src/hotspot/share/oops/method.hpp - master - githubmirror/jdk11u-dev

src/hotspot/share/oops/method.hpp
1 199 строк47 KB
Jaroslav Bachorik
8313816: Accessing jmethodID might lead to spurious crashes
22 дек 2023, 14:18
22 дек 2023, 14:1853824e5
/*
 * Copyright (c) 1997, 2018, 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.
 *
 */

#ifndef SHARE_VM_OOPS_METHODOOP_HPP
#define SHARE_VM_OOPS_METHODOOP_HPP

#include "classfile/vmSymbols.hpp"
#include "code/compressedStream.hpp"
#include "compiler/compilerDefinitions.hpp"
#include "compiler/oopMap.hpp"
#include "interpreter/invocationCounter.hpp"
#include "oops/annotations.hpp"
#include "oops/constantPool.hpp"
#include "oops/methodCounters.hpp"
#include "oops/instanceKlass.hpp"
#include "oops/oop.hpp"
#include "oops/typeArrayOop.hpp"
#include "utilities/accessFlags.hpp"
#include "utilities/align.hpp"
#include "utilities/growableArray.hpp"
#include "utilities/macros.hpp"
#if INCLUDE_JFR
#include "jfr/support/jfrTraceIdExtension.hpp"
#endif


// A Method represents a Java method.
//
// Note that most applications load thousands of methods, so keeping the size of this
// class small has a big impact on footprint.
//
// Note that native_function and signature_handler have to be at fixed offsets
// (required by the interpreter)
//
//  Method embedded field layout (after declared fields):
//   [EMBEDDED native_function       (present only if native) ]
//   [EMBEDDED signature_handler     (present only if native) ]

class CheckedExceptionElement;
class LocalVariableTableElement;
class AdapterHandlerEntry;
class MethodData;
class MethodCounters;
class ConstMethod;
class InlineTableSizes;
class KlassSizeStats;
class CompiledMethod;

class Method : public Metadata {
 friend class VMStructs;
 friend class JVMCIVMStructs;
 private:
  // If you add a new field that points to any metaspace object, you
  // must add this field to Method::metaspace_pointers_do().
  ConstMethod*      _constMethod;                // Method read-only data.
  MethodData*       _method_data;
  MethodCounters*   _method_counters;
  AccessFlags       _access_flags;               // Access flags
  int               _vtable_index;               // vtable index of this method (see VtableIndexFlag)
                                                 // note: can have vtables with >2**16 elements (because of inheritance)
  u2                _intrinsic_id;               // vmSymbols::intrinsic_id (0 == _none)

  // Flags
  enum Flags {
    _caller_sensitive      = 1 << 0,
    _force_inline          = 1 << 1,
    _dont_inline           = 1 << 2,
    _hidden                = 1 << 3,
    _has_injected_profile  = 1 << 4,
    _running_emcp          = 1 << 5,
    _intrinsic_candidate   = 1 << 6,
    _reserved_stack_access = 1 << 7
  };
  mutable u2 _flags;

  JFR_ONLY(DEFINE_TRACE_FLAG;)

#ifndef PRODUCT
  int64_t _compiled_invocation_count;
#endif
  // Entry point for calling both from and to the interpreter.
  address _i2i_entry;           // All-args-on-stack calling convention
  // Entry point for calling from compiled code, to compiled code if it exists
  // or else the interpreter.
  volatile address _from_compiled_entry;        // Cache of: _code ? _code->entry_point() : _adapter->c2i_entry()
  // The entry point for calling both from and to compiled code is
  // "_code->entry_point()".  Because of tiered compilation and de-opt, this
  // field can come and go.  It can transition from NULL to not-null at any
  // time (whenever a compile completes).  It can transition from not-null to
  // NULL only at safepoints (because of a de-opt).
  CompiledMethod* volatile _code;                       // Points to the corresponding piece of native code
  volatile address           _from_interpreted_entry; // Cache of _code ? _adapter->i2c_entry() : _i2i_entry

#if INCLUDE_AOT && defined(TIERED)
  CompiledMethod* _aot_code;
#endif

  // Constructor
  Method(ConstMethod* xconst, AccessFlags access_flags);
 public:

  static Method* allocate(ClassLoaderData* loader_data,
                          int byte_code_size,
                          AccessFlags access_flags,
                          InlineTableSizes* sizes,
                          ConstMethod::MethodType method_type,
                          TRAPS);

  // CDS and vtbl checking can create an empty Method to get vtbl pointer.
  Method(){}

  bool is_method() const volatile { return true; }

  void restore_unshareable_info(TRAPS);

  // accessors for instance variables

  ConstMethod* constMethod() const             { return _constMethod; }
  void set_constMethod(ConstMethod* xconst)    { _constMethod = xconst; }


  static address make_adapters(const methodHandle& mh, TRAPS);
  address from_compiled_entry() const;
  address from_compiled_entry_no_trampoline() const;
  address from_interpreted_entry() const;

  // access flag
  AccessFlags access_flags() const               { return _access_flags;  }
  void set_access_flags(AccessFlags flags)       { _access_flags = flags; }

  // name
  Symbol* name() const                           { return constants()->symbol_at(name_index()); }
  int name_index() const                         { return constMethod()->name_index();         }
  void set_name_index(int index)                 { constMethod()->set_name_index(index);       }

  // signature
  Symbol* signature() const                      { return constants()->symbol_at(signature_index()); }
  int signature_index() const                    { return constMethod()->signature_index();         }
  void set_signature_index(int index)            { constMethod()->set_signature_index(index);       }

  // generics support
  Symbol* generic_signature() const              { int idx = generic_signature_index(); return ((idx != 0) ? constants()->symbol_at(idx) : (Symbol*)NULL); }
  int generic_signature_index() const            { return constMethod()->generic_signature_index(); }
  void set_generic_signature_index(int index)    { constMethod()->set_generic_signature_index(index); }

