _state;               // {not_installed, in_use, not_entrant, zombie, unloaded}

#ifdef ASSERT

  bool _oops_are_stale;  // indicates that it's no longer safe to access oops section

#endif

  jbyte _scavenge_root_state;

#if INCLUDE_RTM_OPT

  // RTM state at compile time. Used during deoptimization to decide

  // whether to restart collecting RTM locking abort statistic again.

  RTMState _rtm_state;

#endif

  // Nmethod Flushing lock. If non-zero, then the nmethod is not removed

  // and is not made into a zombie. However, once the nmethod is made into

  // a zombie, it will be locked one final time if CompiledMethodUnload

  // event processing needs to be done.

  volatile jint _lock_count;

  // not_entrant method removal. Each mark_sweep pass will update

  // this mark to current sweep invocation count if it is seen on the

  // stack.  An not_entrant method can be removed when there are no

  // more activations, i.e., when the _stack_traversal_mark is less than

  // current sweep traversal index.

  volatile long _stack_traversal_mark;

  // The _hotness_counter indicates the hotness of a method. The higher

  // the value the hotter the method. The hotness counter of a nmethod is

  // set to [(ReservedCodeCacheSize / (1024 * 1024)) * 2] each time the method

  // is active while stack scanning (mark_active_nmethods()). The hotness

  // counter is decreased (by 1) while sweeping.

  int _hotness_counter;

  // Local state used to keep track of whether unloading is happening or not

  volatile uint8_t _is_unloading_state;

  // These are used for compiled synchronized native methods to

  // locate the owner and stack slot for the BasicLock so that we can

  // properly revoke the bias of the owner if necessary. They are

  // needed because there is no debug information for compiled native

  // wrappers and the oop maps are insufficient to allow

  // frame::retrieve_receiver() to work. Currently they are expected

  // to be byte offsets from the Java stack pointer for maximum code

  // sharing between platforms. Note that currently biased locking

  // will never cause Class instances to be biased but this code

  // handles the static synchronized case as well.

  // JVMTI's GetLocalInstance() also uses these offsets to find the receiver

  // for non-static native wrapper frames.

  ByteSize _native_receiver_sp_offset;

  ByteSize _native_basic_lock_sp_offset;

  friend class nmethodLocker;

  // For native wrappers

  nmethod(Method* method,

          CompilerType type,

          int nmethod_size,

          int compile_id,

          CodeOffsets* offsets,

          CodeBuffer *code_buffer,

          int frame_size,

          ByteSize basic_lock_owner_sp_offset, /* synchronized natives only */

          ByteSize basic_lock_sp_offset,       /* synchronized natives only */

          OopMapSet* oop_maps);

  // Creation support

  nmethod(Method* method,

          CompilerType type,

          int nmethod_size,

          int compile_id,

          int entry_bci,

          CodeOffsets* offsets,

          int orig_pc_offset,

          DebugInformationRecorder *recorder,

          Dependencies* dependencies,

          CodeBuffer *code_buffer,

          int frame_size,

          OopMapSet* oop_maps,

          ExceptionHandlerTable* handler_table,

          ImplicitExceptionTable* nul_chk_table,

          AbstractCompiler* compiler,

          int comp_level

#if INCLUDE_JVMCI

          , jweak installed_code,

          jweak speculation_log

#endif

          );

  // helper methods

  void* operator new(size_t size, int nmethod_size, int comp_level) throw();

  const char* reloc_string_for(u_char* begin, u_char* end);

  // Returns true if this thread changed the state of the nmethod or

  // false if another thread performed the transition.

  bool make_not_entrant_or_zombie(int state);

  bool make_entrant() { Unimplemented(); return false; }

  void inc_decompile_count();

  // Inform external interfaces that a compiled method has been unloaded

  void post_compiled_method_unload();

  // Initailize fields to their default values

  void init_defaults();

  // Offsets

  int content_offset() const                  { return content_begin() - header_begin(); }

  int data_offset() const                     { return _data_offset; }

  address header_end() const                  { return (address)    header_begin() + header_size(); }

 public:

