gcc/

[thirdparty/gcc.git] / gcc / hash-traits.h

/* Traits for hashable types.
   Copyright (C) 2014-2015 Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.

GCC 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
for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */

#ifndef hash_traits_h
#define hash_traits_h

/* Helpful type for removing with free.  */

template <typename Type>
struct typed_free_remove
{
  static inline void remove (Type *p);
};


/* Remove with free.  */

template <typename Type>
inline void
typed_free_remove <Type>::remove (Type *p)
{
  free (p);
}


/* Helpful type for a no-op remove.  */

template <typename Type>
struct typed_noop_remove
{
  static inline void remove (Type *p);
};


/* Remove doing nothing.  */

template <typename Type>
inline void
typed_noop_remove <Type>::remove (Type *p ATTRIBUTE_UNUSED)
{
}


/* Pointer hash with a no-op remove method.  */

template <typename Type>
struct pointer_hash : typed_noop_remove <Type>
{
  typedef Type *value_type;
  typedef Type *compare_type;

  static inline hashval_t hash (const value_type &);
  static inline bool equal (const value_type &existing,
			    const compare_type &candidate);
  static inline void mark_deleted (Type *&);
  static inline void mark_empty (Type *&);
  static inline bool is_deleted (Type *);
  static inline bool is_empty (Type *);
};

template <typename Type>
inline hashval_t
pointer_hash <Type>::hash (const value_type &candidate)
{
  /* This is a really poor hash function, but it is what the current code uses,
     so I am reusing it to avoid an additional axis in testing.  */
  return (hashval_t) ((intptr_t)candidate >> 3);
}

template <typename Type>
inline bool
pointer_hash <Type>::equal (const value_type &existing,
			   const compare_type &candidate)
{
  return existing == candidate;
}

template <typename Type>
inline void
pointer_hash <Type>::mark_deleted (Type *&e)
{
  e = reinterpret_cast<Type *> (1);
}

template <typename Type>
inline void
pointer_hash <Type>::mark_empty (Type *&e)
{
  e = NULL;
}

template <typename Type>
inline bool
pointer_hash <Type>::is_deleted (Type *e)
{
  return e == reinterpret_cast<Type *> (1);
}

template <typename Type>
inline bool
pointer_hash <Type>::is_empty (Type *e)
{
  return e == NULL;
}

/* Hasher for entry in gc memory.  */

template<typename T>
struct ggc_hasher
{
  typedef T value_type;
  typedef T compare_type;

  static void remove (T &) {}

  static void
  ggc_mx (T &p)
  {
    extern void gt_ggc_mx (T &);
    gt_ggc_mx (p);
  }

  static void
  pch_nx (T &p)
  {
    extern void gt_pch_nx (T &);
    gt_pch_nx (p);
  }

  static void
  pch_nx (T &p, gt_pointer_operator op, void *cookie)
  {
    op (&p, cookie);
  }
};

/* Hasher for cache entry in gc memory.  */

template<typename T>
struct ggc_cache_hasher : ggc_hasher<T>
{
  /* Entries are weakly held because this is for caches.  */
  static void ggc_mx (T &) {}

  static int
  keep_cache_entry (T &e)
  {
    return ggc_marked_p (e) ? -1 : 0;
  }
};

#endif