  // annotations support
  AnnotationArray* annotations() const           {
    return constMethod()->method_annotations();
  }
  AnnotationArray* parameter_annotations() const {
    return constMethod()->parameter_annotations();
  }
  AnnotationArray* annotation_default() const    {
    return constMethod()->default_annotations();
  }
  AnnotationArray* type_annotations() const      {
    return constMethod()->type_annotations();
  }

  // Helper routine: get klass name + "." + method name + signature as
  // C string, for the purpose of providing more useful
  // fatal error handling. The string is allocated in resource
  // area if a buffer is not provided by the caller.
  char* name_and_sig_as_C_string() const;
  char* name_and_sig_as_C_string(char* buf, int size) const;

  // Static routine in the situations we don't have a Method*
  static char* name_and_sig_as_C_string(Klass* klass, Symbol* method_name, Symbol* signature);
  static char* name_and_sig_as_C_string(Klass* klass, Symbol* method_name, Symbol* signature, char* buf, int size);

  // Get return type + klass name + "." + method name + ( parameters types )
  // as a C string or print it to an outputStream.
  // This is to be used to assemble strings passed to Java, so that
  // the text more resembles Java code. Used in exception messages.
  // Memory is allocated in the resource area; the caller needs
  // a ResourceMark.
  const char* external_name() const;
  void  print_external_name(outputStream *os) const;

  static const char* external_name(                  Klass* klass, Symbol* method_name, Symbol* signature);
  static void  print_external_name(outputStream *os, Klass* klass, Symbol* method_name, Symbol* signature);

  Bytecodes::Code java_code_at(int bci) const {
    return Bytecodes::java_code_at(this, bcp_from(bci));
  }
  Bytecodes::Code code_at(int bci) const {
    return Bytecodes::code_at(this, bcp_from(bci));
  }

  // JVMTI breakpoints
#if !INCLUDE_JVMTI
  Bytecodes::Code orig_bytecode_at(int bci) const {
    ShouldNotReachHere();
    return Bytecodes::_shouldnotreachhere;
  }
  void set_orig_bytecode_at(int bci, Bytecodes::Code code) {
    ShouldNotReachHere();
  };
  u2   number_of_breakpoints() const {return 0;}
#else // !INCLUDE_JVMTI
  Bytecodes::Code orig_bytecode_at(int bci) const;
  void set_orig_bytecode_at(int bci, Bytecodes::Code code);
  void set_breakpoint(int bci);
  void clear_breakpoint(int bci);
  void clear_all_breakpoints();
  // Tracking number of breakpoints, for fullspeed debugging.
  // Only mutated by VM thread.
  u2   number_of_breakpoints()             const {
    MethodCounters* mcs = method_counters();
    if (mcs == NULL) {
      return 0;
    } else {
      return mcs->number_of_breakpoints();
    }
  }
  void incr_number_of_breakpoints(TRAPS)         {
    MethodCounters* mcs = get_method_counters(CHECK);
    if (mcs != NULL) {
      mcs->incr_number_of_breakpoints();
    }
  }
  void decr_number_of_breakpoints(TRAPS)         {
    MethodCounters* mcs = get_method_counters(CHECK);
    if (mcs != NULL) {
      mcs->decr_number_of_breakpoints();
    }
  }
  // Initialization only
  void clear_number_of_breakpoints()             {
    MethodCounters* mcs = method_counters();
    if (mcs != NULL) {
      mcs->clear_number_of_breakpoints();
    }
  }
#endif // !INCLUDE_JVMTI

  // index into InstanceKlass methods() array
  // note: also used by jfr
  u2 method_idnum() const           { return constMethod()->method_idnum(); }
  void set_method_idnum(u2 idnum)   { constMethod()->set_method_idnum(idnum); }

  u2 orig_method_idnum() const           { return constMethod()->orig_method_idnum(); }
  void set_orig_method_idnum(u2 idnum)   { constMethod()->set_orig_method_idnum(idnum); }

  // code size
  int code_size() const                  { return constMethod()->code_size(); }

  // method size in words
  int method_size() const                { return sizeof(Method)/wordSize + ( is_native() ? 2 : 0 ); }

  // constant pool for Klass* holding this method
  ConstantPool* constants() const              { return constMethod()->constants(); }
  void set_constants(ConstantPool* c)          { constMethod()->set_constants(c); }

  // max stack
  // return original max stack size for method verification
  int  verifier_max_stack() const                { return constMethod()->max_stack(); }
  int           max_stack() const                { return constMethod()->max_stack() + extra_stack_entries(); }
  void      set_max_stack(int size)              {        constMethod()->set_max_stack(size); }

  // max locals
  int  max_locals() const                        { return constMethod()->max_locals(); }
  void set_max_locals(int size)                  { constMethod()->set_max_locals(size); }

  int highest_comp_level() const;
  void set_highest_comp_level(int level);
  int highest_osr_comp_level() const;
  void set_highest_osr_comp_level(int level);

#if COMPILER2_OR_JVMCI
  // Count of times method was exited via exception while interpreting
  void interpreter_throwout_increment(TRAPS) {
    MethodCounters* mcs = get_method_counters(CHECK);
    if (mcs != NULL) {
      mcs->interpreter_throwout_increment();
    }
  }
#endif

  int  interpreter_throwout_count() const        {
    MethodCounters* mcs = method_counters();
    if (mcs == NULL) {
      return 0;
    } else {
      return mcs->interpreter_throwout_count();
    }
  }