  // create nmethod with entry_bci

  static nmethod* new_nmethod(const methodHandle& method,

                              int compile_id,

                              int entry_bci,

                              CodeOffsets* offsets,

                              int orig_pc_offset,

                              DebugInformationRecorder* recorder,

                              Dependencies* dependencies,

                              CodeBuffer *code_buffer,

                              int frame_size,

                              OopMapSet* oop_maps,

                              ExceptionHandlerTable* handler_table,

                              ImplicitExceptionTable* nul_chk_table,

                              AbstractCompiler* compiler,

                              int comp_level

#if INCLUDE_JVMCI

                              , jweak installed_code = NULL,

                              jweak speculation_log = NULL

#endif

  );

  // Only used for unit tests.

  nmethod()

    : CompiledMethod(),

      _is_unloading_state(0),

      _native_receiver_sp_offset(in_ByteSize(-1)),

      _native_basic_lock_sp_offset(in_ByteSize(-1)) {}

  static nmethod* new_native_nmethod(const methodHandle& method,

                                     int compile_id,

                                     CodeBuffer *code_buffer,

                                     int vep_offset,

                                     int frame_complete,

                                     int frame_size,

                                     ByteSize receiver_sp_offset,

                                     ByteSize basic_lock_sp_offset,

                                     OopMapSet* oop_maps);

  // type info

  bool is_nmethod() const                         { return true; }

  bool is_osr_method() const                      { return _entry_bci != InvocationEntryBci; }

  // boundaries for different parts

  address consts_begin          () const          { return           header_begin() + _consts_offset        ; }

  address consts_end            () const          { return           code_begin()                           ; }

  address stub_begin            () const          { return           header_begin() + _stub_offset          ; }

  address stub_end              () const          { return           header_begin() + _oops_offset          ; }

  address exception_begin       () const          { return           header_begin() + _exception_offset     ; }

  address unwind_handler_begin  () const          { return _unwind_handler_offset != -1 ? (header_begin() + _unwind_handler_offset) : NULL; }

  oop*    oops_begin            () const          { return (oop*)   (header_begin() + _oops_offset)         ; }

  oop*    oops_end              () const          { return (oop*)   (header_begin() + _metadata_offset)     ; }

  Metadata** metadata_begin   () const            { return (Metadata**)  (header_begin() + _metadata_offset)     ; }

  Metadata** metadata_end     () const            { return (Metadata**)  _scopes_data_begin; }

  address scopes_data_end       () const          { return           header_begin() + _scopes_pcs_offset    ; }

  PcDesc* scopes_pcs_begin      () const          { return (PcDesc*)(header_begin() + _scopes_pcs_offset   ); }

  PcDesc* scopes_pcs_end        () const          { return (PcDesc*)(header_begin() + _dependencies_offset) ; }

  address dependencies_begin    () const          { return           header_begin() + _dependencies_offset  ; }

  address dependencies_end      () const          { return           header_begin() + _handler_table_offset ; }

  address handler_table_begin   () const          { return           header_begin() + _handler_table_offset ; }

  address handler_table_end     () const          { return           header_begin() + _nul_chk_table_offset ; }

  address nul_chk_table_begin   () const          { return           header_begin() + _nul_chk_table_offset ; }

  address nul_chk_table_end     () const          { return           header_begin() + _nmethod_end_offset   ; }

  // Sizes

  int oops_size         () const                  { return (address)  oops_end         () - (address)  oops_begin         (); }

  int metadata_size     () const                  { return (address)  metadata_end     () - (address)  metadata_begin     (); }

  int dependencies_size () const                  { return            dependencies_end () -            dependencies_begin (); }

  int     oops_count() const { assert(oops_size() % oopSize == 0, "");  return (oops_size() / oopSize) + 1; }

  int metadata_count() const { assert(metadata_size() % wordSize == 0, ""); return (metadata_size() / wordSize) + 1; }

  int total_size        () const;

