| //==- llvm/Support/RandomNumberGenerator.h - RNG for diversity ---*- C++ -*-==// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file defines an abstraction for deterministic random number |
| // generation (RNG). Note that the current implementation is not |
| // cryptographically secure as it uses the C++11 <random> facilities. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_SUPPORT_RANDOMNUMBERGENERATOR_H_ |
| #define LLVM_SUPPORT_RANDOMNUMBERGENERATOR_H_ |
| |
| #include "llvm/Support/Compiler.h" |
| #include "llvm/Support/DataTypes.h" // Needed for uint64_t on Windows. |
| #include <random> |
| #include <system_error> |
| |
| namespace llvm { |
| class StringRef; |
| |
| /// A random number generator. |
| /// |
| /// Instances of this class should not be shared across threads. The |
| /// seed should be set by passing the -rng-seed=<uint64> option. Use |
| /// Module::createRNG to create a new RNG instance for use with that |
| /// module. |
| class RandomNumberGenerator { |
| |
| // 64-bit Mersenne Twister by Matsumoto and Nishimura, 2000 |
| // http://en.cppreference.com/w/cpp/numeric/random/mersenne_twister_engine |
| // This RNG is deterministically portable across C++11 |
| // implementations. |
| using generator_type = std::mt19937_64; |
| |
| public: |
| using result_type = generator_type::result_type; |
| |
| /// Returns a random number in the range [0, Max). |
| result_type operator()(); |
| |
| static constexpr result_type min() { return generator_type::min(); } |
| static constexpr result_type max() { return generator_type::max(); } |
| |
| private: |
| /// Seeds and salts the underlying RNG engine. |
| /// |
| /// This constructor should not be used directly. Instead use |
| /// Module::createRNG to create a new RNG salted with the Module ID. |
| RandomNumberGenerator(StringRef Salt); |
| |
| generator_type Generator; |
| |
| // Noncopyable. |
| RandomNumberGenerator(const RandomNumberGenerator &other) = delete; |
| RandomNumberGenerator &operator=(const RandomNumberGenerator &other) = delete; |
| |
| friend class Module; |
| }; |
| |
| // Get random vector of specified size |
| std::error_code getRandomBytes(void *Buffer, size_t Size); |
| } |
| |
| #endif |