  // size of parameters
  int  size_of_parameters() const                { return constMethod()->size_of_parameters(); }
  void set_size_of_parameters(int size)          { constMethod()->set_size_of_parameters(size); }

  bool has_stackmap_table() const {
    return constMethod()->has_stackmap_table();
  }

  Array<u1>* stackmap_data() const {
    return constMethod()->stackmap_data();
  }

  void set_stackmap_data(Array<u1>* sd) {
    constMethod()->set_stackmap_data(sd);
  }

  // exception handler table
  bool has_exception_handler() const
                             { return constMethod()->has_exception_handler(); }
  int exception_table_length() const
                             { return constMethod()->exception_table_length(); }
  ExceptionTableElement* exception_table_start() const
                             { return constMethod()->exception_table_start(); }

  // Finds the first entry point bci of an exception handler for an
  // exception of klass ex_klass thrown at throw_bci. A value of NULL
  // for ex_klass indicates that the exception klass is not known; in
  // this case it matches any constraint class. Returns -1 if the
  // exception cannot be handled in this method. The handler
  // constraint classes are loaded if necessary. Note that this may
  // throw an exception if loading of the constraint classes causes
  // an IllegalAccessError (bugid 4307310) or an OutOfMemoryError.
  // If an exception is thrown, returns the bci of the
  // exception handler which caused the exception to be thrown, which
  // is needed for proper retries. See, for example,
  // InterpreterRuntime::exception_handler_for_exception.
  static int fast_exception_handler_bci_for(const methodHandle& mh, Klass* ex_klass, int throw_bci, TRAPS);

  // method data access
  MethodData* method_data() const              {
    return _method_data;
  }

  void set_method_data(MethodData* data);

  MethodCounters* method_counters() const {
    return _method_counters;
  }

  void clear_method_counters() {
    _method_counters = NULL;
  }

  bool init_method_counters(MethodCounters* counters);

#ifdef TIERED
  // We are reusing interpreter_invocation_count as a holder for the previous event count!
  // We can do that since interpreter_invocation_count is not used in tiered.
  int prev_event_count() const                   {
    if (method_counters() == NULL) {
      return 0;
    } else {
      return method_counters()->interpreter_invocation_count();
    }
  }
  void set_prev_event_count(int count) {
    MethodCounters* mcs = method_counters();
    if (mcs != NULL) {
      mcs->set_interpreter_invocation_count(count);
    }
  }
  jlong prev_time() const                        {
    MethodCounters* mcs = method_counters();
    return mcs == NULL ? 0 : mcs->prev_time();
  }
  void set_prev_time(jlong time) {
    MethodCounters* mcs = method_counters();
    if (mcs != NULL) {
      mcs->set_prev_time(time);
    }
  }
  float rate() const                             {
    MethodCounters* mcs = method_counters();
    return mcs == NULL ? 0 : mcs->rate();
  }
  void set_rate(float rate) {
    MethodCounters* mcs = method_counters();
    if (mcs != NULL) {
      mcs->set_rate(rate);
    }
  }

#if INCLUDE_AOT
  void set_aot_code(CompiledMethod* aot_code) {
    _aot_code = aot_code;
  }

  CompiledMethod* aot_code() const {
    return _aot_code;
  }
#else
  CompiledMethod* aot_code() const { return NULL; }
#endif // INCLUDE_AOT
#endif // TIERED

  int nmethod_age() const {
    if (method_counters() == NULL) {
      return INT_MAX;
    } else {
      return method_counters()->nmethod_age();
    }
  }

  int invocation_count();
  int backedge_count();

  bool was_executed_more_than(int n);
  bool was_never_executed()                      { return !was_executed_more_than(0); }

  static void build_interpreter_method_data(const methodHandle& method, TRAPS);

  static MethodCounters* build_method_counters(Method* m, TRAPS);

  int interpreter_invocation_count() {
    if (TieredCompilation) {
      return invocation_count();
    } else {
      MethodCounters* mcs = method_counters();
      return (mcs == NULL) ? 0 : mcs->interpreter_invocation_count();
    }
  }
#if COMPILER2_OR_JVMCI
  int increment_interpreter_invocation_count(TRAPS) {
    if (TieredCompilation) ShouldNotReachHere();
    MethodCounters* mcs = get_method_counters(CHECK_0);
    return (mcs == NULL) ? 0 : mcs->increment_interpreter_invocation_count();
  }
#endif

#ifndef PRODUCT
  int64_t  compiled_invocation_count() const    { return _compiled_invocation_count;}
  void set_compiled_invocation_count(int count) { _compiled_invocation_count = (int64_t)count; }
 #else
   // for PrintMethodData in a product build
  int64_t  compiled_invocation_count() const    { return 0; }
#endif // not PRODUCT

  // Clear (non-shared space) pointers which could not be relevant
  // if this (shared) method were mapped into another JVM.
  void remove_unshareable_info();

  // nmethod/verified compiler entry
  address verified_code_entry();
  bool check_code() const;      // Not inline to avoid circular ref
  CompiledMethod* volatile code() const;
  void clear_code(bool acquire_lock = true);    // Clear out any compiled code
  static void set_code(const methodHandle& mh, CompiledMethod* code);
  void set_adapter_entry(AdapterHandlerEntry* adapter) {
    constMethod()->set_adapter_entry(adapter);
  }
  void update_adapter_trampoline(AdapterHandlerEntry* adapter) {
    constMethod()->update_adapter_trampoline(adapter);
  }

  address get_i2c_entry();
  address get_c2i_entry();
  address get_c2i_unverified_entry();
  AdapterHandlerEntry* adapter() const {
    return constMethod()->adapter();
  }
  // setup entry points
  void link_method(const methodHandle& method, TRAPS);
  // clear entry points. Used by sharing code during dump time
  void unlink_method() NOT_CDS_RETURN;

  virtual void metaspace_pointers_do(MetaspaceClosure* iter);
  virtual MetaspaceObj::Type type() const { return MethodType; }

