methodOop.hpp

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/* Copyright 1994 - 1996 LongView Technologies L.L.C. $Revision: 1.89 $ */
/* Copyright (c) 2006, Sun Microsystems, Inc.
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// A methodOop is a method with byte codes.

const int method_size_mask_bitno  =  2;
const int method_size_mask_size   = 18;

const int method_args_mask_bitno  =  method_size_mask_bitno + method_size_mask_size;
const int method_args_mask_size   =  4;

const int method_flags_mask_bitno =  method_args_mask_bitno + method_args_mask_size;
const int method_flags_mask_size  =  8;


class methodOopDesc : public memOopDesc {
 private:
  objArrayOop _debugInfo;
  oop         _selector_or_method;      // selector for normal methods, enclosing method for blocks
  int         _counters;                // invocation counter and sharing counter
  smiOop      _size_and_flags;
  // [flags (8 bits),  nofArgs (4 bits), size in oops (18 bits), tag (2 bits)]
  methodOopDesc* addr() const           { return (methodOopDesc*)memOopDesc::addr(); }

  // returns the header size of a methodOop
  static int header_size()              { return sizeof(methodOopDesc)/oopSize; }

 public:
  // offsets for code generation
  static int selector_or_method_byte_offset()   { return int(&(((methodOopDesc*)NULL)->_selector_or_method)) - Mem_Tag; }
  static int counters_byte_offset()             { return int(&(((methodOopDesc*)NULL)->_counters)) - Mem_Tag; }
  static int codes_byte_offset()                { return sizeof(methodOopDesc) - Mem_Tag; }

  smiOop size_and_flags() const { return addr()->_size_and_flags; }     
  void set_size_and_flags(int size, int nofArgs, int flags) {
    addr()->_size_and_flags = (smiOop)
      ((flags << method_flags_mask_bitno) + (nofArgs << method_args_mask_bitno) + (size << method_size_mask_bitno));
  }

  int flags() const { 
    return get_unsigned_bitfield((int)size_and_flags(), method_flags_mask_bitno, method_flags_mask_size);
  }

  void set_flags(int flags) {
    set_size_and_flags(size_of_codes(), nofArgs(), flags);
  }

  int nofArgs() const {                  // number of arguments (excluding receiver)
    return get_unsigned_bitfield((int)size_and_flags(), method_args_mask_bitno, method_args_mask_size); }

 public:
  friend methodOop as_methodOop(void* p) { return methodOop(as_memOop(p)); }

  void bootstrap_object(bootstrap* st);

  // Tester
  bool is_blockMethod() const           { return !selector_or_method()->is_symbol(); }

  objArrayOop debugInfo() const         { return addr()->_debugInfo; }
  void set_debugInfo(objArrayOop d)     { addr()->_debugInfo = d; }

  symbolOop selector() const;
  methodOop parent() const;             // returns the enclosing block or method (for blocks), or NULL
  methodOop home() const;               // returns the enclosing method (for blocks), or itself

  oop  selector_or_method() const       { return addr()->_selector_or_method; }
  void set_selector_or_method(oop value){ addr()->_selector_or_method = value; }

  // returns the enclosing method's selector (block methods only)
  symbolOop enclosing_method_selector() const;

  // returns the source if the debugInfo is present, otherwise NULL.
  byteArrayOop source();

  // returns the tempInfo if the debugInfo is present, otherwise NULL.
  objArrayOop tempInfo();

  // Generates an array with fileout information.
  // The array contains pair of information:
  // (true,  SmallInteger) means character
  // (false, oop)          means oop
  objArrayOop fileout_body();

  // Accessor operaions on counters.
  //   invocation counter - tells how many times this methodOop has been executed (may decay over time)
  //   sharing counter    - tells how many callers this methodOop has.

  enum {
    _short_size              = 16,
    _invocation_count_offset = _short_size,
    _invocation_count_width  = _short_size,
    _invocation_count_max    = (1 << _short_size) - 1,

    _sharing_count_offset    = 0,
    _sharing_count_width     = _short_size,
    _sharing_count_max       = (1 << _short_size) - 1
  };

  int  counters() const                 { return addr()->_counters; }
  void set_counters(int inv, int share) { addr()->_counters = (inv << _invocation_count_offset) | share; }

