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git.ipfire.org Git - thirdparty/gcc.git/blob - gcc/hash-traits.h
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1 /* Traits for hashable types.
2 Copyright (C) 2014-2015 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
23 /* Helpful type for removing with free. */
25 template <typename Type
>
26 struct typed_free_remove
28 static inline void remove (Type
*p
);
32 /* Remove with free. */
34 template <typename Type
>
36 typed_free_remove
<Type
>::remove (Type
*p
)
42 /* Helpful type for a no-op remove. */
44 template <typename Type
>
45 struct typed_noop_remove
47 static inline void remove (Type
*p
);
51 /* Remove doing nothing. */
53 template <typename Type
>
55 typed_noop_remove
<Type
>::remove (Type
*p ATTRIBUTE_UNUSED
)
60 /* Pointer hasher based on pointer equality. Other types of pointer hash
61 can inherit this and override the hash and equal functions with some
62 other form of equality (such as string equality). */
64 template <typename Type
>
67 typedef Type
*value_type
;
68 typedef Type
*compare_type
;
70 static inline hashval_t
hash (const value_type
&);
71 static inline bool equal (const value_type
&existing
,
72 const compare_type
&candidate
);
73 static inline void mark_deleted (Type
*&);
74 static inline void mark_empty (Type
*&);
75 static inline bool is_deleted (Type
*);
76 static inline bool is_empty (Type
*);
79 template <typename Type
>
81 pointer_hash
<Type
>::hash (const value_type
&candidate
)
83 /* This is a really poor hash function, but it is what the current code uses,
84 so I am reusing it to avoid an additional axis in testing. */
85 return (hashval_t
) ((intptr_t)candidate
>> 3);
88 template <typename Type
>
90 pointer_hash
<Type
>::equal (const value_type
&existing
,
91 const compare_type
&candidate
)
93 return existing
== candidate
;
96 template <typename Type
>
98 pointer_hash
<Type
>::mark_deleted (Type
*&e
)
100 e
= reinterpret_cast<Type
*> (1);
103 template <typename Type
>
105 pointer_hash
<Type
>::mark_empty (Type
*&e
)
110 template <typename Type
>
112 pointer_hash
<Type
>::is_deleted (Type
*e
)
114 return e
== reinterpret_cast<Type
*> (1);
117 template <typename Type
>
119 pointer_hash
<Type
>::is_empty (Type
*e
)
124 /* Hasher for entry in gc memory. */
129 typedef T value_type
;
130 typedef T compare_type
;
132 static void remove (T
&) {}
137 extern void gt_ggc_mx (T
&);
144 extern void gt_pch_nx (T
&);
149 pch_nx (T
&p
, gt_pointer_operator op
, void *cookie
)
155 /* Hasher for cache entry in gc memory. */
158 struct ggc_cache_hasher
: ggc_hasher
<T
>
160 /* Entries are weakly held because this is for caches. */
161 static void ggc_mx (T
&) {}
164 keep_cache_entry (T
&e
)
166 return ggc_marked_p (e
) ? -1 : 0;
170 /* Traits for pointer elements that should not be freed when an element
173 template <typename T
>
174 struct nofree_ptr_hash
: pointer_hash
<T
>, typed_noop_remove
<T
> {};
176 /* Traits for pointer elements that should be freed via free() when an
177 element is deleted. */
179 template <typename T
>
180 struct free_ptr_hash
: pointer_hash
<T
>, typed_free_remove
<T
> {};