1 //==- llvm/Support/RandomNumberGenerator.h - RNG for diversity ---*- C++ -*-==// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file defines an abstraction for deterministic random number 11 // generation (RNG). Note that the current implementation is not 12 // cryptographically secure as it uses the C++11 <random> facilities. 13 // 14 //===----------------------------------------------------------------------===// 15 16 #ifndef LLVM_SUPPORT_RANDOMNUMBERGENERATOR_H_ 17 #define LLVM_SUPPORT_RANDOMNUMBERGENERATOR_H_ 18 19 #include "llvm/Support/Compiler.h" 20 #include "llvm/Support/DataTypes.h" // Needed for uint64_t on Windows. 21 #include <random> 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 public: 34 /// Returns a random number in the range [0, Max). 35 uint_fast64_t operator()(); 36 37 private: 38 /// Seeds and salts the underlying RNG engine. 39 /// 40 /// This constructor should not be used directly. Instead use 41 /// Module::createRNG to create a new RNG salted with the Module ID. 42 RandomNumberGenerator(StringRef Salt); 43 44 // 64-bit Mersenne Twister by Matsumoto and Nishimura, 2000 45 // http://en.cppreference.com/w/cpp/numeric/random/mersenne_twister_engine 46 // This RNG is deterministically portable across C++11 47 // implementations. 48 std::mt19937_64 Generator; 49 50 // Noncopyable. 51 RandomNumberGenerator(const RandomNumberGenerator &other) = delete; 52 RandomNumberGenerator &operator=(const RandomNumberGenerator &other) = delete; 53 54 friend class Module; 55 }; 56 } 57 58 #endif 59
