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6b214d09 | 1 | /* An incremental hash abstract data type. |
fbd26352 | 2 | Copyright (C) 2014-2019 Free Software Foundation, Inc. |
6b214d09 | 3 | |
4 | This file is part of GCC. | |
5 | ||
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. | |
10 | ||
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. | |
15 | ||
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/>. */ | |
19 | ||
20 | #ifndef INCHASH_H | |
21 | #define INCHASH_H 1 | |
22 | ||
6b214d09 | 23 | |
24 | /* This file implements an incremential hash function ADT, to be used | |
25 | by code that incrementially hashes a lot of unrelated data | |
26 | (not in a single memory block) into a single value. The goal | |
27 | is to make it easy to plug in efficient hash algorithms. | |
28 | Currently it just implements the plain old jhash based | |
29 | incremental hash from gcc's tree.c. */ | |
30 | ||
0ff42de5 | 31 | hashval_t iterative_hash_host_wide_int (HOST_WIDE_INT, hashval_t); |
32 | hashval_t iterative_hash_hashval_t (hashval_t, hashval_t); | |
6b214d09 | 33 | |
7fdbd1ec | 34 | namespace inchash |
35 | { | |
36 | ||
37 | class hash | |
6b214d09 | 38 | { |
39 | public: | |
40 | ||
41 | /* Start incremential hashing, optionally with SEED. */ | |
7fdbd1ec | 42 | hash (hashval_t seed = 0) |
6b214d09 | 43 | { |
44 | val = seed; | |
45 | bits = 0; | |
46 | } | |
47 | ||
48 | /* End incremential hashing and provide the final value. */ | |
49 | hashval_t end () | |
50 | { | |
51 | return val; | |
52 | } | |
53 | ||
54 | /* Add unsigned value V. */ | |
55 | void add_int (unsigned v) | |
56 | { | |
57 | val = iterative_hash_hashval_t (v, val); | |
58 | } | |
59 | ||
fe60c82c | 60 | /* Add polynomial value V, treating each element as an unsigned int. */ |
61 | template<unsigned int N, typename T> | |
62 | void add_poly_int (const poly_int_pod<N, T> &v) | |
63 | { | |
64 | for (unsigned int i = 0; i < N; ++i) | |
65 | add_int (v.coeffs[i]); | |
66 | } | |
67 | ||
6b214d09 | 68 | /* Add HOST_WIDE_INT value V. */ |
eadcd69c | 69 | void add_hwi (HOST_WIDE_INT v) |
6b214d09 | 70 | { |
71 | val = iterative_hash_host_wide_int (v, val); | |
72 | } | |
73 | ||
a14d43f8 | 74 | /* Add polynomial value V, treating each element as a HOST_WIDE_INT. */ |
75 | template<unsigned int N, typename T> | |
76 | void add_poly_hwi (const poly_int_pod<N, T> &v) | |
77 | { | |
78 | for (unsigned int i = 0; i < N; ++i) | |
79 | add_hwi (v.coeffs[i]); | |
80 | } | |
81 | ||
ca6b9aed | 82 | /* Add wide_int-based value V. */ |
83 | template<typename T> | |
84 | void add_wide_int (const generic_wide_int<T> &x) | |
85 | { | |
86 | add_int (x.get_len ()); | |
87 | for (unsigned i = 0; i < x.get_len (); i++) | |
88 | add_hwi (x.elt (i)); | |
89 | } | |
90 | ||
6b214d09 | 91 | /* Hash in pointer PTR. */ |
0ff42de5 | 92 | void add_ptr (const void *ptr) |
6b214d09 | 93 | { |
94 | add (&ptr, sizeof (ptr)); | |
95 | } | |
96 | ||
97 | /* Add a memory block DATA with size LEN. */ | |
98 | void add (const void *data, size_t len) | |
99 | { | |
100 | val = iterative_hash (data, len, val); | |
101 | } | |
102 | ||
103 | /* Merge hash value OTHER. */ | |
104 | void merge_hash (hashval_t other) | |
105 | { | |
106 | val = iterative_hash_hashval_t (other, val); | |
