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//==- llvm/Support/RandomNumberGenerator.h - RNG for diversity ---*- C++ -*-==//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// 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
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