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