lookupCache.hpp

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/* Copyright 1994 - 1996 LongView Technologies L.L.C. $Revision: 1.38 $ */
/* Copyright (c) 2006, Sun Microsystems, Inc.
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// The lookup cache is a 2-way associative cache mapping LookupKeys into LookupResult.
// Called when the inline cache fails or when a compile takes place.

// %gc-note
// When a garbage collect occurs the lookup cache has to be 
// recomputed since the has value is dependent on the location
// of symbols and klasses.

class LookupResult: ValueObj {
 protected:
  oop _result; // methodOop or jumpTableEntry

 public:
  // Constructors
  LookupResult()                 { clear();     }
  LookupResult(methodOop method) { set(method); }
  LookupResult(nmethod*  nm)     { set(nm);     }

  // Clears the result
  void clear() { _result = NULL; }

  // Test operations
  bool is_empty()  const { return _result == NULL;   }
  bool is_method() const { return _result->is_mem(); }
  bool is_entry()  const { return !is_method();      }


  // Maching operations
  bool matches(methodOop m) const; // Checks whether the result is methodOop m.
  bool matches(nmethod* nm) const; // Checks whether the result is nmethod nm.

  // Fetch operations
  oop             value()       const { return _result; }
  methodOop       method()      const;
  methodOop       method_or_null() const;
  jumpTableEntry* entry()       const;
  nmethod*        get_nmethod() const;
  
  // Set operations
  void set(methodOop method) {
    assert(method->is_method(), "must be method");
    _result = oop(method);
  }

  void set(nmethod* nm) {
    assert(oop(nm)->is_smi(), "nmethod must be aligned");
    _result = oop(nm->jump_table_entry()->entry_point());
  }

  void print_on(outputStream* st) const;
  void print_short_on(outputStream* st) const;
};


const unsigned int primary_cache_size   = 16 * K;
const unsigned int secondary_cache_size =  2 * K;

class lookupCache : AllStatic {
 private:
  static int primary_cache_address();
  static int secondary_cache_address();

  static unsigned int hash_value(LookupKey* key);
  static int number_of_primary_hits;
  static int number_of_secondary_hits;
  static int number_of_misses;

  static inline LookupResult ic_lookup(klassOop receiver_klass, oop selector_or_method);

  static LookupResult lookup(LookupKey* key, bool compile);
  static LookupResult cache_miss_lookup(LookupKey* key, bool compile);
  static nmethod* compile_method(LookupKey* key, methodOop method);

 public:
  // Lookup probe into the lookup cache
  static LookupResult lookup_probe(LookupKey* key);

  // Lookup support for inline cache (returns methodOop or jump_table_entry).
  static LookupResult ic_normal_lookup(klassOop receiver_klass, symbolOop selector);
  static LookupResult ic_super_lookup(klassOop receiver_klass, klassOop sending_method_holder, symbolOop selector);

  // Lookup support for interpreter  (returns methodOop or jump_table_entry).
  friend LookupResult interpreter_normal_lookup(klassOop receiver_klass, symbolOop selector);
  friend LookupResult interpreter_super_lookup(symbolOop selector);

  // Lookup support for compiler
  static methodOop method_lookup(klassOop receiver_klass, symbolOop selector);
  static methodOop compile_time_normal_lookup(klassOop receiver_klass, symbolOop selector);     // returns NULL if not found
  static methodOop compile_time_super_lookup (klassOop receiver_klass, symbolOop selector);     // returns NULL if not found

  // Lookup support for LookupKey
  static LookupResult lookup(LookupKey* key);

  // Lookup support for megamorphic sends (no super sends)
  static oop normal_lookup(klassOop receiver_klass, symbolOop selector);                        // returns {methodOop or jump table entry}

  // Flushing
  static void flush(LookupKey* key);
  static void flush();

  // Clear all entries in the cache.
  static void verify();

  static void clear_statistics();
  static void print_statistics();

  friend class InterpreterGenerator;
  friend class StubRoutines;
  friend class debugPrimitives;
};

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