  // vtable index
  enum VtableIndexFlag {
    // Valid vtable indexes are non-negative (>= 0).
    // These few negative values are used as sentinels.
    itable_index_max        = -10, // first itable index, growing downward
    pending_itable_index    = -9,  // itable index will be assigned
    invalid_vtable_index    = -4,  // distinct from any valid vtable index
    garbage_vtable_index    = -3,  // not yet linked; no vtable layout yet
    nonvirtual_vtable_index = -2   // there is no need for vtable dispatch
    // 6330203 Note:  Do not use -1, which was overloaded with many meanings.
  };
  DEBUG_ONLY(bool valid_vtable_index() const     { return _vtable_index >= nonvirtual_vtable_index; })
  bool has_vtable_index() const                  { return _vtable_index >= 0; }
  int  vtable_index() const                      { return _vtable_index; }
  void set_vtable_index(int index);
  DEBUG_ONLY(bool valid_itable_index() const     { return _vtable_index <= pending_itable_index; })
  bool has_itable_index() const                  { return _vtable_index <= itable_index_max; }
  int  itable_index() const                      { assert(valid_itable_index(), "");
                                                   return itable_index_max - _vtable_index; }
  void set_itable_index(int index);

  // interpreter entry
  address interpreter_entry() const              { return _i2i_entry; }
  // Only used when first initialize so we can set _i2i_entry and _from_interpreted_entry
  void set_interpreter_entry(address entry) {
    assert(!is_shared(), "shared method's interpreter entry should not be changed at run time");
    if (_i2i_entry != entry) {
      _i2i_entry = entry;
    }
    if (_from_interpreted_entry != entry) {
      _from_interpreted_entry = entry;
    }
  }

  // native function (used for native methods only)
  enum {
    native_bind_event_is_interesting = true
  };
  address native_function() const                { return *(native_function_addr()); }

  // Must specify a real function (not NULL).
  // Use clear_native_function() to unregister.
  void set_native_function(address function, bool post_event_flag);
  bool has_native_function() const;
  void clear_native_function();

  // signature handler (used for native methods only)
  address signature_handler() const              { return *(signature_handler_addr()); }
  void set_signature_handler(address handler);

  // Interpreter oopmap support
  void mask_for(int bci, InterpreterOopMap* mask);

  // operations on invocation counter
  void print_invocation_count();

  // byte codes
  void    set_code(address code)      { return constMethod()->set_code(code); }
  address code_base() const           { return constMethod()->code_base(); }
  bool    contains(address bcp) const { return constMethod()->contains(bcp); }

  // prints byte codes
  void print_codes() const            { print_codes_on(tty); }
  void print_codes_on(outputStream* st) const;
  void print_codes_on(int from, int to, outputStream* st) const;

  // method parameters
  bool has_method_parameters() const
                         { return constMethod()->has_method_parameters(); }
  int method_parameters_length() const
                         { return constMethod()->method_parameters_length(); }
  MethodParametersElement* method_parameters_start() const
                          { return constMethod()->method_parameters_start(); }

  // checked exceptions
  int checked_exceptions_length() const
                         { return constMethod()->checked_exceptions_length(); }
  CheckedExceptionElement* checked_exceptions_start() const
                          { return constMethod()->checked_exceptions_start(); }

  // localvariable table
  bool has_localvariable_table() const
                          { return constMethod()->has_localvariable_table(); }
  int localvariable_table_length() const
                        { return constMethod()->localvariable_table_length(); }
  LocalVariableTableElement* localvariable_table_start() const
                         { return constMethod()->localvariable_table_start(); }

  bool has_linenumber_table() const
                              { return constMethod()->has_linenumber_table(); }
  u_char* compressed_linenumber_table() const
                       { return constMethod()->compressed_linenumber_table(); }

  // method holder (the Klass* holding this method)
  InstanceKlass* method_holder() const         { return constants()->pool_holder(); }

  void compute_size_of_parameters(Thread *thread); // word size of parameters (receiver if any + arguments)
  Symbol* klass_name() const;                    // returns the name of the method holder
  BasicType result_type() const;                 // type of the method result
  bool is_returning_oop() const                  { BasicType r = result_type(); return (r == T_OBJECT || r == T_ARRAY); }
  bool is_returning_fp() const                   { BasicType r = result_type(); return (r == T_FLOAT || r == T_DOUBLE); }

  // Checked exceptions thrown by this method (resolved to mirrors)
  objArrayHandle resolved_checked_exceptions(TRAPS) { return resolved_checked_exceptions_impl(this, THREAD); }

  // Access flags
  bool is_public() const                         { return access_flags().is_public();      }
  bool is_private() const                        { return access_flags().is_private();     }
  bool is_protected() const                      { return access_flags().is_protected();   }
  bool is_package_private() const                { return !is_public() && !is_private() && !is_protected(); }
  bool is_static() const                         { return access_flags().is_static();      }
  bool is_final() const                          { return access_flags().is_final();       }
  bool is_synchronized() const                   { return access_flags().is_synchronized();}
  bool is_native() const                         { return access_flags().is_native();      }
  bool is_abstract() const                       { return access_flags().is_abstract();    }
  bool is_strict() const                         { return access_flags().is_strict();      }
  bool is_synthetic() const                      { return access_flags().is_synthetic();   }

  // returns true if contains only return operation
  bool is_empty_method() const;

  // returns true if this is a vanilla constructor
  bool is_vanilla_constructor() const;

  // checks method and its method holder
  bool is_final_method() const;
  bool is_final_method(AccessFlags class_access_flags) const;
  // interface method declared with 'default' - excludes private interface methods
  bool is_default_method() const;