  // Invocation counter
  int invocation_count() const          { return get_unsigned_bitfield(counters(), _invocation_count_offset, _invocation_count_width); }
  void set_invocation_count(int value)  { set_counters(value, sharing_count()); }

  void decay_invocation_count(double decay_factor);
  
  // Sharing counter (number of callers)
  int sharing_count() const             { return get_unsigned_bitfield(counters(), _sharing_count_offset, _sharing_count_width); }
  void set_sharing_count(int value)     { set_counters(invocation_count(), value); }
  void inc_sharing_count();
  void dec_sharing_count();

  bool was_never_executed();            // was method never executed? (count = 0, empty inline caches)

  int size_of_codes() const {           // size of byte codes in words
    return get_unsigned_bitfield((int) size_and_flags(), method_size_mask_bitno, method_size_mask_size); 
  }

  void set_size_of_code(int size) {
    set_size_and_flags(size, nofArgs(), flags());
  }

  // Returns a pointer to the hybrid code at 'offset'
  u_char* codes(int offset = 1) const {
     return (u_char*) addr() + sizeof(methodOopDesc) + offset - 1;
  }

  u_char* codes_end() const {
     return codes() + size_of_codes() * oopSize;
  }

  // find methodOop given an hcode pointer 
  static methodOop methodOop_from_hcode(u_char* hp);

  u_char byte_at(int offset) const              { return *codes(offset); }
  void byte_at_put(int offset,u_char c)         { *codes(offset) = c; }

  long word_at(int offset) const                { return * (long*) codes(offset); }
  void word_at_put(int offset,unsigned long w)  { * (long*) codes(offset) = w; }

  oop  oop_at(int offset) const                 { return * (oop*) codes(offset); }
  void oop_at_put(int offset,oop obj)           { * (oop*) codes(offset) = obj; }

  // Returns the next byte code index based on hp.
  int  next_bci_from(u_char* hp) const;

  // Returns the current byte code index based on hp (points to the next byte code)
  int  bci_from(u_char* hp) const;

  int  number_of_arguments() const;

  // Returns the number of temporaries allocated by the interpreter
  // (excluding receiver & float temporaries, which may come afterwards).
  int number_of_stack_temporaries() const;

  // Method with hardwired floating-point operations
  bool has_float_temporaries() const            { return *codes(1) == Bytecodes::float_allocate; }
  int  number_of_float_temporaries() const      { return has_float_temporaries() ? *codes(3) : 0; }
  int  float_expression_stack_size() const      { return has_float_temporaries() ? *codes(4) : 0; }
  int  total_number_of_floats() const           { return number_of_float_temporaries() + float_expression_stack_size(); }

  // Stack frame layout if there's a float section (offset & size in oops relative to ebp)
  int  float_offset(int float_no) const;
  int  float_section_start_offset() const       { return frame_temp_offset - number_of_stack_temporaries(); }
  int  float_section_size() const               { return total_number_of_floats()*floatSize/oopSize; }

  // Testers
  bool is_accessMethod() const                  { return *codes() == Bytecodes::return_instVar; }
  bool is_primitiveMethod() const;

  // For predicted sends (smi +, -, *, etc.)
  bool is_special_primitiveMethod() const       { return *codes(1) == Bytecodes::special_primitive_send_1_hint; }
  Bytecodes::Code special_primitive_code() const;


  // Information needed by the optimizing compiler
  //
  // Incoming_Info describes the possible oop kinds that a methodOop gets 'from' the
  // outside (via the closure) when invoked. Currently, the incoming oop is stored in
  // the recv and temp0 stack location for blocks, and in the recv location only for
  // methods (ordinary send). This should change at some point and the incoming oop
  // should be stored in the recv location only (allows better stack usage).
  //
  // Temporaries_Info is used to compute the number of stack-allocated temporaries. If
  // more than two temporaries are needed, the very first bytecode is an allocate temp
  // byte code (bytecode invariant).

  enum Flags {
    // general flags
    containsNLRFlag     = 0,
    allocatesContextFlag= 1,
    mustBeCustomizedFlag= 2,
    isCustomizedFlag    = 3,

    // method specific flags (overlapping with block specific flags)
    methodInfoFlags     = isCustomizedFlag + 1,
    methodInfoSize      = 2,