  void dec_hotness_counter()        { _hotness_counter--; }

  void set_hotness_counter(int val) { _hotness_counter = val; }

  int  hotness_counter() const      { return _hotness_counter; }

  // Containment

  bool oops_contains         (oop*    addr) const { return oops_begin         () <= addr && addr < oops_end         (); }

  bool metadata_contains     (Metadata** addr) const   { return metadata_begin     () <= addr && addr < metadata_end     (); }

  bool scopes_data_contains  (address addr) const { return scopes_data_begin  () <= addr && addr < scopes_data_end  (); }

  bool scopes_pcs_contains   (PcDesc* addr) const { return scopes_pcs_begin   () <= addr && addr < scopes_pcs_end   (); }

  // entry points

  address entry_point() const                     { return _entry_point;             } // normal entry point

  address verified_entry_point() const            { return _verified_entry_point;    } // if klass is correct

  // flag accessing and manipulation

  bool  is_not_installed() const                  { return _state == not_installed; }

  bool  is_in_use() const                         { return _state <= in_use; }

  bool  is_alive() const                          { return _state < zombie; }

  bool  is_not_entrant() const                    { return _state == not_entrant; }

  bool  is_zombie() const                         { return _state == zombie; }

  bool  is_unloaded() const                       { return _state == unloaded; }

  void clear_unloading_state();

  virtual bool is_unloading();

  virtual void do_unloading(bool unloading_occurred);

#if INCLUDE_RTM_OPT

  // rtm state accessing and manipulating

  RTMState  rtm_state() const                     { return _rtm_state; }

  void set_rtm_state(RTMState state)              { _rtm_state = state; }

#endif

  void make_in_use()                              { _state = in_use; }

  // Make the nmethod non entrant. The nmethod will continue to be

  // alive.  It is used when an uncommon trap happens.  Returns true

  // if this thread changed the state of the nmethod or false if

  // another thread performed the transition.

  bool  make_not_entrant() {

    assert(!method()->is_method_handle_intrinsic(), "Cannot make MH intrinsic not entrant");

    return make_not_entrant_or_zombie(not_entrant);

  }

  bool  make_not_used()    { return make_not_entrant(); }

  bool  make_zombie()      { return make_not_entrant_or_zombie(zombie); }

  // used by jvmti to track if the unload event has been reported

  bool  unload_reported()                         { return _unload_reported; }

  void  set_unload_reported()                     { _unload_reported = true; }

  int get_state() const {

    return _state;

  }

  void  make_unloaded();

  bool has_dependencies()                         { return dependencies_size() != 0; }

  void flush_dependencies(bool delete_immediately);

  bool has_flushed_dependencies()                 { return _has_flushed_dependencies; }

  void set_has_flushed_dependencies()             {

    assert(!has_flushed_dependencies(), "should only happen once");

    _has_flushed_dependencies = 1;

  }

  int   comp_level() const                        { return _comp_level; }

  // Support for oops in scopes and relocs:

  // Note: index 0 is reserved for null.

  oop   oop_at(int index) const;

  oop*  oop_addr_at(int index) const {  // for GC

    // relocation indexes are biased by 1 (because 0 is reserved)

    assert(index > 0 && index <= oops_count(), "must be a valid non-zero index");

    assert(!_oops_are_stale, "oops are stale");

    return &oops_begin()[index - 1];

  }

  // Support for meta data in scopes and relocs:

  // Note: index 0 is reserved for null.

  Metadata*     metadata_at(int index) const      { return index == 0 ? NULL: *metadata_addr_at(index); }

  Metadata**  metadata_addr_at(int index) const {  // for GC

    // relocation indexes are biased by 1 (because 0 is reserved)

    assert(index > 0 && index <= metadata_count(), "must be a valid non-zero index");

    return &metadata_begin()[index - 1];

  }

  void copy_values(GrowableArray<jobject>* oops);

  void copy_values(GrowableArray<Metadata*>* metadata);