  // true if method needs no dynamic dispatch (final and/or no vtable entry)
  bool can_be_statically_bound() const;
  bool can_be_statically_bound(AccessFlags class_access_flags) const;

  // returns true if the method has any backward branches.
  bool has_loops() {
    return access_flags().loops_flag_init() ? access_flags().has_loops() : compute_has_loops_flag();
  };

  bool compute_has_loops_flag();

  bool has_jsrs() {
    return access_flags().has_jsrs();
  };
  void set_has_jsrs() {
    _access_flags.set_has_jsrs();
  }

  // returns true if the method has any monitors.
  bool has_monitors() const                      { return is_synchronized() || access_flags().has_monitor_bytecodes(); }
  bool has_monitor_bytecodes() const             { return access_flags().has_monitor_bytecodes(); }

  void set_has_monitor_bytecodes()               { _access_flags.set_has_monitor_bytecodes(); }

  // monitor matching. This returns a conservative estimate of whether the monitorenter/monitorexit bytecodes
  // propererly nest in the method. It might return false, even though they actually nest properly, since the info.
  // has not been computed yet.
  bool guaranteed_monitor_matching() const       { return access_flags().is_monitor_matching(); }
  void set_guaranteed_monitor_matching()         { _access_flags.set_monitor_matching(); }

  // returns true if the method is an accessor function (setter/getter).
  bool is_accessor() const;

  // returns true if the method is a getter
  bool is_getter() const;

  // returns true if the method is a setter
  bool is_setter() const;

  // returns true if the method does nothing but return a constant of primitive type
  bool is_constant_getter() const;

  // returns true if the method is an initializer (<init> or <clinit>).
  bool is_initializer() const;

  // returns true if the method is static OR if the classfile version < 51
  bool has_valid_initializer_flags() const;

  // returns true if the method name is <clinit> and the method has
  // valid static initializer flags.
  bool is_static_initializer() const;

  // returns true if the method name is <init>
  bool is_object_initializer() const;

  // compiled code support
  // NOTE: code() is inherently racy as deopt can be clearing code
  // simultaneously. Use with caution.
  bool has_compiled_code() const;

#ifdef TIERED
  bool has_aot_code() const                      { return aot_code() != NULL; }
#endif

  // sizing
  static int header_size()                       {
    return align_up((int)sizeof(Method), wordSize) / wordSize;
  }
  static int size(bool is_native);
  int size() const                               { return method_size(); }
#if INCLUDE_SERVICES
  void collect_statistics(KlassSizeStats *sz) const;
#endif
  void log_touched(TRAPS);
  static void print_touched_methods(outputStream* out);

  // interpreter support
  static ByteSize const_offset()                 { return byte_offset_of(Method, _constMethod       ); }
  static ByteSize access_flags_offset()          { return byte_offset_of(Method, _access_flags      ); }
  static ByteSize from_compiled_offset()         { return byte_offset_of(Method, _from_compiled_entry); }
  static ByteSize code_offset()                  { return byte_offset_of(Method, _code); }
  static ByteSize method_data_offset()           {
    return byte_offset_of(Method, _method_data);
  }
  static ByteSize method_counters_offset()       {
    return byte_offset_of(Method, _method_counters);
  }
#ifndef PRODUCT
  static ByteSize compiled_invocation_counter_offset() { return byte_offset_of(Method, _compiled_invocation_count); }
#endif // not PRODUCT
  static ByteSize native_function_offset()       { return in_ByteSize(sizeof(Method));                 }
  static ByteSize from_interpreted_offset()      { return byte_offset_of(Method, _from_interpreted_entry ); }
  static ByteSize interpreter_entry_offset()     { return byte_offset_of(Method, _i2i_entry ); }
  static ByteSize signature_handler_offset()     { return in_ByteSize(sizeof(Method) + wordSize);      }
  static ByteSize itable_index_offset()          { return byte_offset_of(Method, _vtable_index ); }

  // for code generation
  static int method_data_offset_in_bytes()       { return offset_of(Method, _method_data); }
  static int intrinsic_id_offset_in_bytes()      { return offset_of(Method, _intrinsic_id); }
  static int intrinsic_id_size_in_bytes()        { return sizeof(u2); }

  // Static methods that are used to implement member methods where an exposed this pointer
  // is needed due to possible GCs
  static objArrayHandle resolved_checked_exceptions_impl(Method* method, TRAPS);

  // Returns the byte code index from the byte code pointer
  int     bci_from(address bcp) const;
  address bcp_from(int bci) const;
  address bcp_from(address bcp) const;
  int validate_bci_from_bcp(address bcp) const;
  int validate_bci(int bci) const;

  // Returns the line number for a bci if debugging information for the method is prowided,
  // -1 is returned otherwise.
  int line_number_from_bci(int bci) const;

  // Reflection support
  bool is_overridden_in(Klass* k) const;

  // Stack walking support
  bool is_ignored_by_security_stack_walk() const;

  // JSR 292 support
  bool is_method_handle_intrinsic() const;          // MethodHandles::is_signature_polymorphic_intrinsic(intrinsic_id)
  bool is_compiled_lambda_form() const;             // intrinsic_id() == vmIntrinsics::_compiledLambdaForm
  bool has_member_arg() const;                      // intrinsic_id() == vmIntrinsics::_linkToSpecial, etc.
  static methodHandle make_method_handle_intrinsic(vmIntrinsics::ID iid, // _invokeBasic, _linkToVirtual
                                                   Symbol* signature, //anything at all
                                                   TRAPS);
  static Klass* check_non_bcp_klass(Klass* klass);

  enum {
    // How many extra stack entries for invokedynamic
    extra_stack_entries_for_jsr292 = 1
  };