    // block specific flags (overlapping with method specific flags)
    blockInfoFlags      = methodInfoFlags,
    blockInfoSize       = methodInfoSize
  };

  // Flags for inlining
  enum Method_Inlining_Info {
    never_inline  = 0,
    normal_inline = 1,
    always_inline = 2,
  } method_inlining_info() const;

  void set_method_inlining_info(Method_Inlining_Info info);

  enum Block_Info {
    expects_nil         = 0,                    // 'clean' block
    expects_self        = 1,                    // 'copying' block
    expects_parameter   = 2,                    // 'copying' block
    expects_context     = 3                     // 'full' block
  } block_info() const;

  // Tells if an activation of this method has a context stored as temp 0.
  bool activation_has_context() const { 
    return allocatesInterpretedContext()
        || (is_blockMethod() && expectsContext());
  }

  // Tells if bci is a context allocation
  bool in_context_allocation(int bci) const;

  bool containsNLR() const                      { return isSet(flags(), containsNLRFlag); }
  bool allocatesInterpretedContext() const      { return isSet(flags(), allocatesContextFlag); }
  bool mustBeCustomizedToClass() const          { return isSet(flags(), mustBeCustomizedFlag); }
  bool expectsContext() const                   { return block_info() == expects_context; }
  bool hasNestedBlocks() const;
  bool is_clean_block() const                   { return block_info() == expects_nil; }
  bool is_copying_block() const                 { return block_info() == expects_self || block_info() == expects_parameter; }
  bool is_full_block() const                    { return block_info() == expects_context; }

  // Method customization
  bool has_instVar_access() const               { return true; } // for now - conservative - FIX THIS
  bool has_classVar_access() const              { return true; } // for now - conservative - FIX THIS
  bool has_inlineCache() const                  { return true; } // for now - conservative - FIX THIS
  bool is_customized() const                    { return isSet(flags(), isCustomizedFlag); }                    
  bool should_be_customized() const             { return has_instVar_access() || has_classVar_access() || has_inlineCache(); }

  // Returns a deep copy of the methodOop
  methodOop copy_for_customization() const;

  // Customize method to klass
  void customize_for(klassOop klass, mixinOop mixin);
  void uncustomize_for(mixinOop mixin);

  // Uplevel accesses via contexts
  int lexicalDistance(int contextNo);   // for uplevel accesses; see comment in .c file
  int contextNo(int lexicalDistance);   // inverse of lexicalDistance()

  // Computes the number of interpreter contexts from here up to the home method
  int context_chain_length() const;

  // Clears all the inline caches in the method.
  void clear_inline_caches();

  // Cleanup all inline caches
  void cleanup_inline_caches();

  // Computes the estimated cost of a method by summing 
  // cost of all byte codes (see code_cost in methodOop.cpp).
  int estimated_inline_cost(klassOop receiverKlass);

  // Finds the bci based on the next bci
  // Returns -1 if the search failed.
  int find_bci_from(int nbci) const;

  // Returns the next bci
  int next_bci(int bci) const;

  // Returns the end bci (excluding the padding)
  int end_bci() const;

  // Returns the inline cache associated with the send at bci.
  InterpretedIC* ic_at(int bci) const;

  // Returns an array of byte code indecies contributing to the expression stack
  GrowableArray<int>* expression_stack_mapping(int bci);

  // For debugging only
  void print_codes();
  void pretty_print();

  // Printing support
  void print_value_for(klassOop receiver_klass, outputStream* st = NULL);

  // Inlining database support
  void print_inlining_database_on(outputStream* st);
  int  bci_for_block_method(methodOop inner);
  methodOop block_method_at(int bci);

  // Returns the numbers of temporaries allocated in a context.
  // self_in_context tells if self is copied into context.
  // Note: This function is extremely slow, so please use it for
  //       verify and debug code only.
  int number_of_context_temporaries(bool* self_in_context = NULL);

  // Checks if the context matches this method
  void verify_context(contextOop con);

  // Query primitives
  objArrayOop referenced_instance_variable_names(mixinOop mixin) const;
  objArrayOop referenced_class_variable_names() const;
  objArrayOop referenced_global_names() const;
  objArrayOop senders() const;

  friend methodKlass;
};

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