  // Relocation support

private:

  void fix_oop_relocations(address begin, address end, bool initialize_immediates);

  inline void initialize_immediate_oop(oop* dest, jobject handle);

public:

  void fix_oop_relocations(address begin, address end) { fix_oop_relocations(begin, end, false); }

  void fix_oop_relocations()                           { fix_oop_relocations(NULL, NULL, false); }

  // Scavengable oop support

  bool  on_scavenge_root_list() const                  { return (_scavenge_root_state & 1) != 0; }

 protected:

  enum { sl_on_list = 0x01, sl_marked = 0x10 };

  void  set_on_scavenge_root_list()                    { _scavenge_root_state = sl_on_list; }

  void  clear_on_scavenge_root_list()                  { _scavenge_root_state = 0; }

  // assertion-checking and pruning logic uses the bits of _scavenge_root_state

#ifndef PRODUCT

  void  set_scavenge_root_marked()                     { _scavenge_root_state |= sl_marked; }

  void  clear_scavenge_root_marked()                   { _scavenge_root_state &= ~sl_marked; }

  bool  scavenge_root_not_marked()                     { return (_scavenge_root_state &~ sl_on_list) == 0; }

  // N.B. there is no positive marked query, and we only use the not_marked query for asserts.

#endif //PRODUCT

  nmethod* scavenge_root_link() const                  { return _scavenge_root_link; }

  void     set_scavenge_root_link(nmethod *n)          { _scavenge_root_link = n; }

 public:

  // Sweeper support

  long  stack_traversal_mark()                    { return _stack_traversal_mark; }

  void  set_stack_traversal_mark(long l)          { _stack_traversal_mark = l; }

  // implicit exceptions support

  address continuation_for_implicit_exception(address pc);

  // On-stack replacement support

  int   osr_entry_bci() const                     { assert(is_osr_method(), "wrong kind of nmethod"); return _entry_bci; }

  address  osr_entry() const                      { assert(is_osr_method(), "wrong kind of nmethod"); return _osr_entry_point; }

  void  invalidate_osr_method();

  nmethod* osr_link() const                       { return _osr_link; }

  void     set_osr_link(nmethod *n)               { _osr_link = n; }

  // Verify calls to dead methods have been cleaned.

  void verify_clean_inline_caches();

  // unlink and deallocate this nmethod

  // Only NMethodSweeper class is expected to use this. NMethodSweeper is not

  // expected to use any other private methods/data in this class.

 protected:

  void flush();

 public:

  // When true is returned, it is unsafe to remove this nmethod even if

  // it is a zombie, since the VM or the ServiceThread might still be

  // using it.

  bool is_locked_by_vm() const                    { return _lock_count >0; }

  // See comment at definition of _last_seen_on_stack

  void mark_as_seen_on_stack();

  bool can_convert_to_zombie();

  // Evolution support. We make old (discarded) compiled methods point to new Method*s.

  void set_method(Method* method) { _method = method; }

#if INCLUDE_JVMCI

  // Gets the InstalledCode object associated with this nmethod

  // which may be NULL if this nmethod was not compiled by JVMCI

  // or the weak reference has been cleared.

  oop jvmci_installed_code();

  // Copies the value of the name field in the InstalledCode

  // object (if any) associated with this nmethod into buf.

  // Returns the value of buf if it was updated otherwise NULL.

  char* jvmci_installed_code_name(char* buf, size_t buflen) const;

  // Updates the state of the InstalledCode (if any) associated with

  // this nmethod based on the current value of _state.

  void maybe_invalidate_installed_code();

  // Deoptimizes the nmethod (if any) in the address field of a given

  // InstalledCode object. The address field is zeroed upon return.

  static void invalidate_installed_code(Handle installed_code, TRAPS);

  // Gets the SpeculationLog object associated with this nmethod

  // which may be NULL if this nmethod was not compiled by JVMCI

  // or the weak reference has been cleared.

  oop speculation_log();

 private:

  // Deletes the weak reference (if any) to the InstalledCode object

  // associated with this nmethod.

  void clear_jvmci_installed_code();

  // Deletes the weak reference (if any) to the SpeculationLog object