  // this operates only on invoke methods:
  // presize interpreter frames for extra interpreter stack entries, if needed
  // Account for the extra appendix argument for invokehandle/invokedynamic
  static int extra_stack_entries() { return extra_stack_entries_for_jsr292; }
  static int extra_stack_words();  // = extra_stack_entries() * Interpreter::stackElementSize

  // RedefineClasses() support:
  bool is_old() const                               { return access_flags().is_old(); }
  void set_is_old()                                 { _access_flags.set_is_old(); }
  bool is_obsolete() const                          { return access_flags().is_obsolete(); }
  void set_is_obsolete()                            { _access_flags.set_is_obsolete(); }
  bool is_deleted() const                           { return access_flags().is_deleted(); }
  void set_is_deleted()                             { _access_flags.set_is_deleted(); }

  bool is_running_emcp() const {
    // EMCP methods are old but not obsolete or deleted. Equivalent
    // Modulo Constant Pool means the method is equivalent except
    // the constant pool and instructions that access the constant
    // pool might be different.
    // If a breakpoint is set in a redefined method, its EMCP methods that are
    // still running must have a breakpoint also.
    return (_flags & _running_emcp) != 0;
  }

  void set_running_emcp(bool x) {
    _flags = x ? (_flags | _running_emcp) : (_flags & ~_running_emcp);
  }

  bool on_stack() const                             { return access_flags().on_stack(); }
  void set_on_stack(const bool value);

  // see the definition in Method*.cpp for the gory details
  bool should_not_be_cached() const;

  // JVMTI Native method prefixing support:
  bool is_prefixed_native() const                   { return access_flags().is_prefixed_native(); }
  void set_is_prefixed_native()                     { _access_flags.set_is_prefixed_native(); }

  // Rewriting support
  static methodHandle clone_with_new_data(const methodHandle& m, u_char* new_code, int new_code_length,
                                          u_char* new_compressed_linenumber_table, int new_compressed_linenumber_size, TRAPS);

  // jmethodID handling
  // Because the useful life-span of a jmethodID cannot be determined,
  // once created they are never reclaimed.  The methods to which they refer,
  // however, can be GC'ed away if the class is unloaded or if the method is
  // made obsolete or deleted -- in these cases, the jmethodID
  // refers to NULL (as is the case for any weak reference).
  static jmethodID make_jmethod_id(ClassLoaderData* loader_data, Method* mh);
  static void destroy_jmethod_id(ClassLoaderData* loader_data, jmethodID mid);

  // Ensure there is enough capacity in the internal tracking data
  // structures to hold the number of jmethodIDs you plan to generate.
  // This saves substantial time doing allocations.
  static void ensure_jmethod_ids(ClassLoaderData* loader_data, int capacity);

  // Use resolve_jmethod_id() in situations where the caller is expected
  // to provide a valid jmethodID; the only sanity checks are in asserts;
  // result guaranteed not to be NULL.
  inline static Method* resolve_jmethod_id(jmethodID mid) {
    assert(mid != NULL, "JNI method id should not be null");
    return *((Method**)mid);
  }

  // Use checked_resolve_jmethod_id() in situations where the caller
  // should provide a valid jmethodID, but might not. NULL is returned
  // when the jmethodID does not refer to a valid method.
  static Method* checked_resolve_jmethod_id(jmethodID mid);

  static void change_method_associated_with_jmethod_id(jmethodID old_jmid_ptr, Method* new_method);
  static bool is_method_id(jmethodID mid);

  // Clear methods
  static void clear_jmethod_ids(ClassLoaderData* loader_data);
  void clear_jmethod_id();
  static void print_jmethod_ids(const ClassLoaderData* loader_data, outputStream* out) PRODUCT_RETURN;

  // Get this method's jmethodID -- allocate if it doesn't exist
  jmethodID jmethod_id()                            { return method_holder()->get_jmethod_id(this); }

  // Lookup the jmethodID for this method.  Return NULL if not found.
  // NOTE that this function can be called from a signal handler
  // (see AsyncGetCallTrace support for Forte Analyzer) and this
  // needs to be async-safe. No allocation should be done and
  // so handles are not used to avoid deadlock.
  jmethodID find_jmethod_id_or_null()               { return method_holder()->jmethod_id_or_null(this); }

  // Support for inlining of intrinsic methods
  vmIntrinsics::ID intrinsic_id() const          { return (vmIntrinsics::ID) _intrinsic_id;           }
  void     set_intrinsic_id(vmIntrinsics::ID id) {                           _intrinsic_id = (u2) id; }

  // Helper routines for intrinsic_id() and vmIntrinsics::method().
  void init_intrinsic_id();     // updates from _none if a match
  static vmSymbols::SID klass_id_for_intrinsics(const Klass* holder);

  bool caller_sensitive() {
    return (_flags & _caller_sensitive) != 0;
  }
  void set_caller_sensitive(bool x) {
    _flags = x ? (_flags | _caller_sensitive) : (_flags & ~_caller_sensitive);
  }

  bool force_inline() {
    return (_flags & _force_inline) != 0;
  }
  void set_force_inline(bool x) {
    _flags = x ? (_flags | _force_inline) : (_flags & ~_force_inline);
  }

  bool dont_inline() {
    return (_flags & _dont_inline) != 0;
  }
  void set_dont_inline(bool x) {
    _flags = x ? (_flags | _dont_inline) : (_flags & ~_dont_inline);
  }

  bool is_hidden() {
    return (_flags & _hidden) != 0;
  }
  void set_hidden(bool x) {
    _flags = x ? (_flags | _hidden) : (_flags & ~_hidden);
  }

  bool intrinsic_candidate() {
    return (_flags & _intrinsic_candidate) != 0;
  }
  void set_intrinsic_candidate(bool x) {
    _flags = x ? (_flags | _intrinsic_candidate) : (_flags & ~_intrinsic_candidate);
  }

  bool has_injected_profile() {
    return (_flags & _has_injected_profile) != 0;
  }
  void set_has_injected_profile(bool x) {
    _flags = x ? (_flags | _has_injected_profile) : (_flags & ~_has_injected_profile);
  }

  bool has_reserved_stack_access() {
    return (_flags & _reserved_stack_access) != 0;
  }

  void set_has_reserved_stack_access(bool x) {
    _flags = x ? (_flags | _reserved_stack_access) : (_flags & ~_reserved_stack_access);
  }