107 | } | |
108 | ||
109 | /* Hash in state from other inchash OTHER. */ | |
7fdbd1ec | 110 | void merge (hash &other) |
6b214d09 | 111 | { |
112 | merge_hash (other.val); | |
113 | } | |
114 | ||
7fdbd1ec | 115 | template<class T> void add_object(T &obj) |
116 | { | |
117 | add (&obj, sizeof(T)); | |
118 | } | |
119 | ||
6b214d09 | 120 | /* Support for accumulating boolean flags */ |
121 | ||
122 | void add_flag (bool flag) | |
123 | { | |
124 | bits = (bits << 1) | flag; | |
125 | } | |
126 | ||
127 | void commit_flag () | |
128 | { | |
129 | add_int (bits); | |
130 | bits = 0; | |
131 | } | |
132 | ||
133 | /* Support for commutative hashing. Add A and B in a defined order | |
134 | based on their value. This is useful for hashing commutative | |
135 | expressions, so that A+B and B+A get the same hash. */ | |
136 | ||
7fdbd1ec | 137 | void add_commutative (hash &a, hash &b) |
6b214d09 | 138 | { |
139 | if (a.end() > b.end()) | |
140 | { | |
0ff42de5 | 141 | merge (b); |
6b214d09 | 142 | merge (a); |
143 | } | |
144 | else | |
145 | { | |
0ff42de5 | 146 | merge (a); |
147 | merge (b); | |
6b214d09 | 148 | } |
149 | } | |
150 | ||
151 | private: | |
152 | hashval_t val; | |
153 | unsigned bits; | |
154 | }; | |
155 | ||
7fdbd1ec | 156 | } |
6b214d09 | 157 | |
0ff42de5 | 158 | /* Borrowed from hashtab.c iterative_hash implementation. */ |
159 | #define mix(a,b,c) \ | |
160 | { \ | |
161 | a -= b; a -= c; a ^= (c>>13); \ | |
162 | b -= c; b -= a; b ^= (a<< 8); \ | |
163 | c -= a; c -= b; c ^= ((b&0xffffffff)>>13); \ | |
164 | a -= b; a -= c; a ^= ((c&0xffffffff)>>12); \ | |
165 | b -= c; b -= a; b = (b ^ (a<<16)) & 0xffffffff; \ | |
166 | c -= a; c -= b; c = (c ^ (b>> 5)) & 0xffffffff; \ | |
167 | a -= b; a -= c; a = (a ^ (c>> 3)) & 0xffffffff; \ | |
168 | b -= c; b -= a; b = (b ^ (a<<10)) & 0xffffffff; \ | |
169 | c -= a; c -= b; c = (c ^ (b>>15)) & 0xffffffff; \ | |
170 | } | |
171 | ||
172 | ||
173 | /* Produce good hash value combining VAL and VAL2. */ | |
174 | inline | |
175 | hashval_t | |
176 | iterative_hash_hashval_t (hashval_t val, hashval_t val2) | |
177 | { | |
178 | /* the golden ratio; an arbitrary value. */ | |
179 | hashval_t a = 0x9e3779b9; | |
180 | ||
181 | mix (a, val, val2); | |
182 | return val2; | |
183 | } | |
184 | ||
185 | /* Produce good hash value combining VAL and VAL2. */ | |
186 | ||
187 | inline | |
188 | hashval_t | |
189 | iterative_hash_host_wide_int (HOST_WIDE_INT val, hashval_t val2) | |
190 | { | |
191 | if (sizeof (HOST_WIDE_INT) == sizeof (hashval_t)) | |
192 | return iterative_hash_hashval_t (val, val2); | |
193 | else | |
194 | { | |
195 | hashval_t a = (hashval_t) val; | |
196 | /* Avoid warnings about shifting of more than the width of the type on | |
197 | hosts that won't execute this path. */ | |
198 | int zero = 0; | |
199 | hashval_t b = (hashval_t) (val >> (sizeof (hashval_t) * 8 + zero)); | |
200 | mix (a, b, val2); | |
201 | if (sizeof (HOST_WIDE_INT) > 2 * sizeof (hashval_t)) | |
202 | { | |
203 | hashval_t a = (hashval_t) (val >> (sizeof (hashval_t) * 16 + zero)); | |
204 | hashval_t b = (hashval_t) (val >> (sizeof (hashval_t) * 24 + zero)); | |
205 | mix (a, b, val2); | |
206 | } | |
207 | return val2; | |
208 | } | |
209 | } | |
210 | ||
6b214d09 | 211 | #endif |