]>
Commit | Line | Data |
---|---|---|
6d8eb96b | 1 | /* Incremential hashing for jhash. |
5624e564 | 2 | Copyright (C) 2014-2015 Free Software Foundation, Inc. |
6d8eb96b AK |
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 | #include "config.h" | |
21 | #include "system.h" | |
22 | #include "coretypes.h" | |
23 | #include "hashtab.h" | |
24 | #include "inchash.h" | |
25 | ||
26 | /* Borrowed from hashtab.c iterative_hash implementation. */ | |
27 | #define mix(a,b,c) \ | |
28 | { \ | |
29 | a -= b; a -= c; a ^= (c>>13); \ | |
30 | b -= c; b -= a; b ^= (a<< 8); \ | |
31 | c -= a; c -= b; c ^= ((b&0xffffffff)>>13); \ | |
32 | a -= b; a -= c; a ^= ((c&0xffffffff)>>12); \ | |
33 | b -= c; b -= a; b = (b ^ (a<<16)) & 0xffffffff; \ | |
34 | c -= a; c -= b; c = (c ^ (b>> 5)) & 0xffffffff; \ | |
35 | a -= b; a -= c; a = (a ^ (c>> 3)) & 0xffffffff; \ | |
36 | b -= c; b -= a; b = (b ^ (a<<10)) & 0xffffffff; \ | |
37 | c -= a; c -= b; c = (c ^ (b>>15)) & 0xffffffff; \ | |
38 | } | |
39 | ||
40 | ||
41 | /* Produce good hash value combining VAL and VAL2. */ | |
42 | hashval_t | |
43 | iterative_hash_hashval_t (hashval_t val, hashval_t val2) | |
44 | { | |
45 | /* the golden ratio; an arbitrary value. */ | |
46 | hashval_t a = 0x9e3779b9; | |
47 | ||
48 | mix (a, val, val2); | |
49 | return val2; | |
50 | } | |
51 | ||
52 | /* Produce good hash value combining VAL and VAL2. */ | |
53 | ||
54 | hashval_t | |
55 | iterative_hash_host_wide_int (HOST_WIDE_INT val, hashval_t val2) | |
56 | { | |
57 | if (sizeof (HOST_WIDE_INT) == sizeof (hashval_t)) | |
58 | return iterative_hash_hashval_t (val, val2); | |
59 | else | |
60 | { | |
61 | hashval_t a = (hashval_t) val; | |
62 | /* Avoid warnings about shifting of more than the width of the type on | |
63 | hosts that won't execute this path. */ | |
64 | int zero = 0; | |
65 | hashval_t b = (hashval_t) (val >> (sizeof (hashval_t) * 8 + zero)); | |
66 | mix (a, b, val2); | |
67 | if (sizeof (HOST_WIDE_INT) > 2 * sizeof (hashval_t)) | |
68 | { | |
69 | hashval_t a = (hashval_t) (val >> (sizeof (hashval_t) * 16 + zero)); | |
70 | hashval_t b = (hashval_t) (val >> (sizeof (hashval_t) * 24 + zero)); | |
71 | mix (a, b, val2); | |
72 | } | |
73 | return val2; | |
74 | } | |
75 | } |