  JFR_ONLY(DEFINE_TRACE_FLAG_ACCESSOR;)

  ConstMethod::MethodType method_type() const {
      return _constMethod->method_type();
  }
  bool is_overpass() const { return method_type() == ConstMethod::OVERPASS; }

  // On-stack replacement support
  bool has_osr_nmethod(int level, bool match_level) {
   return method_holder()->lookup_osr_nmethod(this, InvocationEntryBci, level, match_level) != NULL;
  }

  int mark_osr_nmethods() {
    return method_holder()->mark_osr_nmethods(this);
  }

  nmethod* lookup_osr_nmethod_for(int bci, int level, bool match_level) {
    return method_holder()->lookup_osr_nmethod(this, bci, level, match_level);
  }

  // Find if klass for method is loaded
  bool is_klass_loaded_by_klass_index(int klass_index) const;
  bool is_klass_loaded(int refinfo_index, bool must_be_resolved = false) const;

  // Indicates whether compilation failed earlier for this method, or
  // whether it is not compilable for another reason like having a
  // breakpoint set in it.
  bool  is_not_compilable(int comp_level = CompLevel_any) const;
  void set_not_compilable(int comp_level = CompLevel_all, bool report = true, const char* reason = NULL);
  void set_not_compilable_quietly(int comp_level = CompLevel_all) {
    set_not_compilable(comp_level, false);
  }
  bool  is_not_osr_compilable(int comp_level = CompLevel_any) const;
  void set_not_osr_compilable(int comp_level = CompLevel_all, bool report = true, const char* reason = NULL);
  void set_not_osr_compilable_quietly(int comp_level = CompLevel_all) {
    set_not_osr_compilable(comp_level, false);
  }
  bool is_always_compilable() const;

 private:
  void print_made_not_compilable(int comp_level, bool is_osr, bool report, const char* reason);

 public:
  MethodCounters* get_method_counters(TRAPS) {
    if (_method_counters == NULL) {
      build_method_counters(this, CHECK_AND_CLEAR_NULL);
    }
    return _method_counters;
  }

  bool   is_not_c1_compilable() const         { return access_flags().is_not_c1_compilable();  }
  void  set_not_c1_compilable()               {       _access_flags.set_not_c1_compilable();   }
  void clear_not_c1_compilable()              {       _access_flags.clear_not_c1_compilable(); }
  bool   is_not_c2_compilable() const         { return access_flags().is_not_c2_compilable();  }
  void  set_not_c2_compilable()               {       _access_flags.set_not_c2_compilable();   }
  void clear_not_c2_compilable()              {       _access_flags.clear_not_c2_compilable(); }

  bool    is_not_c1_osr_compilable() const    { return is_not_c1_compilable(); }  // don't waste an accessFlags bit
  void   set_not_c1_osr_compilable()          {       set_not_c1_compilable(); }  // don't waste an accessFlags bit
  void clear_not_c1_osr_compilable()          {     clear_not_c1_compilable(); }  // don't waste an accessFlags bit
  bool   is_not_c2_osr_compilable() const     { return access_flags().is_not_c2_osr_compilable();  }
  void  set_not_c2_osr_compilable()           {       _access_flags.set_not_c2_osr_compilable();   }
  void clear_not_c2_osr_compilable()          {       _access_flags.clear_not_c2_osr_compilable(); }

  // Background compilation support
  bool queued_for_compilation() const  { return access_flags().queued_for_compilation(); }
  void set_queued_for_compilation()    { _access_flags.set_queued_for_compilation();     }
  void clear_queued_for_compilation()  { _access_flags.clear_queued_for_compilation();   }

  // Resolve all classes in signature, return 'true' if successful
  static bool load_signature_classes(const methodHandle& m, TRAPS);

  // Return if true if not all classes references in signature, including return type, has been loaded
  static bool has_unloaded_classes_in_signature(const methodHandle& m, TRAPS);

  // Printing
  void print_short_name(outputStream* st = tty); // prints as klassname::methodname; Exposed so field engineers can debug VM
#if INCLUDE_JVMTI
  void print_name(outputStream* st = tty); // prints as "virtual void foo(int)"; exposed for TraceRedefineClasses
#else
  void print_name(outputStream* st = tty)        PRODUCT_RETURN; // prints as "virtual void foo(int)"
#endif

  // Helper routine used for method sorting
  static void sort_methods(Array<Method*>* methods, bool idempotent = false, bool set_idnums = true);

  // Deallocation function for redefine classes or if an error occurs
  void deallocate_contents(ClassLoaderData* loader_data);

  Method* get_new_method() const {
    InstanceKlass* holder = method_holder();
    Method* new_method = holder->method_with_idnum(orig_method_idnum());

    assert(new_method != NULL, "method_with_idnum() should not be null");
    assert(this != new_method, "sanity check");
    return new_method;
  }

  // Printing
#ifndef PRODUCT
  void print_on(outputStream* st) const;
#endif
  void print_value_on(outputStream* st) const;
  void print_linkage_flags(outputStream* st) PRODUCT_RETURN;

  const char* internal_name() const { return "{method}"; }

  // Check for valid method pointer
  static bool has_method_vptr(const void* ptr);
  static bool is_valid_method(const Method* m);

