LLVM  6.0.0svn
xxhash.cpp
Go to the documentation of this file.
1 /*
2 * xxHash - Fast Hash algorithm
3 * Copyright (C) 2012-2016, Yann Collet
4 *
5 * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions are
9 * met:
10 *
11 * * Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * * Redistributions in binary form must reproduce the above
14 * copyright notice, this list of conditions and the following disclaimer
15 * in the documentation and/or other materials provided with the
16 * distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 *
30 * You can contact the author at :
31 * - xxHash homepage: http://www.xxhash.com
32 * - xxHash source repository : https://github.com/Cyan4973/xxHash
33 */
34 
35 /* based on revision d2df04efcbef7d7f6886d345861e5dfda4edacc1 Removed
36  * everything but a simple interface for computing XXh64. */
37 
38 #include "llvm/Support/xxhash.h"
39 #include "llvm/Support/Endian.h"
40 
41 #include <stdlib.h>
42 #include <string.h>
43 
44 using namespace llvm;
45 using namespace support;
46 
47 static uint64_t rotl64(uint64_t X, size_t R) {
48  return (X << R) | (X >> (64 - R));
49 }
50 
51 static const uint64_t PRIME64_1 = 11400714785074694791ULL;
52 static const uint64_t PRIME64_2 = 14029467366897019727ULL;
53 static const uint64_t PRIME64_3 = 1609587929392839161ULL;
54 static const uint64_t PRIME64_4 = 9650029242287828579ULL;
55 static const uint64_t PRIME64_5 = 2870177450012600261ULL;
56 
57 static uint64_t round(uint64_t Acc, uint64_t Input) {
58  Acc += Input * PRIME64_2;
59  Acc = rotl64(Acc, 31);
60  Acc *= PRIME64_1;
61  return Acc;
62 }
63 
64 static uint64_t mergeRound(uint64_t Acc, uint64_t Val) {
65  Val = round(0, Val);
66  Acc ^= Val;
67  Acc = Acc * PRIME64_1 + PRIME64_4;
68  return Acc;
69 }
70 
71 uint64_t llvm::xxHash64(StringRef Data) {
72  size_t Len = Data.size();
73  uint64_t Seed = 0;
74  const char *P = Data.data();
75  const char *const BEnd = P + Len;
76  uint64_t H64;
77 
78  if (Len >= 32) {
79  const char *const Limit = BEnd - 32;
80  uint64_t V1 = Seed + PRIME64_1 + PRIME64_2;
81  uint64_t V2 = Seed + PRIME64_2;
82  uint64_t V3 = Seed + 0;
83  uint64_t V4 = Seed - PRIME64_1;
84 
85  do {
86  V1 = round(V1, endian::read64le(P));
87  P += 8;
88  V2 = round(V2, endian::read64le(P));
89  P += 8;
90  V3 = round(V3, endian::read64le(P));
91  P += 8;
92  V4 = round(V4, endian::read64le(P));
93  P += 8;
94  } while (P <= Limit);
95 
96  H64 = rotl64(V1, 1) + rotl64(V2, 7) + rotl64(V3, 12) + rotl64(V4, 18);
97  H64 = mergeRound(H64, V1);
98  H64 = mergeRound(H64, V2);
99  H64 = mergeRound(H64, V3);
100  H64 = mergeRound(H64, V4);
101 
102  } else {
103  H64 = Seed + PRIME64_5;
104  }
105 
106  H64 += (uint64_t)Len;
107 
108  while (P + 8 <= BEnd) {
109  uint64_t const K1 = round(0, endian::read64le(P));
110  H64 ^= K1;
111  H64 = rotl64(H64, 27) * PRIME64_1 + PRIME64_4;
112  P += 8;
113  }
114 
115  if (P + 4 <= BEnd) {
116  H64 ^= (uint64_t)(endian::read32le(P)) * PRIME64_1;
117  H64 = rotl64(H64, 23) * PRIME64_2 + PRIME64_3;
118  P += 4;
119  }
120 
121  while (P < BEnd) {
122  H64 ^= (*P) * PRIME64_5;
123  H64 = rotl64(H64, 11) * PRIME64_1;
124  P++;
125  }
126 
127  H64 ^= H64 >> 33;
128  H64 *= PRIME64_2;
129  H64 ^= H64 >> 29;
130  H64 *= PRIME64_3;
131  H64 ^= H64 >> 32;
132 
133  return H64;
134 }
static const uint64_t PRIME64_4
Definition: xxhash.cpp:54
static GCMetadataPrinterRegistry::Add< ErlangGCPrinter > X("erlang", "erlang-compatible garbage collector")
static const uint64_t PRIME64_2
Definition: xxhash.cpp:52
static cl::opt< unsigned long long > Seed("rng-seed", cl::value_desc("seed"), cl::desc("Seed for the random number generator"), cl::init(0))
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
static uint64_t rotl64(uint64_t X, size_t R)
Definition: xxhash.cpp:47
LLVM_NODISCARD LLVM_ATTRIBUTE_ALWAYS_INLINE size_t size() const
size - Get the string size.
Definition: StringRef.h:138
uint64_t xxHash64(llvm::StringRef Data)
Definition: xxhash.cpp:71
static uint64_t round(uint64_t Acc, uint64_t Input)
Definition: xxhash.cpp:57
LLVM_NODISCARD LLVM_ATTRIBUTE_ALWAYS_INLINE const char * data() const
data - Get a pointer to the start of the string (which may not be null terminated).
Definition: StringRef.h:128
static const uint64_t PRIME64_1
Definition: xxhash.cpp:51
#define P(N)
static uint64_t mergeRound(uint64_t Acc, uint64_t Val)
Definition: xxhash.cpp:64
static const uint64_t PRIME64_5
Definition: xxhash.cpp:55
uint64_t read64le(const void *P)
Definition: Endian.h:370
uint32_t read32le(const void *P)
Definition: Endian.h:369
static const uint64_t PRIME64_3
Definition: xxhash.cpp:53
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:49