svn merge -r 217500:218679 svn+ssh://gcc.gnu.org/svn/gcc/trunk
[official-gcc.git] / gcc / inchash.h
blobc157e302509feeff120fe538d5c273a53e19ce08
1 /* An incremental hash abstract data type.
2 Copyright (C) 2014 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
9 version.
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
14 for more details.
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/>. */
20 #ifndef INCHASH_H
21 #define INCHASH_H 1
23 #include "config.h"
24 #include "system.h"
25 #include "coretypes.h"
26 #include "hashtab.h"
28 /* This file implements an incremential hash function ADT, to be used
29 by code that incrementially hashes a lot of unrelated data
30 (not in a single memory block) into a single value. The goal
31 is to make it easy to plug in efficient hash algorithms.
32 Currently it just implements the plain old jhash based
33 incremental hash from gcc's tree.c. */
35 extern hashval_t iterative_hash_host_wide_int (HOST_WIDE_INT, hashval_t);
36 extern hashval_t iterative_hash_hashval_t (hashval_t, hashval_t);
38 namespace inchash
41 class hash
43 public:
45 /* Start incremential hashing, optionally with SEED. */
46 hash (hashval_t seed = 0)
48 val = seed;
49 bits = 0;
52 /* End incremential hashing and provide the final value. */
53 hashval_t end ()
55 return val;
58 /* Add unsigned value V. */
59 void add_int (unsigned v)
61 val = iterative_hash_hashval_t (v, val);
64 /* Add HOST_WIDE_INT value V. */
65 void add_wide_int (HOST_WIDE_INT v)
67 val = iterative_hash_host_wide_int (v, val);
70 /* Hash in pointer PTR. */
71 void add_ptr (void *ptr)
73 add (&ptr, sizeof (ptr));
76 /* Add a memory block DATA with size LEN. */
77 void add (const void *data, size_t len)
79 val = iterative_hash (data, len, val);
82 /* Merge hash value OTHER. */
83 void merge_hash (hashval_t other)
85 val = iterative_hash_hashval_t (other, val);
88 /* Hash in state from other inchash OTHER. */
89 void merge (hash &other)
91 merge_hash (other.val);
94 template<class T> void add_object(T &obj)
96 add (&obj, sizeof(T));
99 /* Support for accumulating boolean flags */
101 void add_flag (bool flag)
103 bits = (bits << 1) | flag;
106 void commit_flag ()
108 add_int (bits);
109 bits = 0;
112 /* Support for commutative hashing. Add A and B in a defined order
113 based on their value. This is useful for hashing commutative
114 expressions, so that A+B and B+A get the same hash. */
116 void add_commutative (hash &a, hash &b)
118 if (a.end() > b.end())
120 merge (b);
121 merge (a);
123 else
125 merge (a);
126 merge (b);
130 private:
131 hashval_t val;
132 unsigned bits;
137 #endif