  // Verify
  void verify() { verify_on(tty); }
  void verify_on(outputStream* st);

 private:

  // Inlined elements
  address* native_function_addr() const          { assert(is_native(), "must be native"); return (address*) (this+1); }
  address* signature_handler_addr() const        { return native_function_addr() + 1; }
};


// Utility class for compressing line number tables

class CompressedLineNumberWriteStream: public CompressedWriteStream {
 private:
  int _bci;
  int _line;
 public:
  // Constructor
  CompressedLineNumberWriteStream(int initial_size) : CompressedWriteStream(initial_size), _bci(0), _line(0) {}
  CompressedLineNumberWriteStream(u_char* buffer, int initial_size) : CompressedWriteStream(buffer, initial_size), _bci(0), _line(0) {}

  // Write (bci, line number) pair to stream
  void write_pair_regular(int bci_delta, int line_delta);

  inline void write_pair_inline(int bci, int line) {
    int bci_delta = bci - _bci;
    int line_delta = line - _line;
    _bci = bci;
    _line = line;
    // Skip (0,0) deltas - they do not add information and conflict with terminator.
    if (bci_delta == 0 && line_delta == 0) return;
    // Check if bci is 5-bit and line number 3-bit unsigned.
    if (((bci_delta & ~0x1F) == 0) && ((line_delta & ~0x7) == 0)) {
      // Compress into single byte.
      jubyte value = ((jubyte) bci_delta << 3) | (jubyte) line_delta;
      // Check that value doesn't match escape character.
      if (value != 0xFF) {
        write_byte(value);
        return;
      }
    }
    write_pair_regular(bci_delta, line_delta);
  }

// Windows AMD64 + Apr 2005 PSDK with /O2 generates bad code for write_pair.
// Disabling optimization doesn't work for methods in header files
// so we force it to call through the non-optimized version in the .cpp.
// It's gross, but it's the only way we can ensure that all callers are
// fixed.  _MSC_VER is defined by the windows compiler
#if defined(_M_AMD64) && _MSC_VER >= 1400
  void write_pair(int bci, int line);
#else
  void write_pair(int bci, int line) { write_pair_inline(bci, line); }
#endif

  // Write end-of-stream marker
  void write_terminator()                        { write_byte(0); }
};


// Utility class for decompressing line number tables

class CompressedLineNumberReadStream: public CompressedReadStream {
 private:
  int _bci;
  int _line;
 public:
  // Constructor
  CompressedLineNumberReadStream(u_char* buffer);
  // Read (bci, line number) pair from stream. Returns false at end-of-stream.
  bool read_pair();
  // Accessing bci and line number (after calling read_pair)
  int bci() const                               { return _bci; }
  int line() const                              { return _line; }
};


#if INCLUDE_JVMTI

/// Fast Breakpoints.

// If this structure gets more complicated (because bpts get numerous),
// move it into its own header.

// There is presently no provision for concurrent access
// to breakpoint lists, which is only OK for JVMTI because
// breakpoints are written only at safepoints, and are read
// concurrently only outside of safepoints.

class BreakpointInfo : public CHeapObj<mtClass> {
  friend class VMStructs;
 private:
  Bytecodes::Code  _orig_bytecode;
  int              _bci;
  u2               _name_index;       // of method
  u2               _signature_index;  // of method
  BreakpointInfo*  _next;             // simple storage allocation

 public:
  BreakpointInfo(Method* m, int bci);

  // accessors
  Bytecodes::Code orig_bytecode()                     { return _orig_bytecode; }
  void        set_orig_bytecode(Bytecodes::Code code) { _orig_bytecode = code; }
  int         bci()                                   { return _bci; }

  BreakpointInfo*          next() const               { return _next; }
  void                 set_next(BreakpointInfo* n)    { _next = n; }

  // helps for searchers
  bool match(const Method* m, int bci) {
    return bci == _bci && match(m);
  }

  bool match(const Method* m) {
    return _name_index == m->name_index() &&
      _signature_index == m->signature_index();
  }

  void set(Method* method);
  void clear(Method* method);
};

#endif // INCLUDE_JVMTI

// Utility class for access exception handlers
class ExceptionTable : public StackObj {
 private:
  ExceptionTableElement* _table;
  u2  _length;

 public:
  ExceptionTable(const Method* m) {
    if (m->has_exception_handler()) {
      _table = m->exception_table_start();
      _length = m->exception_table_length();
    } else {
      _table = NULL;
      _length = 0;
    }
  }

  int length() const {
    return _length;
  }

  u2 start_pc(int idx) const {
    assert(idx < _length, "out of bounds");
    return _table[idx].start_pc;
  }

  void set_start_pc(int idx, u2 value) {
    assert(idx < _length, "out of bounds");
    _table[idx].start_pc = value;
  }

  u2 end_pc(int idx) const {
    assert(idx < _length, "out of bounds");
    return _table[idx].end_pc;
  }

  void set_end_pc(int idx, u2 value) {
    assert(idx < _length, "out of bounds");
    _table[idx].end_pc = value;
  }

  u2 handler_pc(int idx) const {
    assert(idx < _length, "out of bounds");
    return _table[idx].handler_pc;
  }

  void set_handler_pc(int idx, u2 value) {
    assert(idx < _length, "out of bounds");
    _table[idx].handler_pc = value;
  }

  u2 catch_type_index(int idx) const {
    assert(idx < _length, "out of bounds");
    return _table[idx].catch_type_index;
  }

  void set_catch_type_index(int idx, u2 value) {
    assert(idx < _length, "out of bounds");
    _table[idx].catch_type_index = value;
  }
};

#endif // SHARE_VM_OOPS_METHODOOP_HPP