1 | //==- llvm/Support/RandomNumberGenerator.h - RNG for diversity ---*- C++ -*-==// |
2 | // |
3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
4 | // See https://llvm.org/LICENSE.txt for license information. |
5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
6 | // |
7 | //===----------------------------------------------------------------------===// |
8 | // |
9 | // This file defines an abstraction for deterministic random number |
10 | // generation (RNG). Note that the current implementation is not |
11 | // cryptographically secure as it uses the C++11 <random> facilities. |
12 | // |
13 | //===----------------------------------------------------------------------===// |
14 | |
15 | #ifndef LLVM_SUPPORT_RANDOMNUMBERGENERATOR_H_ |
16 | #define LLVM_SUPPORT_RANDOMNUMBERGENERATOR_H_ |
17 | |
18 | #include "llvm/Support/Compiler.h" |
19 | #include "llvm/Support/DataTypes.h" // Needed for uint64_t on Windows. |
20 | #include <random> |
21 | #include <system_error> |
22 | |
23 | namespace llvm { |
24 | class StringRef; |
25 | |
26 | /// A random number generator. |
27 | /// |
28 | /// Instances of this class should not be shared across threads. The |
29 | /// seed should be set by passing the -rng-seed=<uint64> option. Use |
30 | /// Module::createRNG to create a new RNG instance for use with that |
31 | /// module. |
32 | class RandomNumberGenerator { |
33 | |
34 | // 64-bit Mersenne Twister by Matsumoto and Nishimura, 2000 |
35 | // http://en.cppreference.com/w/cpp/numeric/random/mersenne_twister_engine |
36 | // This RNG is deterministically portable across C++11 |
37 | // implementations. |
38 | using generator_type = std::mt19937_64; |
39 | |
40 | public: |
41 | using result_type = generator_type::result_type; |
42 | |
43 | /// Returns a random number in the range [0, Max). |
44 | result_type operator()(); |
45 | |
46 | static constexpr result_type min() { return generator_type::min(); } |
47 | static constexpr result_type max() { return generator_type::max(); } |
48 | |
49 | private: |
50 | /// Seeds and salts the underlying RNG engine. |
51 | /// |
52 | /// This constructor should not be used directly. Instead use |
53 | /// Module::createRNG to create a new RNG salted with the Module ID. |
54 | RandomNumberGenerator(StringRef Salt); |
55 | |
56 | generator_type Generator; |
57 | |
58 | // Noncopyable. |
59 | RandomNumberGenerator(const RandomNumberGenerator &other) = delete; |
60 | RandomNumberGenerator &operator=(const RandomNumberGenerator &other) = delete; |
61 | |
62 | friend class Module; |
63 | }; |
64 | |
65 | // Get random vector of specified size |
66 | std::error_code getRandomBytes(void *Buffer, size_t Size); |
67 | } |
68 | |
69 | #endif |
70 | |